1625-0064 Stat/Authority

SUBCHAPTER S—SUBDIVISION AND STABILITY
170.185 Stability test preparations.
170.190 Stability test procedure modifications.
170.200 Estimated lightweight vertical center of gravity.

PART
170—STABILITY
REQUIREMENTS FOR ALL INSPECTED VESSELS
Subpart A—General Provisions

Subpart G—Special Installations

Sec.
170.001 Applicability.
170.003 Right of appeal.
170.005 Vessel alteration or repair.
170.010 Equivalents.
170.015 Incorporation by reference.
170.020 OMB control numbers assigned pursuant to the Paperwork Reduction Act.

170.235
170.245

Subpart H—Watertight Bulkhead Doors
170.248 Applicability.
170.250 Types and classes.
170.255 Class 1 doors; permissible locations.
170.260 Class 2 doors; permissible locations.
170.265 Class 3 doors; required locations.
170.270 Door design, operation, installation,
and testing.
170.275 Special requirements for cargo space
watertight doors.

Subpart B—Definitions
170.050
170.055

General terms.
Definitions concerning a vessel.

Subpart C—Plan Approval

Subpart I—Free Surface

170.070 Applicability.
170.075 Plans.
170.080 Stability booklet.
170.085 Information required before a stability test.
170.090 Calculations.
170.093 Specific approvals.
170.095 Data submittal for a vessel equipped
to lift.
170.100 Addresses for submittal of plans and
calculations.

170.285 Free surface correction for intact
stability calculations.
170.290 Free surface correction for damage
stability calculations.
170.295 Special considerations for free surface of passive roll stabilization tanks.
170.300 Special consideration for free surface of spoil in hopper dredge hoppers.
AUTHORITY: 43 U.S.C. 1333; 46 U.S.C. 2103,
3306, 3703; E.O. 12234, 45 FR 58801, 3 CFR, 1980
Comp., p. 277; Department of Homeland Security Delegation No. 0170.1.

Subpart D—Stability Instructions for
Operating Personnel

SOURCE: CGD 79–023, 48 FR 51010, Nov. 4,
1983, unless otherwise noted.

170.105 Applicability.
170.110 Stability booklet.
170.120 Stability letter.
170.125 Operating information for a vessel
engaged in lifting.
170.135 [Reserved]
170.140 Operating information for a vessel
constructed on or after January 1, 2009
and issued a SOLAS safety certificate.

Subpart A—General Provisions
§ 170.001 Applicability.
(a) This subchapter applies to each
vessel that is—
(1) Contracted for on or after March
11, 1996, except where specifically stated otherwise; and
(2) Either—
(i) Inspected under another subchapter of this chapter, or is a foreign
vessel that must comply with the requirements in subchapter O of this
chapter; or
(ii) Required by either subchapter C
or subchapter E of this chapter to meet
applicable requirements contained in
this subchapter.
(b) Each vessel contracted for before
March 11, 1996 may be constructed in

Subpart E—Intact Stability Criteria
170.160 Specific applicability.
170.165 International Code on Intact Stability.
170.170 Weather criteria.
170.173 Criterion for vessels of unusual proportion and form.

pmangrum on DSK3VPTVN1PROD with CFR

Subpart F—Determination of Lightweight
Displacement and Centers of Gravity
170.174
170.175
170.180
the

Fixed ballast.
Form flotation material.

Specific applicability.
Stability test: General.
Plans and information required at
stability test.

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Coast Guard, DHS

§ 170.015

accordance with the regulations in effect at the time. However, any alterations or repairs must be done in accordance with § 170.005.
(c) Certain regulations in this subchapter apply only to limited categories of vessels. Specific applicability statements are provided at the
beginning of those regulations.

CFR part 51. To enforce any edition
other than that specified in this section, the Coast Guard must publish a
notice of change in the FEDERAL REGISTER and the material must be available to the public. All approved material is available for inspection at the
National Archives and Records Administration (NARA). For information on
the availability of this material at
NARA, call 202–741–6030 or go to http://
www.archives.gov/federallregister/
codeloflfederallregulations/
ibrllocations.html. It is also available
for inspection at the Coast Guard, Office of Design and Engineering Standards (CG–521), 2100 2nd St., SW., Stop
7126, Washington, DC 20593–7126, and is
available from the sources listed below.
(b) American Society for Testing and
Materials (ASTM), 100 Barr Harbor
Drive, West Conshohocken, PA 19428–
2959.
(1) ASTM F 1196–00, Standard Specification for Sliding Watertight Door
Assemblies, 2008, incorporation by reference (IBR) approved for § 170.270.
(2) ASTM F 1197–00, Standard Specification for Sliding Watertight Door
Control Systems, 2007, IBR approved
for § 170.270.
(c) Naval Publications and Forms
Center, Code 1052, 5801 Tabor Avenue,
Philadelphia, PA 19120.
(1) MIL–P–21929B, Military Specification, Plastic Material, Cellular Polyurethane, Foam-in-Place, Rigid (2
Pounds per Cubic Foot), 15 January
1991, IBR approved for § 170.245.
(2) [Reserved]
(d) International Maritime Organization (IMO), Publications Section, 4 Albert Embankment, London SE1 7SR,
United Kingdom, +44 (0)20 7735 7611,
http://www.imo.org/.
(1) Resolution MSC.216(82), Adoption
of Amendments to the International
Convention for the Safety of Life At
Sea, 1974, As Amended (IMO Res.
MSC.216(82), Adopted on 8 December
2006, IBR approved for §§ 170.140 and
170.248.
(2) Resolution MSC 267(85), Adoption
of the International Code on Intact
Stability, 2008 (2008 IS Code), Adopted
on 4 December 2008, IBR approved for
§ 170.165.

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 89–037, 57 FR 41825, Sept. 11,
1992; CGD 85–080, 61 FR 943, Jan. 10, 1996;
USCG–2007–0030, 75 FR 78082, Dec. 14, 2010]

§ 170.003 Right of appeal.
Any person directly affected by a decision or action taken under this subchapter, by or on behalf of the Coast
Guard, may appeal therefrom in accordance with subpart 1.03 of this chapter.
[CGD 88–033, 54 FR 50382, Dec. 6, 1989]

§ 170.005 Vessel alteration or repair.
(a) Alterations and repairs to inspected vessels must be done—
(1) Under the direction of the Officer
in Charge, Marine Inspection; and
(2) Except as provided in paragraph
(b) of this section, in accordance with
the regulations in this subchapter, to
the extent practicable.
(b) Minor alterations and repairs may
be done in accordance with regulations
in effect at the time the vessel was
contracted for.
§ 170.010 Equivalents.
Substitutions for fittings, equipment,
arrangements, calculations, information, or tests required in this subchapter may be approved by the Commandant, the Commanding Officer,
U.S. Coast Guard Marine Safety Center, 2100 2nd St., SW., Stop 7102, Washington, DC 20593–7102, or the Officer in
Charge, Marine Inspection, if the substitution provides an equivalent level
of safety.

pmangrum on DSK3VPTVN1PROD with CFR

[USCG–2007–29018, 72 FR 53968, Sept. 21, 2007,
as amended by USCG–2009–0702, 74 FR 49239,
Sept. 25, 2009]

§ 170.015 Incorporation by reference.
(a) Certain material is incorporated
by reference into this part with the approval of the Director of the Federal
Register under 5 U.S.C. 552(a) and 1

[USCG–2007–0030, 75 FR 78082, Dec. 14, 2010]

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§ 170.020

46 CFR Ch. I (10–1–11 Edition)
Rosiers to West Point, Anticosti Island, and west of a line along the 63rd
meridian from Anticosti Island to the
north shore of the St. Lawrence River.
(e) Lakes, Bays, and Sounds includes
the waters of any lake, bay, or sound,
except the Great Lakes.
(f) Oceans includes the waters of—
(1) Any ocean;
(2) The Gulf of Mexico;
(3) The Caribbean Sea;
(4) The Gulf of Alaska; and
(5) Any other waters designated as
‘‘oceans’’ by the Commandant.
(g) Officer in Charge Marine Inspection
(OCMI) means an officer of the Coast
Guard who commands a Marine Inspection Zone described in 33 CFR part 3 or
an authorized representative of that officer.
(h) Oil means oil of any kind or in
any form, and includes but is not limited to petroleum, fuel oil, sludge, oil
refuse, and oil mixed with wastes other
than dredged spoil.
(i) Partially protected waters means—
(1) Waters within 20 nautical miles
(37 kilometers) of the mouth of a harbor of safe refuge, unless determined by
the OCMI to be exposed waters; and
(2) Those portions of rivers, harbors,
lakes, etc. which the OCMI determines
not to be sheltered.
(j) Protected waters means sheltered
waters presenting no special hazards
such as most rivers, harbors, lakes, etc.
(k) Rivers means any river, canal, or
any other similar body of water designated by the OCMI.

§ 170.020 OMB control numbers assigned pursuant to the Paperwork
Reduction Act.
(a) Purpose. This section collects and
displays the control numbers assigned
to information collection and recordkeeping requirements in this subchapter by the Office of Management
and Budget (OMB) pursuant to the Paperwork Reduction Act of 1980 (44
U.S.C. 3501 et seq.). The Coast Guard intends that this section comply with the
requirements of 44 U.S.C. 3507(f), which
requires that agencies display a current control number assigned by the
OMB for each approved agency information collection requirement.
(b) Display.
46 CFR part—
§ 170.075
§ 170.080
§ 170.085
§ 170.090
§ 170.095
§ 170.100
§ 170.110
§ 170.120
§ 170.125
§ 170.135
§ 170.180

Current OMB control No.

...................................
...................................
...................................
...................................
...................................
...................................
...................................
...................................
...................................
...................................
...................................

1625–0064
1625–0064
1625–0064
1625–0064
1625–0064
1625–0064
1625–0064
1625–0064
1625–0064
1625–0064
1625–0064

[CGD 89–037, 57 FR 41825, Sept. 11, 1992, as
amended by USCG–2004–18884, 69 FR 58350,
Sept. 30, 2004]

pmangrum on DSK3VPTVN1PROD with CFR

Subpart B—Definitions
§ 170.050 General terms.
(a) Commanding Officer, Marine Safety
Center (CO, MSC) means a district commander described in 33 CFR part 3
whose command includes a merchant
marine technical office or an authorized representative of the district commander.
(b) Commandant means the Commandant of the Coast Guard or an authorized representative of the Commandant.
(c) Exposed waters means waters more
than 20 nautical miles (37 kilometers)
from the mouth of a harbor of safe refuge and other waters which the Officer
in Charge, Marine Inspection determines to present special hazards due to
weather or other circumstances.
(d) Great Lakes includes both the
waters of the Great Lakes and of the
St. Lawrence River as far east as a
straight line drawn from Cap de

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988]

§ 170.055 Definitions concerning a vessel.
(a) Assumed average weight per person
means the weight calculated in accordance with § 170.090 of this part.
(b) Auxiliary sailing vessel means a
vessel capable of being propelled both
by mechanical means and by sails.
(c) Barge means a vessel not equipped
with a means of self-propulsion.
(d) Beam or B means the maximum
width of a vessel from—
(1) Outside of planking to outside of
planking on wooden vessels; and
(2) Outside of frame to outside of
frame on all other vessels.

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Coast Guard, DHS

§ 170.055

(e) Bulkhead deck means the uppermost deck to which watertight bulkheads and the watertight shell extend.
(f) Constructed means the date—
(1) The vessel’s keel was laid; or
(2) Construction identifiable with the
vessel began and assembly of that vessel commenced comprising of 50 metric
tons or at least 1 percent of the estimated mass of all structural material,
whichever is less.
(g) Downflooding means, except as
provided in § 174.035(b), the entry of seawater through any opening into the
hull or superstructure of an undamaged
vessel due to heel, trim, or submergence of the vessel.
(h) Documented alterations means
changes to the vessel which are reflected in the approved stability information carried on board the vessel.
(i) Downflooding angle means, except
as specified by §§ 171.055(f), 172.090(d),
173.095(e), 174.015(b), and 174.035(b)(2) of
this chapter, the static angle from the
intersection of the vessel’s centerline
and waterline in calm water to the
first opening that cannot be closed watertight
and
through
which
downflooding can occur.
(j) Draft means the vertical distance
from the molded baseline amidships to
the waterline.
(k) Length means the distance between fore and aft points on a vessel.
The following specific terms are used
and correspond to specific fore and aft
points:
(1) Length between perpendiculars
(LBP) means the horizontal distance
measured
between
perpendiculars
taken at the forward-most and aftermost points on the waterline corresponding to the deepest operating
draft. For a small passenger vessel that
has underwater projections extending
forward of the forward-most point or
aft of the after-most point on the deepest waterline of the vessel, the Commanding Officer, U.S. Coast Guard Marine Safety Center, may include the
length or a portion of the length of the
underwater projections in the value
used for the LBP for the purposes of
this subchapter. The length or a portion of the length of projections that
contribute more than 2 percent of the
underwater volume of the vessel is normally added to the actual LBP.

(2) Length overall (LOA) means the
horizontal distance between the forward-most and after-most points on
the hull.
(3) Length on the waterline (LWL)
means the horizontal distance between
the forward-most and after-most points
on a vessel’s waterline.
(4) Length on deck (LOD) means the
length between the forward-most and
after-most points on a specified deck
measured along the deck, excluding
sheer.
(5) Load line length (LLL) has the
same meaning that is provided for the
term length in § 42.13–15(a) of this chapter.
(6) Mean length is the average of the
length between perpendiculars (LBP)
and the length on deck (LOD).
(l) Lightweight means the displacement of a vessel with fixed ballast and
with machinery liquids at operating
levels but without any cargo, stores,
consumable liquids, water ballast, or
persons and their effects.
(m) Main transverse watertight bulkhead means a transverse bulkhead that
must be maintained watertight in
order for the vessel to meet the damage
stability and subdivision requirements
in this subchapter.
(n) Major conversion, as applied to
Great Lakes bulk carriers, means a
conversion of an existing vessel that
substantially changes the dimensions
or carrying capacity of the vessel or
changes the type of vessel or substantially prolongs its life or that otherwise so changes the vessel that it is essentially a new vessel.
(o) Permeability is the percentage of
the volume of a space that can be occupied by water.
(p) Sailing vessel means a vessel propelled only by sails.
(q) Ship means a self-propelled vessel.
(r) Tank vessel means a vessel that is
specially constructed or converted to
carry liquid bulk cargo in tanks.
(s) Tank barge means a tank vessel
not equipped with a means of self-propulsion.
(t) Tank ship means a tank vessel
propelled by mechanical means or
sails.
(u) Vessel means any vessel and includes both ships and barges.

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§ 170.070

46 CFR Ch. I (10–1–11 Edition)

(v) Weather deck means the uppermost deck exposed to the weather.
(w) Existing sailing school vessel means
a sailing vessel whose keel was laid
prior to (January 9, 1986), which has an
application for initial inspection for
certification as a sailing school vessel
on file with the Coast Guard prior to
(January 9, 1987), and whose initial inspection for certification is completed
prior to (January 9, 1988).
(x) New sailing school vessel means a
sailing school vessel which is not an
existing sailing school vessel.
(y) Small passenger vessel means a vessel of less than 100 gross tons—
(1) Carrying more than 6 passengers,
including at least one passenger for
hire;
(2) That is chartered with the crew
provided or specified by the owner or
owner’s representative and carrying
more than 6 passengers;
(3) That is chartered with no crew
provided or specified by the owner or
owner’s representative and carrying
more than 12 passengers; or
(4) That is a submersible vessel carrying at least one passenger for hire.

(3) A tank vessel that only carries a
product listed in § 30.25–1 of this chapter and that is less than 150 gross tons.
(4) A tank barge that—
(i) Operates only in rivers or lakes,
bays, and sounds service;
(ii) Does not have to meet 33 CFR
part 157, subpart B; and
(iii) Only carries a product listed in
§ 30.25–1 of this chapter.
(5) A sailing school vessel that is an
open boat that complies with the requirements in § 173.063(e) of this subchapter.
[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 83–005, 51 FR 923, Jan. 9,
1986; USCG–2007–0030, 75 FR 78083, Dec. 14,
2010]

§ 170.075

[CGD 79–023, 48 FR 51010, Nov. 4, 1983]
EDITORIAL NOTE: For FEDERAL REGISTER citations affecting § 170.055, see the List of CFR
Sections Affected, which appears in the
Finding Aids section of the printed volume
and at www.fdsys.gov.

Subpart C—Plan Approval

pmangrum on DSK3VPTVN1PROD with CFR

§ 170.070

Plans.

(a) Except as provided in paragraph
(b) of this section, each applicant for
an original certificate of inspection
and approval of plans must also submit
three copies for plan review being conducted by the Coast Guard Marine
Safety Center of each of the following
plans:
(1) General arrangement plan of
decks, holds, and inner bottoms including inboard and outboard profiles.
(2) Lines.
(3) Curves of form.
(4) Capacity plan showing capacities
and vertical, longitudinal, and transverse centers of gravity of stowage
spaces and tanks.
(5) Tank sounding tables showing—
(i) Capacities, vertical centers of
gravity, and longitudinal centers of
gravity in graduated intervals; and
(ii) Free surface data for each tank.
(6) Draft mark locations including
longitudinal location and vertical reference points.
(b) Each small passenger vessel that
is designed to comply with the alternate intact stability requirements in
§ 178.320 of this subchapter and the simplified method of spacing main transverse watertight bulkheads in § 179.220
of this subchapter does not have to
submit the plans required by paragraph
(a) of this section.

Applicability.

(a) Except as provided in paragraph
(b) of this section, this subpart applies
to each vessel.
(b) This subpart does not apply to
any of the following vessels unless the
stability of the vessel is questioned by
the OCMI, or regulations by which the
vessel is inspected require their application:
(1) A passenger vessel that—
(i) Is less than 100 gross tons;
(ii) Is less than 65 feet (19.8 meters)
LOD measured over the weather deck;
and
(iii) Carries 49 or less passengers.
(2) A deck cargo barge that complies
with the requirements in § 174.020 of
this chapter.

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 944, Jan. 10,
1996; CGD 95–028, 62 FR 51217, Sept. 30, 1997;
USCG–2007–0030, 75 FR 78083, Dec. 14, 2010]

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Coast Guard, DHS

§ 170.090
this section. As of the effective date of
the first AAWPP update after December 1, 2011, this paragraph (d)(1) will be
superseded and cease to be effective.
(2) The formula in paragraph (e) of
this section will be used to determine
an update to the AAWPP. It requires
the use of data in the most recent report released by the Centers for Disease Control and Prevention (CDC)
through the National Center for Health
Statistics (NCHS), or any successors to
those centers. This report can be found
on the CDC’s Web site.
(3) Each time the CDC releases a report containing mean weights of
United States adult males and females,
the Coast Guard will apply the formula
in paragraph (e) of this section to that
data. The resulting value will become
the new AAWPP only if the sum equals
or exceeds 10 pounds more than the
AAWPP then in effect. The Coast
Guard will notify the public of the new
AAWPP in the FEDERAL REGISTER and
other appropriate media.
(4) Updates to the AAWPP used in
calculations showing compliance with
this subchapter will be promulgated as
interpretive rules and become effective
in accordance with the provisions of
this section without further rulemaking procedures.
(5) Notwithstanding any other provisions of this section, the Coast Guard
may choose, in its discretion, to conduct further rulemaking procedures at
any time to amend this subchapter, including updates of the AAWPP.
(6) Updates to the AAWPP used in
calculations showing compliance with
this subchapter will be published in a
separate FEDERAL REGISTER notice and
other appropriate media, except when
the Coast Guard conducts further rulemaking procedures under paragraph
(d)(5) of this section.
(7) Notwithstanding any other provisions of this section, the Coast Guard
may choose, in its discretion, to delay
or dispense with any update of the
AAWPP. In the event the Coast Guard
elects to dispense with or delay an update that would otherwise issue as an
interpretive rule pursuant to the provisions of this section, the Coast Guard
will inform the public of the decision
and explain the reasons in a FEDERAL
REGISTER notice.

§ 170.080 Stability booklet.
Before issuing an original certificate
of inspection, the following number of
copies of the stability booklet required
by § 170.110 must be submitted for approval; three copies for plan review
being conducted by the Coast Guard
Marine Safety Center.
[CGD 95–028, 62 FR 51217, Sept. 30, 1997, as
amended by USCG–2007–0030, 75 FR 78083,
Dec. 14, 2010]

§ 170.085 Information required before
a stability test.
If a stability test is to be performed,
a stability test procedure that contains
the
information
prescribed
in
§ 170.185(g) must be submitted to the
Coast Guard Marine Safety Center at
least two weeks before the test.

pmangrum on DSK3VPTVN1PROD with CFR

[CGD 95–028, 62 FR 51217, Sept. 30, 1997, as
amended by USCG–2007–0030, 75 FR 78083,
Dec. 14, 2010]

§ 170.090 Calculations.
(a) All calculations required by this
subchapter must be submitted with the
plans required by § 170.075 of this subpart. Calculations must account for the
weight of all loads carried aboard the
vessel.
(b) If it is necessary to compute and
plot any of the following curves as part
of the calculations required in this subchapter, these plots must also be submitted:
(1) Righting arm or moment curves.
(2) Heeling arm or moment curves.
(3) Cross curves of stability.
(4) Floodable length curves.
(c) The assumed weight per person
for calculations showing compliance
with the regulations of this subchapter
must be representative of the passengers and crew aboard the vessel
while engaged in the service intended.
Unless the Officer in Charge, Marine
Inspection (OCMI) permits or requires
the use of other values in writing, the
assumed weight per person of passengers and crew must not be less than
that the Assumed Average Weight per
Person (AAWPP) calculated in accordance with paragraphs (d) and (e) of this
section.
(d)(1) The AAWPP is 185 lb from December 1, 2011 until the AAWPP is first
updated pursuant to the provisions of

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§ 170.093

46 CFR Ch. I (10–1–11 Edition)

(e) To obtain an AAWPP update, add
the mean weight of all U.S. males aged
20 years and older to the mean weight
of all U.S. females aged 20 years and
older, and divide the sum by 2. To this
average of the mean weights, add 7.5
pounds of assumed clothing weight,
and round the resulting sum to the
nearest whole number in pounds.
(f) Updates to the AAWPP will become effective beginning one calendar
year after publication in the FEDERAL
REGISTER of a notice described in paragraphs (d)(3) and (d)(6) of this section,
except the initial AAWPP issued pursuant to paragraph (d)(1) of this section
will become effective on December 1,
2011. Notwithstanding any other provisions of this title, the Coast Guard may
implement updates to the AAWPP at
any time with less than one year of
public notice when required for public
safety reasons.
(g) The most recent FEDERAL REGISTER notice that publishes the AAWPP
as determined by this section is also on
file at the U.S. Coast Guard, Office of
Design and Engineering Standards
(CG–521), 2100 2nd St., SW., Stop 7126,
Washington DC 20593–7126, or go to:
http://www.uscg.mil/hq/cg5/cg5212

deck to which the hook load can be
raised.
(c) A table showing maximum
vertical and transverse moments at
which the crane is to operate.
§ 170.100 Addresses for submittal of
plans and calculations.
The plans, information, and calculations required by this subpart must be
submitted to one of the following:
(a) The Sector Office in the zone
where the vessel is to be built or altered.
(b) By visitors to the Commanding
Officer, U.S. Coast Guard Marine Safety Center, 1900 Half Street, SW., Suite
1000, Room 525, Washington, DC 20024,
or by mail to: Commanding Officer,
U.S. Coast Guard Marine Safety Center, 2100 2nd St., SW., Stop 7102, Washington, DC 20593–7102, in a written or
electronic format. Information for submitting the VSP electronically can be
found at http://www.uscg.mil/HQ/MSC.
[CGD 95–028, 62 FR 51217, Sept. 30, 1997, as
amended by USCG–2006–25556, 72 FR 36330,
July 2, 2007; USCG–2007–29018, 72 FR 53968,
Sept. 21, 2007; USCG–2009–0702, 74 FR 49239,
Sept. 25, 2009; USCG–2007–0030, 75 FR 78083,
Dec. 14, 2010]

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by USCG–2007–0030, 75 FR 78083,
Dec. 14, 2010; 76 FR 16698, Mar. 25, 2011]

§ 170.093

Subpart D—Stability Instructions for
Operating Personnel

Specific approvals.

§ 170.105

Certain rules in this subchapter require specific approval of equipment or
arrangements by the Commandant,
OCMI, or Coast Guard Marine Safety
Center. These approval determinations
will be made as a part of the plan review process.
[CGD 95–028, 62 FR 51217, Sept. 30, 1997, as
amended by USCG–2007–0030, 75 FR 78083,
Dec. 14, 2010]

§ 170.095 Data submittal for a vessel
equipped to lift.

pmangrum on DSK3VPTVN1PROD with CFR

Applicability.

(a) Except as provided in paragraph
(b) of this section, this subpart applies
to each vessel.
(b) This subpart does not apply to
any of the following vessels unless the
stability of the vessel is questioned by
the OCMI:
(1) A deck cargo barge that complies
with the requirements in § 174.020 of
this chapter.
(2) A tank vessel that only carries a
product listed in § 30.25–1 of this chapter and that is less than 150 gross tons.
(3) A tank barge that—
(i) Operates only in rivers or lakes,
bays, and sounds service;
(ii) Does not have to meet 33 CFR
part 157, subpart B; and
(iii) Only carries a product listed in
§ 30.25–1 of this chapter.

The following data must be submitted with the plans required by
§ 170.075 if the vessel is engaged in lifting and is required to comply with subpart B of part 173 of this chapter:
(a) A graph of maximum hook load
versus maximum crane radius.
(b) A table of crane radius versus the
maximum distance above the main

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Coast Guard, DHS

§ 170.110

(4) A sailing school vessel that is an
open boat that complies with the requirements in § 173.063(e) of this subchapter.
(5) A small passenger vessel inspected
under subchapter T of this chapter if
§ 178.210(c) of this chapter is applicable.

(6) Tank sounding tables showing capacities, vertical centers of gravity,
and longitudinal centers of gravity in
graduated intervals and showing free
surface data for each tank.
(7) Information on loading restrictions, such as a maximum KG or minimum GM curve that can be used to determine compliance with applicable intact and damage stability criteria.
(8) Examples of loading conditions.
(9) A rapid and simple means for evaluating other loading conditions.
(10) A brief description of the stability calculations done including assumptions.
(11) General precautions for preventing unintentional flooding.
(12) A table of contents and index for
the booklet.
(13) Each ship condition which, if
damage occurs, may require crossflooding for survival and information
concerning the use of any special crossflooding fittings.
(14) The amount and location of fixed
ballast.
(15) Any other necessary guidance for
the safe operation of the vessel under
normal and emergency conditions.
(16) For each self-propelled hopper
dredge with a working freeboard, the
maximum specific gravity allowed for
dredge spoil.
(e) A stability booklet is not required
if sufficient information to enable the
master to operate the vessel in compliance with the applicable regulations in
this subchapter can be placed on the
Certificate of Inspection, Load Line
Certificate, or in the stability letter
required in § 170.120.
(f) On board electronic stability computers may be used as an adjunct to
the required booklet, but the required
booklet must contain all necessary information to allow for the evaluation
of the stability of any intact condition
that can be evaluated by use of the
computer.

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 83–005, 51 FR 923, Jan. 9,
1986; CGD 85–080, 61 FR 944, Jan. 10, 1996;
USCG–2007–0030, 75 FR 78084, Dec. 14, 2010]

pmangrum on DSK3VPTVN1PROD with CFR

§ 170.110

Stability booklet.

(a) Except as provided in paragraph
(e) of this section, a stability booklet
must be prepared for each vessel, except for mobile offshore drilling units
subject to the operating manual requirements of § 109.121 of this chapter.
(b) Each stability booklet must be
approved by the Coast Guard Marine
Safety Center.
(c) Each stability book must contain
sufficient information to enable the
master to operate the vessel in compliance with applicable regulations in this
subchapter. Information on loading restrictions used to determine compliance with applicable intact and damage stability criteria must encompass
the entire range of operating drafts and
the entire range of the operating trims.
Information must include an effective
procedure for supervision and reporting
of the opening and closing of all loading doors, where applicable.
(d) The format of the stability booklet and the information included will
vary dependent on the vessel type and
operation. Units of measure used in the
stability booklet must agree with the
units of measure of the draft markings.
In developing the stability booklet,
consideration must be given to including the following information:
(1) A general description of the vessel, including lightweight data.
(2) Instructions on the use of the
booklet.
(3) General arrangement plans showing watertight compartments, closures,
vents, downflooding angles, and allowable deck loadings.
(4) Hydrostatic curves or tables.
(5) Capacity plan showing capacities
and vertical, longitudinal, and transverse centers of gravity of stowage
spaces and tanks.

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 83–071, 52 FR 6979, Mar. 6,
1987; CGD 88–070, 53 FR 34537, Sept. 7, 1988;
CGD 76–080, 54 FR 36977, Sept. 6, 1989; CGD 89–
037, 57 FR 41825, Sept. 11, 1992; CGD 95–028, 62
FR 51217, Sept. 30, 1997; USCG–2007–0030, 75
FR 78084, Dec. 14, 2010]

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§ 170.120

46 CFR Ch. I (10–1–11 Edition)
(2) Issued either a SOLAS Passenger
Ship Safety Certificate or a SOLAS
Cargo Ship Safety Construction Certificate.
(b) In addition to the information required in § 170.110 of this part, the stability booklet of each vessel to which
this section applies must contain the
information required by applicable regulations of IMO Res. MSC.216(82) (incorporated by reference, see § 170.015).
(c) As used in SOLAS chapter II–1,
Administration means the Commandant,
U.S. Coast Guard.

§ 170.120 Stability letter.
(a) Except as provided in paragraph
(b) of this section, each vessel must
have a stability letter issued by the
Coast Guard before the vessel is placed
into service. This letter sets forth conditions of operation.
(b) A stability letter is not required
if the information can be placed on the
Certificate of Inspection or the Load
Line Certificate.
[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 95–028, 62 FR 51217, Sept. 30,
1997; USCG–2007–0030, 75 FR 78084, Dec. 14,
2010]

[USCG–2007–0030, 75 FR 78084, Dec. 14, 2010]

Subpart E—Intact Stability Criteria

§ 170.125 Operating information for a
vessel engaged in lifting.
In addition to the information required in § 170.110, the following information must be included in the stability booklet of a vessel that is required to comply with § 173.005 of this
subchapter:
(a) Non-counterballasted vessel. If a
vessel is not counterballasted, stability
information setting forth hook load
limits corresponding to boom radii
based on the intact stability criterion
in § 173.020 must be provided.
(b) Counterballasted vessel. If a vessel
is counterballasted with water, the following information must be provided:
(1) Instructions on the effect of the
free surface of the counterballast
water.
(2) Instructions on the amounts of
counterballast needed to compensate
for hook load heeling moments.
(3) If a vessel has fixed counterballast, a table of draft versus maximum
vertical moment of deck cargo and
hook load combined.
(4) If a vessel has variable counterballast, a table of draft versus maximum vertical moment of deck cargo
and hook load combined for each
counterballasted condition.

pmangrum on DSK3VPTVN1PROD with CFR

§ 170.135

§ 170.160 Specific applicability.
(a) Except as provided in paragraphs
(b) through (d) of this section, this subpart applies to each vessel.
(b) This subpart does not apply to
any of the following vessels unless the
stability of the vessel is questioned by
the OCMI:
(1) A deck cargo barge that complies
with the requirements in § 174.020 of
this chapter.
(2) A tank vessel that only carries a
product listed in § 30.25–1 of this chapter and that is—
(i) Less than 150 gross tons; or
(ii) A tank barge that operates only
in river or lakes, bays, and sounds service.
(3) A sailing school vessel that is an
open boat that complies with the requirements in § 173.063(e) of this subchapter.
(c) This subpart does not apply to the
following vessels:
(1) A tank barge that carries a product listed in Table 151.05 of this chapter.
(2) A mobile offshore drilling unit.
(3) A vessel that performs one of the
simplified stability proof tests described in subpart C of part 178 of this
chapter.
(d) A vessel that complies with
§ 170.165 of this part need not comply
with §§ 170.170 and 170.173 of this part.

[Reserved]

§ 170.140 Operating information for a
vessel constructed on or after January 1, 2009 and issued a SOLAS
safety certificate.
(a) This section applies to each vessel
that is—
(1) Constructed on or after January 1,
2009; and

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 83–005, 51 FR 923, Jan. 9,
1986; CGD 85–080, 61 FR 944, Jan. 10, 1996;
USCG–2007–29018, 72 FR 53968, Sept. 21, 2007;
USCG–2009–0702, 74 FR 49239, Sept. 25, 2009;
USCG–2007–0030, 75 FR 78084, Dec. 14, 2010]

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Coast Guard, DHS

§ 170.173
water lateral area or approximately to the
one-half draft point.
W=displacement in long (metric) tons.
T=either:
(1) the lesser of either 14 degrees heel or
the angle of heel in degrees at which onehalf the freeboard to the deck edge is immersed; or
(2) for a sailing vessel, T = the lesser of either 14 degrees or the angle of heel in degrees to the deck edge.
The deck edge is to be taken as the intersection of the sideshell and the uppermost
continuous deck below which the sideshell is
weathertight.

§ 170.165 International Code on Intact
Stability.
(a) Each vessel issued one or more of
the certificates listed in paragraphs
(a)(1) through (4) of this section, must
comply with the Introduction and Part
A of the International Code on Intact
Stability, 2008 (2008 IS Code), unless
permitted otherwise (incorporated by
reference, see § 170.015).
(1) International Load Line Certificate.
(2) SOLAS Passenger Ship Safety
Certificate.
(3) SOLAS Cargo Ship Safety Construction Certificate.
(4) High-speed Craft Safety Certificate.
(b) A vessel not subject to the requirements of paragraph (a) of this section is permitted to comply with the
applicable criteria contained in the
2008 IS Code as an alternative to the requirements of §§ 170.170 and 170.173 of
this part.

(b) If approved by the Coast Guard
Marine Safety Center or the ABS, a
larger value of T may be used for a vessel with a discontinuous weather deck
or abnormal sheer.
(c) When doing the calculations required by paragraph (a) of this section
for a sailing vessel or auxiliary sailing
vessel, the vessel must be assumed—
(1) To be under bare poles; or
(2) If the vessel has no auxiliary propulsion, to have storm sails set and
trimmed flat.
(d) The criterion specified in this section is generally limited in application
to the conditions of loading and operation of flush deck, mechanically powered vessels of ordinary proportions
and form for which the righting arm
(GZ) at the angle (T), calculated after
the vessel is permitted to trim free
until the trimming moment is zero, is
not
less
than
the
minimum
metacentric height (GM) calculated in
paragraph (a) of this section multiplied
by sin(T). On other types of vessels, the
Coast Guard Marine Safety Center requires calculations in addition to those
in paragraph (a) of this section. On a
mechanically powered vessel under 328
feet (100 meters) in length, other than
a tugboat or a towboat, the requirements in § 170.173 are applied.

[USCG–2007–0030, 75 FR 78084, Dec. 14, 2010]

§ 170.170

Weather criteria.

(a) Each vessel must be shown by design calculations to have a metacentric
height (GM) that is equal to or greater
than the following in each condition of
loading and operation:

PAH
W tan (T)

Where—
P=.005+(L/14,200)2 tons/ft2 . . . for ocean service, Great Lakes winter service, or service
on exposed waters.
metric
tons/m2 . . . for
P=.055+(L/1309)2
ocean service, Great Lakes winter service,
or service on exposed waters.
P=.0033+(L/14,200)2 tons/ft2 . . . for Great
Lakes summer service or service on partially protected waters.
P=.036+(L/1309)2 metric tons/m2 . . . for Great
lakes summer service or service on partially protected waters.
P=.0025+(L/14,200)2 tons/ft2 . . . for service on
protected waters.
P=.028+(L/1309)2 metric tons/m2 . . . for service on protected waters.
L=LBP in feet (meters).
A=projected lateral area in square feet
(square meters) of the portion of the vessel
and deck cargo above the waterline.
H=the vertical distance in feet (meters) from
the center of A to the center of the under-

[CGD 79–023, 48 FR 51010, Nov. 4, 1983; 49 FR
37384, Sept. 24, 1984, as amended by CGD 88–
070, 53 FR 34537, Sept. 7, 1988; CGD 85–080, 61
FR 944, Jan. 10, 1996; 61 FR 20556, May 7, 1996;
CGD 95–028, 62 FR 51217, Sept. 30, 1997; USCG–
2007–0030, 75 FR 78084, Dec. 14, 2010]

§ 170.173 Criterion for vessels of unusual proportion and form.
(a) If required by the Coast Guard
Marine Safety Center, each mechanically powered vessel less than 328 feet
(100 meters) LLL, other than a tugboat

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EC13NO91.043

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GM ≥

pmangrum on DSK3VPTVN1PROD with CFR

§ 170.174

46 CFR Ch. I (10–1–11 Edition)

or towboat, must be shown by design
calculations to comply with—
(1) Paragraph (b) or (c) of this section
if the maximum righting arm occurs at
an angle of heel less than or equal to 30
degrees; or
(2) Paragraph (b) of this section if the
maximum righting arm occurs at an
angle of heel greater than 30 degrees.
(b) Each vessel must have—
(1) An initial metacentric height
(GM) of at least 0.49 feet (0.15 meters);
(2) A righting arm (GZ) of at least
0.66 feet (0.20 meters) at an angle of
heel equal to or greater than 30 degrees;
(3) A maximum righting arm that occurs at an angle of heel not less than 25
degrees;
(4) An area under each righting arm
curve of at least 10.3 foot-degrees (3.15
meter-degrees) up to an angle of heel of
30 degrees;
(5) An area under each righting arm
curve of at least 16.9 foot-degrees (5.15
meter-degrees) up to an angle of heel of
40 degrees or the downflooding angle,
whichever is less; and
(6) An area under each righting arm
curve between the angles of 30 degrees
and 40 degrees, or between 30 degrees
and the downflooding angle if this
angle is less than 40 degrees, of not less
than 5.6 foot-degrees (1.72 meter-degrees).
(c) Each vessel must have—
(1) An initial metacentric height
(GM) of at least 0.49 feet (0.15 meters);
(2) A maximum righting arm that occurs at an angle of heel not less than 15
degrees;
(3) An area under each righting arm
curve of at least 16.9 foot-degrees (5.15
meter-degrees) up to an angle of heel of
40 degrees or the downflooding angle,
whichever is less;
(4) An area under each righting arm
curve between the angles of 30 degrees
and 40 degrees, or between 30 degrees
and the downflooding angle if this
angle is less than 40 degrees, of not less
than 5.6 foot-degrees (1.72 meter-degrees); and
(5) An area under each righting arm
curve up to the angle of maximum
righting arm of not less than the area
determined by the following equation:

A=3.15+0.057 (30¥Y) meter-degrees
where—
A=area in foot-degrees (meter-degrees).
Y=angle of maximum righting arm, degrees.

(d) For the purpose of demonstrating
compliance with paragraphs (b) and (c)
of this section, at each angle of heel a
vessel’s righting arm is calculated
after the vessel is permitted to trim
free until the trimming moment is
zero.
(e) For the purpose of demonstrating
acceptable stability on the vessels described in § 170.170(d) as having unusual
proportion and form, compliance with
paragraphs (a) through (d) of this section or the following criteria is required:
(1) For partially protected routes,
there must be—
(i) Positive righting arms to at least
35 degrees of heel;
(ii) No down flooding point to at least
20 degrees; and
(iii) At least 15 foot-degrees of energy
to the smallest of the following angles:
(A) Angle of maximum righting arm.
(B) Angle of down flooding.
(C) 40 degrees.
(2) For protected routes, there must
be—
(i) Positive righting arms to at least
25 degrees of heel;
(ii) No down flooding point to at least
15 degrees; and
(iii) At least 10 foot-degrees of energy
to the smallest of the following angles:
(A) Angle of maximum righting arm.
(B) Angle of down flooding.
(C) 40 degrees.
[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 944, Jan. 10,
1996; CGD 95–028, 62 FR 51218, Sept. 30, 1997; 62
FR 51353, Sept. 30, 1997; USCG–2007–0030, 75
FR 78084, Dec. 14, 2010]

Subpart F—Determination of Lightweight Displacement and
Centers of Gravity
§ 170.174

Specific applicability.

This subpart applies to each vessel
for which the lightweight displacement
and centers of gravity must be determined in order to do the calculations
required in this subchapter.

A=10.3+0.187 (30¥Y) foot-degrees

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Coast Guard, DHS
§ 170.175

§ 170.190

Stability test: General.

§ 170.185 Stability test preparations.
The following preparations must be
made before conducting a stability
test:
(a) The vessel must be as complete as
practicable at the time of the test.
(b) Each tank vessel must be empty
and dry, except that a tank may be
partially filled or full if the Coast
Guard Marine Safety Center determines that empty and dry tanks are
impracticable and that the effect of
filling or partial filling on the location
of the center of gravity and on the displacement can be accurately determined.
(c) All dunnage, tools, and other
items extraneous to the vessel must be
removed.
(d) The water depth at the mooring
site must provide ample clearance
against grounding.
(e) Each mooring line must be arranged so that it does not interfere
with the inclination of the unit during
the test.
(f) The draft and axis of rotation selected for testing a mobile offshore
drilling unit must be those that result
in acceptable accuracy in calculating
the center of gravity and displacement
of the unit.
(g) The stability test procedure required by § 170.085 must include the following:
(1) Identification of the vessel to be
tested.
(2) Date and location of the test.
(3) Inclining weight data.
(4) Pendulum locations and lengths.
(5) Approximate draft and trim of the
vessel.
(6) Condition of each tank.
(7) Estimated items to be installed,
removed, or relocated after the test, including the weight and location of each
item.
(8) Schedule of events.
(9) Person or persons responsible for
conducting the test.

(a) Except as provided in paragraphs
(c) and (d) of this section and in
§ 170.200, the owner of a vessel must
conduct a stability test of the vessel
and calculate its vertical and longitudinal centers of gravity and its lightweight displacement.
(b) An authorized Coast Guard representative must be present at each
stability test conducted under this section.
(c) The stability test may be dispensed with, or a deadweight survey
may be substituted for the stability
test, if the Coast Guard has a record of,
or is provided with, the approved results of a stability test of a sister vessel.
(d) The stability test of a vessel may
be dispensed with if the Coast Guard
determines that an accurate estimate
of the vessel’s lightweight characteristics can be made and that locating the
precise position of the vessel’s vertical
center of gravity is not necessary to
ensure that the vessel has adequate
stability in all probable loading conditions.
[CGD 79–023, 48 FR 51010, Nov. 4, 1983,
amended by CGD 95–028, 62 FR 51218, Sept.
1997; USCG–1998–4442, 63 FR 52192, Sept.
1998; USCG–2007–0030, 75 FR 78084, Dec.
2010]

§ 170.180 Plans and information
quired at the stability test.

as
30,
30,
14,

re-

pmangrum on DSK3VPTVN1PROD with CFR

The owner of a vessel must provide
the following Coast Guard approved
plans and information to the authorized Coast Guard representative at the
time of the stability test:
(a) Lines.
(b) Curves of form.
(c) Capacity plans showing capacities
and vertical and longitudinal centers of
gravity of stowage spaces and tanks.
(d) Tank sounding tables.
(e) Draft mark locations.
(f) General arrangement plan of
decks, holds, and inner bottoms.
(g) Inboard and outboard profiles.
(h) The stability test procedure described in § 170.185(g).

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988; CGD 95–028, 62 FR 51218, Sept. 30, 1997;
USCG–2007–0030, 75 FR 78084, Dec. 14, 2010]

§ 170.190 Stability
test
procedure
modifications.
The authorized Coast Guard representative present at a stability test

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 95–028, 62 FR 51218, Sept. 30,
1997; USCG–2007–0030, 75 FR 78084, Dec. 14,
2010]

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§ 170.200

46 CFR Ch. I (10–1–11 Edition)

may allow a deviation from the requirements of §§ 170.180 and 170.185 if
the representative determines that the
deviation would not decrease the accuracy of the test results.

tion or repair if done under the supervision of the OCMI.
[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988; CGD 95–028, 62 FR 51218, Sept. 30, 1997;
USCG–2007–0030, 75 FR 78084, Dec. 14, 2010]

[CGD 95–028, 62 FR 51218, Sept. 30, 1997, as
amended by USCG–2007–0030, 75 FR 78084,
Dec. 14, 2010]

§ 170.245

§ 170.200 Estimated
lightweight
vertical center of gravity.
(a) Each tank vessel that does not
carry a material listed in either Table
1 of part 153 or Table 4 of part 154 of
this chapter may comply with this section in lieu of § 170.175 if it—
(1) Is 150 gross tons or greater;
(2) Is of ordinary proportions and
form;
(3) Has a flush weather deck, one or
more longitudinal bulkheads, and no
independent tanks; and
(4) Is designed not to carry cargo
above the freeboard deck.
(b) When doing the calculations required by §§ 170.170 and 172.065, the
vertical center of gravity of a tank vessel in the lightweight condition must
be assumed to be equal to the following
percentage of the molded depth of the
vessel
measured
from
the
keel
amidship:
(1) For a tank ship—70%.
(2) For a tank barge—60%.
(c) As used in this section, molded
depth has the same meaning that is
provided for the term in § 42.13–15(e) of
this chapter.
[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 944, Jan. 10,
1996]

Subpart G—Special Installations

pmangrum on DSK3VPTVN1PROD with CFR

§ 170.235

Foam flotation material.

(a) Installation of foam must be approved by the OCMI.
(b) If foam is used to comply with
§ 171.070(d), § 171.095(c), or § 173.063(e) of
this subchapter, the following applies:
(1) Foam may be installed only in
void spaces that are free of ignition
sources.
(2) The foam must comply with NPFC
MIL–P–21929B (incorporated by reference; see 46 CFR 170.015), including
the requirements for fire resistance.
(3) A submergence test must be conducted for a period of at least 7 days to
demonstrate whether the foam has adequate strength to withstand a hydrostatic head equivalent to that which
would be imposed if the vessel were
submerged to its margin line.
(4) The effective buoyancy at the end
of the submergence test must be used
as the buoyancy credit; however, in no
case will a credit greater than 55 lbs
per cubic foot (881 kilograms per cubic
meter) be allowed.
(5) The structure enclosing the foam
must be strong enough to accommodate the buoyancy of the foam.
(6) Piping and cables must not pass
through foamed spaces unless they are
within piping and cable trunks accessible from both ends.
(7) Sample specimens must be prepared during installation and the density of the installed foam must be determined.
(8) Foam may be installed adjacent
to fuel tanks if the boundary between
the tank and space has double continuous fillet welds.
(9) MIL-P-21929B is incorporated by
reference into this part.
(10) The results of all tests and calculations must be submitted to the
OCMI.
(11) Blocked foam must—
(i) Be used in each area that may be
exposed to water; and

Fixed ballast.

(a) Fixed ballast, if used, must be—
(1) Installed under the supervision of
the OCMI; and
(2) Stowed in a manner that prevents
shifting of position.
(b) Fixed ballast may not be removed
from a vessel or relocated unless approved by the Coast Guard Marine
Safety Center. However, ballast may be
temporarily moved for vessel examina-

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Coast Guard, DHS

§ 170.260

(ii) Have a protective cover approved
by the OCMI.

a door of a class bearing a higher number may be used.

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 83–005, 51 FR 923, Jan. 9,
1986; USCG–2003–16630, 73 FR 65203, Oct. 31,
2008]

§ 170.255 Class 1 doors; permissible locations.
(a) Except as provided in paragraphs
(b) and (c) of this section, Class 1 doors
within passenger, crew, and working
spaces are permitted only above a
deck, the molded line of which, at its
lowest point at side, is at least 7 feet
(2.14 meters) above the deepest load
line.
(b) Class 1 doors are permitted within
passenger, crew, and working spaces,
wherever located, if—
(1) In the judgment of the OCMI, the
door is in a location where it will be
closed at all times except when actually in use; and
(2) The vessel is less than 150 gross
tons and will not proceed more than 20
nautical miles (37 kilometers) from
shore; or
(3) The vessel is in rivers or lakes,
bays, and sounds service.
(c) Class 1 doors are permitted in any
location on a vessel that—
(1) Is less than 100 gross tons; and
(2) Will operate only in the offshore
oil industry trade.
(d) Quick-acting Class 1 doors are
permitted in any location on a vessel
that operates on the Great Lakes and
is required to meet the damage stability standards of subpart H of part 172
of this chapter.
(e) For vessels required to meet the
damage stability standards of subpart
H of this chapter, when Class 1 doors
are installed below a deck the molded
line of which at its lowest point at side
is less than 7 feet (2.14 meters) above
the deepest load line, an indicator light
for each door which warns when the
door is open must be installed on the
bridge.

Subpart H—Watertight Bulkhead
Doors
§ 170.248

Applicability.

(a) Except as provided in paragraphs
(b) through (d) of this section, this subpart applies to vessels with watertight
doors in bulkheads that have been
made watertight to comply with the
flooding or damage stability regulations in this subchapter.
(b) A watertight door on a MODU
must comply with § 174.100 of this subchapter.
(c) A watertight door on a self-propelled hopper dredge with a working
freeboard must comply with § 174.335 of
this subchapter.
(d) Unless permitted otherwise, each
vessel constructed on or after January
1, 2009 and issued a SOLAS Passenger
Ship Safety Certificate or a SOLAS
Cargo Ship Safety Construction Certificate must comply with the applicable regulations of IMO Res. MSC.216(82)
in addition to the requirements of this
subpart (IMO Res. MSC.216(82) incorporated by reference, see § 170.015).
[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 76–080, 54 FR 36977, Sept. 6,
1989; USCG–2007–0030, 75 FR 78084, Dec. 14,
2010]

pmangrum on DSK3VPTVN1PROD with CFR

§ 170.250

Types and classes.

(a) Watertight doors, except doors between cargo spaces, are classed as follows:
(1) Class 1—Hinged door.
(2) Class 2—Sliding door, operated by
hand gear only.
(3) Class 3—Sliding door, operated by
power and by hand gear.
(b) The following types of watertight
doors are not permitted:
(1) A plate door secured only by
bolts; and
(2) A door required to be closed by
dropping or by the action of dropping
weights.
(c) Whenever a door of a particular
class is prescribed by these regulations,

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 80–159, 51 FR 33059, Sept. 18,
1986]

§ 170.260 Class 2 doors; permissible locations.
(a) Except as provided in paragraphs
(b) and (c) of this section, a Class 2
door is permitted only if—
(1) Its sill is above the deepest load
line; and

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46 CFR Ch. I (10–1–11 Edition)

(2) It is not a door described in
§ 170.265(d).
(b) If passenger spaces are located
below the bulkhead deck, Class 2 doors
with sills below the deepest load line
may be used if—
(1) The number of watertight doors
located below the deepest load line
that are used intermittently during operation of the vessel does not exceed
two, and;
(2) The doors provide access to or are
within spaces containing machinery.
(c) If no passenger spaces are located
below the bulkhead deck, Class 2 doors
may be used if the number of watertight doors located below the deepest
load line that are used intermittently
during operation of the vessel does not
exceed five.
(d) In determining whether Class 2
doors are allowed under paragraph (c)
of this section, the watertight doors at
the entrance to shaft tunnels need not
be counted. If Class 2 doors are allowed
under paragraph (c) of this section, the
doors at the entrance to shaft tunnels
may also be Class 2.

§ 170.270 Door design, operation, installation, and testing.
(a) Each Class 1 door must have a
quick action closing device operative
from both sides of the door.
(b) Each Class 1 door on a vessel in
ocean service must be designed to withstand a head of water equivalent to the
depth from the sill of the door to the
margin line but in no case less than 10
feet (3.05 meters).
(c) Each Class 2 and Class 3 door
must—
(1) Be designed, constructed, tested,
and marked in accordance with ASTM
F 1196 (incorporated by reference, see
§ 170.015);
(2) Have controls in accordance with
ASTM F 1197 (incorporated by reference, see § 170.015); and
(3) If installed in a subdivision bulkhead, meet Supplemental Requirements Nos. S1 and S3 of ASTM F 1196
(incorporated
by
reference,
see
§ 170.015), unless the watertight doors
are built in accordance with plans previously approved by the Coast Guard,
in which case, only Supplemental Requirements Nos. S1 and S3.1.4 of ASTM
F 1196 (incorporated by reference, see
§ 170.015) must be met. In either case,
control systems for watertight doors
must have power supplies, power
sources, installation tests and inspection, and additional remote operating
consoles in accordance with Supplemental Requirements Nos. S1 through
S4 of ASTM F 1197 (incorporated by reference, see § 170.015).
(d) Installations of sliding watertight
door assemblies must be in accordance
with the following:
(1) Before a sliding watertight door
assembly is installed in a vessel, the
bulkhead in the vicinity of the door
opening must be stiffened. Such bulkhead stiffeners, or deck reinforcement
where flush deck door openings are desired, must not be less than 6 inches
nor more than 12 inches from the door
frame so that an unstiffened diaphragm
of bulkhead plating 6 to 12 inches wide
is provided completely around the door
frame. Where such limits cannot be
maintained, alternative installations
will be considered by the Marine Safety
Center.
In
determining
the
scantlings of these bulkhead stiffeners,

pmangrum on DSK3VPTVN1PROD with CFR

§ 170.265 Class 3 doors; required locations.
The following doors must always be
Class 3:
(a) Doors in all locations not addressed in §§ 170.255 and 170.260.
(b) Doors between coal bunkers below
the bulkhead deck that must be opened
at sea.
(c) Doors into trunkways that pass
through more than one main transverse watertight bulkhead if the door
sills are less than 2.14 meters above the
deepest load line.
(d) Doors below a deck, the molded
line of which, at its lowest point at
side, is less than 2.14 meters (7 feet)
above the deepest load line if—
(1) The vessel is engaged on a short
international voyage as defined in
§ 171.010 of this subchapter; and
(2) The vessel is required by § 171.065
of this subchapter to have a factor of
subdivision of 0.5 or less.
[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 944, Jan. 10,
1996; CGD 96–041, 61 FR 50734, Sept. 27, 1996]

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Coast Guard, DHS

§ 170.295

the door frame should not be considered as contributing to the strength of
the bulkhead. Provision must also be
made to adequately support the thrust
bearings and other equipment that
may be mounted on the bulkhead or
deck.
(2) Sliding watertight door frames
must be either bolted or welded watertight to the bulkhead.
(i) If bolted, a suitable thin heat and
fire resistant gasket or suitable compound must be used between the bulkhead and the frame for watertightness.
The bulkhead plating must be worked
to a plane surface in way of the frame
when mounting.
(ii) If welded, caution must be exercised in the welding process so that the
door frame is not distorted.
(e) For each watertight door which is
in a required subdivision bulkhead, an
indicator light must be installed in the
pilothouse and at each other vessel operating station from which the door is
not visible. The indicator must show
whether the door is open or closed.

Subpart I—Free Surface
§ 170.285 Free surface correction for
intact stability calculations.
(a) When doing the intact stability
calculations required by this subchapter, the virtual increase in the vessel’s vertical center of gravity due to
liquids in tanks must be determined by
calculating—
(1) For each type of consumable liquid, the maximum free surface effect of
at least one transverse pair of wing
tanks or a single centerline tank; and
(2) The maximum free surface effect
of each partially filled tank containing
non-consumable liquids.
(b) For the purpose of paragraph
(a)(1) of this section, the tank or combination of tanks selected must be
those having the greatest free surface
effect.
§ 170.290 Free surface correction for
damage stability calculations.
(a) When doing the damage stability
calculations required by this subchapter, the virtual increase in the vessel’s vertical center of gravity due to
liquids in tanks must be determined by
calculating—
(1) For each type of consumable liquid, the free surface effect of at least
one transverse pair of wing tanks or a
single centerline tank; and
(2) The free surface effect of each partially filled tank containing other than
consumable liquids.
(b) For the purpose of paragraph
(a)(1) of this section, the tank or combination of tanks selected must be
those having the greatest free surface
effect.
(c) When doing the calculations in
paragraph (a) of this section, the free
surface effect of a liquid in a tank must
be determined by—
(1) Assuming the vessel is heeled five
degrees from the vertical; or
(2) Calculating the shift of the center
of gravity of the liquid in the tank by
the moment of transference method.

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 88–032, 56 FR 35828, July 29,
1991; CGD 85–080, 61 FR 944, Jan. 10, 1996;
USCG–2000–7790, 65 FR 58464, Sept. 29, 2000]

pmangrum on DSK3VPTVN1PROD with CFR

§ 170.275 Special
requirements
cargo space watertight doors.

for

(a) A door between cargo spaces—
(1) Must not be designed for remote
operation;
(2) Must be located as high as practicable; and
(3) Must be located as far inboard of
the side shell as practicable but in no
case closer to the side shell than onefifth of the beam of the vessel where
the beam is measured at right angles
to the centerline of the vessel at the
level of the deepest load line.
(b) If the door is accessible while the
ship is in operation, it must have installed a lock or other device that prevents unauthorized opening.
(c) Before installing a watertight
door in a cargo space, approval must be
obtained from the Commanding Officer, Marine Safety Center.

§ 170.295 Special consideration for free
surface of passive roll stabilization
tanks.
(a) The virtual increase in the
vertical center of gravity due to a liquid in a roll stabilization tank may be

[CGD 79–023, 48 FR 51010, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988]

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§ 170.295

46 CFR Ch. I (10–1–11 Edition)

calculated in accordance with paragraph (b) of this section if—
(1) The virtual increase in the
vertical center of gravity of the vessel
is calculated in accordance with
§ 170.285(a); and
(2) The slack surface in the roll stabilization tank is reduced during vessel
motions because of the shape of the
tank or the amount of liquid in the
tank.
(b) The virtual rise in the vertical
center of gravity calculated in accordance with § 170.285(a) for a stabilization
tank may be reduced in accordance
with the following equation:
E.F.S.=(K)(F.F.S.)
where—
E.F.S.=the effective free surface.
F.F.S.=the full free surface calculated in accordance with § 170.285(a).
K=the reduction factor calculated in accordance with paragraph (c) of this section.

pmangrum on DSK3VPTVN1PROD with CFR

(c) The factor (K) must be calculated
as follows:

(1) Plot (I/d)tan T on Graph 170.295
where—
(i) (I) is the moment of inertia of the
free surface in the roll tank;
(ii) (d) is the density of the liquid in
the roll tank; and
(iii) (T) is the angle of heel.
(2) Plot the moments of transference
of the liquid in the roll tank on Graph
170.295.
(3) Construct a line A on Graph
170.295 so that the area under line A between T = 0 and the angle at which the
deck edge is immersed or 28 degrees,
whichever is smaller, is equal to the
area under the curve of actual moments of transference between the
same angles.
(4) The factor (K) is calculated by determining the ratio of the ordinate of
line A to the ordinate of the curve of (I/
d)tan T, both measured at the angle at
which the deck edge is immersed or 28
degrees, whichever is smaller.

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§ 170.300

46 CFR Ch. I (10–1–11 Edition)

§ 170.300 Special consideration for free
surface of spoil in hopper dredge
hoppers.
The calculations required by this
subchapter for each self-propelled hopper dredge must include—
(a) The free surface effect of
consumable liquids and the free surface
effect of the dredged spoil in the hoppers; and
(b) Either of the following assumptions when performing the calculations
required by § 174.310(b) of this chapter:
(1) If the dredged spoil is assumed to
be jettisoned, the free surface of the
dredged spoil may be disregarded.
(2) If the dredged spoil is not assumed
to be jettisoned. the free surface of the
dredged spoil must be calculated.

171.072 Calculation of permeability for Type
II subdivision.
171.073 Treatment of stepped and recessed
bulkheads in Type II subdivision.
171.075 [Reserved]
171.080 Damage stability standards for vessels with Type I or Type II subdivision.

Subpart D—Additional Subdivision
Requirements
171.085 Collision bulkhead.
171.090 Aft peak bulkhead.
171.095 Machinery space bulkhead.
171.100 Shaft tunnels and stern tubes.
171.105 Double bottoms.
171.106 Wells in double bottoms.
171.108 Manholes in double bottoms.
171.109 Watertight floors in double bottoms.

Subpart E—Penetrations and Openings in
Watertight Bulkheads

[CGD 76–080, 54 FR 36977, Sept. 6, 1989]

PART 171—SPECIAL RULES PERTAINING TO VESSELS CARRYING
PASSENGERS
Subpart A—General
Sec.
171.001 Applicability.
171.010 Definitions.
171.012 Incorporation by reference.
171.015 Location of margin line.
171.017 One and two compartment standards
of flooding.

Subpart B—Intact Stability
171.045 Weight of passengers and crew.
171.050 Passenger heel requirements for a
mechanically propelled or a non-self propelled vessel.
171.052 Passenger heel requirements for pontoon vessels.
171.055 Intact stability requirements for a
monohull sailing vessel or a monohull
auxiliary sailing vessel.
171.057 Intact stability requirements for a
sailing catamaran.

pmangrum on DSK3VPTVN1PROD with CFR

Subpart C—Subdivision and Damage
Stability
171.060 Watertight subdivision: General.
171.065 Subdivision requirements—Type I.
171.066 Calculation of permeability for Type
I subdivision.
171.067 Treatment of stepped and recessed
bulkheads in Type I subdivision.
171.068 Special considerations for Type I
subdivision for vessels on short international voyages.
171.070 Subdivision requirements—Type II.

171.110 Specific applicability.
171.111 Penetrations and openings in watertight bulkheads in vessels of 100 gross
tons or more.
171.112 Watertight door openings.
171.113 Trunks.
171.114 Penetrations and openings in watertight bulkheads in a vessel less than a
100 gross tons.

Subpart F—Openings in the Side of a Vessel Below the Bulkhead or Weather
Deck
171.115 Specific applicability.
171.116 Port lights.
171.117 Dead covers.
171.118 Automatic ventilators and side
ports.
171.119 Openings below the weather deck in
the side of a vessel less than 100 gross
tons.

Subpart G—Watertight Integrity Above the
Margin Line
171.120 Specific applicability.
171.122 Watertight integrity above the margin line in a vessel of 100 gross tons or
more.
171.124 Watertight integrity above the margin line in a vessel less than 100 gross
tons.

Subpart H—Drainage of Weather Decks
171.130 Specific applicability.
171.135 Weather deck drainage on a vessel of
100 gross tons or more.
171.140 Drainage of a flush deck vessel.
171.145 Drainage of a vessel with a cockpit.
171.150 Drainage of a vessel with a well
deck.
171.155 Drainage of an open boat.

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Coast Guard, DHS

§ 171.010

AUTHORITY: 46 U.S.C. 2103, 3306; E.O. 12234,
45 FR 58801, 3 CFR, 1980 Comp., p. 277; Department of Homeland Security Delegation
No. 0170.1.
SOURCE: CGD 79–023, 48 FR 51017, Nov. 4,
1983, unless otherwise noted.

Subpart A—General
§ 171.001

Applicability.

(a) Except as provided in paragraph
(d) of this section, this part applies to
passenger vessels inspected under subchapter K or H of this chapter, or a
passenger vessel the stability of which
is questioned by the Officer in Charge,
Marine Inspection (OCMI).
(b) Specific sections of this part also
apply to nautical school ships, sailing
school vessels and oceanographic vessels. The applicable sections are listed
in subparts C and D of part 173 of this
chapter.
(c) Specific sections of this part may
also apply to a small passenger vessel
inspected under subchapter T of this
chapter. The specific sections are listed
in subparts B and C of part 178 of this
chapter and in subpart B of part 179 of
this chapter.
(d) Unless permitted otherwise, a passenger vessel constructed on or after
January 1, 2009, and issued a SOLAS
Passenger Ship Safety Certificate must
meet the applicable requirements of
IMO Res. MSC.216(82) (incorporated by
reference, see § 171.012), instead of the
requirements of this part. For the purposes of this section, the applicable requirements of IMO Res. MSC.216(82) are
equivalent to the requirements of this
part when applied to such vessels.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 83–005, 51 FR 923, Jan. 9,
1986; CGD 95–012, 60 FR 48052, Sept. 18, 1995; 60
FR 50120, Sept. 28, 1995; CGD 85–080, 61 FR 944,
Jan. 10, 1996; USCG–2007–0030, 75 FR 78084,
Dec. 14, 2010]

pmangrum on DSK3VPTVN1PROD with CFR

§ 171.010

Definitions.

(a) Cockpit means an exposed recess
in the weather deck extending no more
than one-half of the vessel’s length
over deck (LOD) measured over the
weather deck.
(b) Deepest subdivision load line means
the waterline that corresponds to the
deepest draft permitted by the applica-

ble subdivision requirements in this
part.
(c) Equivalent plane bulkhead means a
bulkhead that is—
(1) Used in lieu of a recessed or
stepped bulkhead when doing the subdivision calculations required in this
part; and
(2) Located as shown in Figure
171.010(a).
(d) Ferry means a vessel that—
(1) Operates in other than ocean or
coastwise service;
(2) Has provisions only for deck passengers or vehicles, or both;
(3) Operates on a short run on a frequent schedule between two points
over the most direct water route;
(4) Offers a public service of a type
normally attributed to a bridge or tunnel.
(e) Freeing port means any direct
opening through the vessel’s bulwark
or hull to quickly drain overboard
water which has been shipped on exposed decks.
(f) Floodable length means the length
of a shell to shell segment of the vessel
that, when flooded, will sink and trim
the vessel until the margin line is tangent to the waterline.
(g) Flush deck means a continuous
weather deck located at the uppermost
sheer line of the hull.
(h) International voyage has the same
meaning provided for the term in
§ 70.05–10 of this chapter.
(i) Machinery space means, unless
otherwise prescribed by the Commandant for unusual arrangements,
the space extending from the molded
base line to the margin line and between the main transverse watertight
bulkheads bounding the following
spaces:
(1) Each space containing main and
auxiliary propelling machinery.
(2) Each space containing propulsion
boilers.
(3) Each space containing permanent
coal bunkers.
(j) Open boat means a vessel not protected from entry of water by means of
a complete deck, or by a combination
of a partial weather deck and superstructure which is seaworthy for the
waters upon which the vessel operates.

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46 CFR Ch. I (10–1–11 Edition)

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(k) Passenger space means a space
which is provided for the accommodation and use of passengers, other than
a baggage, store, provision or mail
room.
(l) Recessed bulkhead means a bulkhead that is recessed as shown by bulkhead B in Figure 171.010(b).
(m) Small passenger vessel means a
vessel of less than 100 gross tons—
(1) Carrying more than 6 passengers,
including at least one passenger for
hire;
(2) That is chartered with the crew
provided or specified by the owner or
owner’s representative and carrying
more than 6 passengers;
(3) That is chartered with no crew
provided or specified by the owner or
owner’s representative and carrying
more than 12 passengers; or

(4) That is a submersible vessel carrying at least one passenger for hire.
(n) Short international voyage means
an international voyage where—
(1) A vessel is not more than 200 nautical miles (370 kilometers) from a port
or place in which the passengers and
crew could be placed in safety; and
(2) The total distance between the
last port of call in the country in
which the voyage began and the final
port of destination does not exceed 600
nautical miles (1111 kilometers).
(o) Scupper means a pipe or tube of at
least 30 millimeters (1.25 inches) in diameter leading down from a deck or
sole and through the hull to drain
water overboard.
(p) Stepped bulkhead means a bulkhead that is stepped as shown by bulkhead A in Figure 171.010(b).

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§ 171.010

(q) Well deck means a weather deck
fitted with solid bulwarks that impede
the drainage of water over the sides or
an exposed recess in the weather deck
extending one-half or more of the

length of the vessel (LOD) measured
over the weather deck.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 944, Jan. 10,
1996]

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Coast Guard, DHS

§ 171.012

46 CFR Ch. I (10–1–11 Edition)

(b) A vessel with a continuous bulkhead
deck and insufficient sheer. If the average value of the sheer at the forward

for the Safety of Life At Sea, 1974, As
Amended
(IMO
Res.
MSC.216(82),
Adopted on 8 December 2006, incorporation by reference (IBR) approved for
§§ 171.001 and 171.080.
(2) Resolution MSC 267(85), Adoption
of the International Code on Intact
Stability, 2008 (2008 IS Code), Adopted
on 4 December 2008, IBR approved for
§ 171.050.
[USCG–2007–0030, 75 FR 78085, Dec. 14, 2010]

§ 171.015

Location of margin line.

(a) A vessel with a continuous bulkhead
deck and sufficient sheer. If the average
value of the sheer at the forward perpendicular (FP) and the after perpendicular (AP) is at least 12 inches (30.5
cm), the margin line must be located
no less than 3 inches (7.6 cm) below the
upper surface of the bulkhead deck at
side as illustrated in Figure 171.015(a).
TABLE 171.015
Average value of sheer at FP
and AP in inches (cm)

Required position of margin line below top of deck
amidships in inches (cm)

12 (30.5) ....................................
6 (15.2) ......................................
0 .................................................

3 (7.6)
6 (15.2)
9 (22.8)

perpendicular (FP) and the after perpendicular (AP) is less than 12 inches
(30.5 cm), the margin line must be a

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§ 171.012 Incorporation by reference.
(a) Certain material is incorporated
by reference into this part with the approval of the Director of the Federal
Register under 5 U.S.C. 552(a) and 1
CFR part 51. To enforce any edition
other than that specified in this section, the Coast Guard must publish a
notice of change in the FEDERAL REGISTER and the material must be available to the public. All approved material is available for inspection at the
National Archives and Records Administration (NARA). For information on
the availability of this material at
NARA, call 202–741–6030 or go to http://
www.archives.gov/federallregister/
codeloflfederallregulations/
ibrllocations.html. It is also available
for inspection at the Coast Guard, Office of Design and Engineering Standards, Naval Architecture Division (CG–
5212), 2100 2nd St., SW., Stop 7126,
Washington, DC 20593–7126, and is available from the sources listed below.
(b) International Maritime Organization (IMO), Publications Section, 4 Albert Embankment, London SE1 7SR,
United Kingdom, +44 (0)20 7735 7611,
http://www.imo.org/.
(1) Resolution MSC.216(82), Amendments to the International Convention

§ 171.015
below the surface of the bulkhead deck
amidships.
(3) Intermediate values not shown in
Table 171.015 must be interpolated.
(4) Figure 171.015(b) illustrates a margin line drawn in this manner.

(c) A vessel with a discontinuous bulkhead deck. A continuous margin line
must be drawn that is no more than 3

inches (7.6 cm) below the upper surface
of the bulkhead deck at side as illustrated in Figure 171.015(c).

EC01MR91.007

parabolic curve with the following
characteristics:
(1) The parabolic curve must be at
least 3 inches (7.6 cm) below the upper
surface of the bulkhead deck at the FP
and AP.
(2) The parabolic curve must be at
least the distance given in Table 171.015

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Coast Guard, DHS

§ 171.017

46 CFR Ch. I (10–1–11 Edition)

(d) A vessel with a discontinuous bulkhead deck where the side shell is carried
watertight to a higher deck. A contin-

uous margin line must be drawn as illustrated in Figure 171.015(d).

§ 171.017 One and two compartment
standards of flooding.

son, which is determined in accordance
with § 170.090 of this chapter.

(a) One compartment standard of flooding. A vessel is designed to a one compartment standard of flooding if the
margin line is not submerged when the
total buoyancy between each set of two
adjacent main transverse watertight
bulkheads is lost.
(b) Two compartment standard of flooding. A vessel is designed to a two compartment standard of flooding if the
margin line is not submerged when the
total buoyancy between each set of
three adjacent main transverse watertight bulkheads is lost.

[USCG–2007–0030, 75 FR 78085, Dec. 14, 2010]

Subpart B—Intact Stability
of

passengers

and

(a) This section applies to each vessel, regardless of when constructed.
(b) Compliance with the intact stability requirements applicable to each
vessel, using a total weight of passengers and crew carried, is based upon
an Assumed Average Weight per Per-

(a) Each mechanically propelled or
non-self propelled vessel other than a
pontoon vessel must be shown by design calculations, in each condition of
loading and operation, to have a
metacentric height (GM) in feet (meters) of not less than the value given
by the following equation:
GM = [(W/D)(2⁄3)(b)]/(tan(T))
Where—
D = displacement of the vessel in long (metric) tons.
W = total weight in long (metric) tons of persons other than required crew, including
personal effects of those persons expected
to be carried on the vessel.
T = 14 degrees or the angle of heel at which
the deck edge is first submerged, whichever is less; and
b = distance in feet (meters) from the centerline of the vessel to the geometric center
of the passenger deck on one side of the
centerline.

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§ 171.045 Weight
crew.

§ 171.050 Passenger heel requirements
for a mechanically propelled or a
non-self propelled vessel.

Coast Guard, DHS

§ 171.055

(b) The criteria specified in paragraph (a) of this section are limited in
application to the conditions of loading
and operation of vessels for which the
righting arm (GZ) at the angle (T), calculated after the vessel is permitted to
trim free until the trimming moment
is zero, is not less than the minimum
metacentric height (GM) calculated in
paragraph (a) of this section multiplied
by sin(T). In conditions not meeting
this requirement, the Coast Guard Marine Safety Center requires calculations in addition to those in this section.
(c) A vessel that complies with the
requirements for passenger ships contained in the International Code of Intact Stability, 2008 (2008 IS Code) (incorporated by reference, see § 171.012)
need not comply with paragraphs (a) or
(b) of this section. Vessels complying
with the 2008 IS Code must use the Assumed Average Weight per Person obtained according to § 170.090 of this title
to be exempt from the other requirements of this section.

§ 171.052 Passenger heel requirements
for pontoon vessels.
(a) Each pontoon vessel, in each condition of loading and operation, must
have an area under the righting arm
curve from the angle of equilibrium to
an
angle
of
40
degrees,
the
downflooding angle, or the angle of the
maximum righting arm, whichever is
less, of at least:
(1) For operation on exposed or partially protected waters—
(i) 10 foot-degrees with a crowding
density of 5 square feet per person (2.15
persons per square meter); and
(ii) 7 foot-degrees with a crowding
density of 2 square feet per person (5.38
persons per square meter); and
(2) For operation on protected
waters—
(i) 5 foot-degrees with a crowding
density of 5 square feet per person (2.15
persons per square meter); and
(ii) 2 foot-degrees with a crowding
density of 2 square feet per person (5.38
persons per square meter).
(b) When assessing compliance with
the criteria of this section, passengers
are assumed to be distributed in all
areas accessible to passengers so as to

[USCG–2007–0030, 75 FR 78085, Dec. 14, 2010]

§ 171.055 Intact stability requirements
for a monohull sailing vessel or a
monohull auxiliary sailing vessel.
(a) Except as specified in paragraph
(b) of this section, each monohull sailing vessel and auxiliary sailing vessel
must be shown by design calculations
to meet the stability requirements in
this section.
(b) Additional or different stability
requirements may be needed for a vessel of unusual form, proportion, or rig.
The additional requirements, if needed,
will be prescribed by the Commandant.
(c) Each vessel must have positive
righting arms in each condition of
loading and operation from—
(1) 0 to at least 70 degrees of heel for
service on protected or partially protected waters; and
(2) 0 to at least 90 degrees of heel for
service on exposed waters.
(d) Each vessel must be designed to
satisfy the following equations:
(1) For a vessel in service on protected or partially protected waters—

1000(W)HZA
(A)(H)

1000(W)HZB
(A)(H)

1000(W)HZC
(A)(H)

≥X

≥Y

≥Z

where—
X=1.0 long tons/sq. ft. (10.9 metric tons/sq.
meter).
Y=1.1 long tons/sq. ft. (12.0 metric tons/sq.
meter).
Z=1.25 long tons/sq. ft. (13.7 metric tons/sq.
meter).

(2) For a vessel on exposed waters—

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[USCG–2007–0030, 75 FR 78085, Dec. 14, 2010]

produce the most unfavorable combination of heel and trim.

§ 171.055

46 CFR Ch. I (10–1–11 Edition)

1000(W)HZA
(A)(H)

1000(W)HZB
(A)(H)

(ii) The first intercept shown on
Graph 171.055(b) must occur at the
angle of heel corresponding to the
angle at which deck edge immersion
first occurs.
(4) Plot an assumed heeling arm
curve on Graph 171.055(c) that satisfies
the following conditions:
(i) The assumed heeling arm curve
must be defined by the equation—

≥X

≥Y

HZ=HZB cos2 (T)

1000(W)HZC
(A)(H)

where—
HZ=heeling arm.
HZB=heeling arm at 0 degrees of heel.
T=angle of heel.

≥Z

where—
HZA, HZB, and HZC are calculated in the
manner specified in paragraph (e) or (f) of
this section.
X=1.5 long tons/sq. ft. (16.4 metric tons/sq.
meter).
Y=1.7 long tons/sq. ft. (18.6 metric tons/sq.
meter).
Z=1.9 long tons/sq. ft. (20.8 metric tons/sq.
meter).
A=the projected lateral area or silhouette in
square feet (meters) of the portion of the
vessel above the waterline computed with
all sail set and trimmed flat. Sail overlap
areas need not be included except parachute type spinnakers which are to be
added regardless of overlap.
H=the vertical distance in feet (meters) from
the center of A to the center of the underwater lateral area or approximately to the
one-half draft point.
W=the displacement of the vessel in long
(metric) tons.

(e) Except as provided in paragraph
(f) of this section, HZA, HZB, and HZC
must be determined as follows for each
condition of loading and operation:
(1) Plot the righting arm curve on
Graphs 171.055 (b), (c), and (d) or (e).
(2) If the angle at which the maximum righting arm occurs is less than
35 degrees, the righting arm curve
must be truncated as shown on Graph
171.055(a).
(3) Plot an assumed heeling arm
curve on Graph 171.055(b) that satisfies
the following conditions:
(i) The assumed heeling arm curve
must be defined by the equation—

where—
HZ=heeling arm.
HZA=heeling arm at 0 degrees of heel.
T=angle of heel.

HZ=HZC cos2 (T)
where—
HZ=heeling arm.
HZC=heeling arm at 0 degrees of heel.
T=angle of heel.

(ii) The area under the assumed heeling arm curve between the angles of 0
and 90 degrees must be equal to the
area under the righting arm curve between 0 degrees and—
(A) 90 degrees if the righting arms
are positive to an angle less than or
equal to 90 degrees; or
(B) The largest angle corresponding
to a positive righting arm but no more
than 120 degrees if the righting arms
are positive to an angle greater than 90
degrees.
(6) The values of HZA, HZB, and HZC
are read directly from Graphs 171.055
(b), (c), and (d) or (e).
(f) For the purpose of this section,
the downflooding angle means the static angle from the intersection of the
vessel’s centerline and waterline in
calm water to the first opening that
cannot be rapidly closed watertight.
(g) HZB and, if the righting arms are
positive to an angle of 90 degrees or
greater, HZC may be computed from
the following equation:

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HZ=HZA cos2 (T)

(ii) The area under the assumed heeling arm curve between 0 degrees and
the downflooding angle or 60 degrees,
whichever is less, must be equal to the
area under the righting arm curve between the same limiting angles.
(5) Plot an assumed heeling arm
curve on Graph 171.055 (d) or (e) that
satisfies the following conditions:
(i) The assumed heeling arm curve
must be defined by—

Coast Guard, DHS

§ 171.055

((T / 2) +14.3sin 2T)

pmangrum on DSK3VPTVN1PROD with CFR

where—
I=the area under the righting arm curve to—
(1) the downflooding angle or 60 degrees,
whichever is less, when computing HZB;
or

EC01MR91.013

HZB (or HZC) =

(2) the largest angle corresponding to a
positive righting arm or 90 degrees,
whichever is greater, but no greater than
120 degrees when computing HZC.
T=the downflooding angle or 60 degrees,
whichever is less, when computing HZB or
90 degrees when computing HZC.

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I

46 CFR Ch. I (10–1–11 Edition)

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§ 171.055

§ 171.055

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46 CFR Ch. I (10–1–11 Edition)

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§ 171.055

Coast Guard, DHS

§ 171.057

[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as amended by CGD 83–005, 51, FR 924, Jan. 9, 1986]

Where—
B=the distance between hull centerlines in
meters (feet).
As=the maximum sail area in square meters
(square feet).
Hc=the height of the center of effort of the
sail area above the deck, in meters (feet).

0.1( W )B
≥X
( As)( Hc)
Where—
B=the distance between hull centerlines in
meters (feet).

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0.1( W )B
≥X
( As)( Hc)

(b) A sailing vessel that operates on
partially protected or exposed waters
must be designed to satisfy the following equation:

ER10JA96.007

(a) A sailing vessel that operates on
protected waters must be designed to
satisfy the following equation:

W=the total displacement of the vessel, in
kilograms (pounds).
X=4.88 kilograms/square meter (1.0 pounds/
square foot).

EC01MR91.017

§ 171.057 Intact stability requirements
for a sailing catamaran.

§ 171.060

46 CFR Ch. I (10–1–11 Edition)

As=the maximum sail area in square meters
(square feet).
Hc=the height of the center of effort of the
sail area above the deck, in meters (feet).
W=the total displacement of the vessel, in
kilograms (pounds).
X=7.32 kilograms/square meter (1.5 pounds/
square foot).
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 83–005, 51 FR 924, Jan. 9,
1986; CGD 85–080, 61 FR 944, Jan. 10, 1996]

(b) The factor of subdivision used to
determine compliance with paragraph
(a) of this section must be the smaller
of 0.5 or the value determined from
Table 171.065(a) if—
(1) The vessel is 430 feet (131 meters)
or more in LBP; and
(2) The greater of the values of Y as
determined by the following equations
equals or exceeds the value of X in
Table 171.065(b):

Subpart C—Subdivision and
Damage Stability
§ 171.060
eral.

Y=

V

Watertight subdivision: Gen-

(a) Each of the following vessels must
be shown by design calculations to
comply with the requirements in
§§ 171.065 through 171.068 for Type I subdivision:
(1) Each vessel 100 gross tons or more
on an international voyage: and
(2) Each vessel 150 gross tons or more
in ocean service.
(b) Each vessel not described in paragraph (a) of this section must be shown
by design calculations to comply with
the requirements in §§ 171.070 to 171.073
for Type II subdivision.
(c) Except as allowed in § 171.070(c),
each vessel must have a collision bulkhead.
(d) Each double-ended ferry that is
required by paragraph (c) of this section to have a collision bulkhead must
also have a second collision bulkhead.
One collision bulkhead must be located
in each end of the vessel.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by USCG–2007–0030, 75 FR 78085,
Dec. 14, 2010]

§ 171.065 Subdivision requirements—
Type I.
(a) Except as provided in paragraphs
(c) and (f) of this section, the separation between main transverse watertight bulkheads on a vessel, other than
one described in paragraph (b) of this
section, must not exceed—
(floodable length)×(factor of subdivision)
where—
the factor of subdivision is listed under FS in
Table 171.065(a).

or

Y = (M + 2P1)/(V + P1¥P)
where—
M, V, and P have the same value as listed in
Table 171.065(a); and
P1=the smaller of the following:
(i) 0.6LN (0.056LN) where—
N=the total number of passengers; and
L=LBP in feet (meters).
(ii) The greater of the following:
(A) 0.4LN (0.037LN).
(B) The sum of P and the total volume of
passenger spaces above the margin
line.

(c) The distance A in Figure 171.065
between main transverse watertight
bulkheads may exceed the maximum
allowed by paragraphs (a) or (b) of this
section if each of the distances B and C
between adjacent main transverse watertight bulkheads in Figure 171.065
does not exceed the smaller of the following:
(1) The floodable length.
(2) Twice the separation allowed by
paragraphs (a) or (b) of this section.
(d) In each vessel 330 feet (100 meters)
or more in LBP, one of the main transverse watertight bulkheads aft of the
collision bulkhead must be located at a
distance from the forward perpendicular that is not greater than the
maximum separation allowed by paragraph (a) or (b) of this section.
(e) The minimum separation between
two adjacent main transverse watertight bulkheads must be at least 10 feet
(3.05 meters) plus 3 percent of the LBP
of the vessel, or 35 feet (10.7 meters),
whichever is less.
(f) The maximum separation of bulkheads allowed by paragraphs (a) or (b)
of this section may be increased by the

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(M + 2P)

Coast Guard, DHS

§ 171.065

amount allowed in paragraph (g) of this
section if—
(1) The space between two adjacent
main transverse watertight bulkheads
contains internal watertight volume;
and

Increase in separation =

(2) After the assumed side damage
specified in paragraph (h) of this section is applied, the internal watertight
volume will not be flooded.
(g) For the purpose of paragraph (f) of
this section, the allowable increase in
separation is as follows:

"total volume of allowed local subdivision"
"transverse sectional area at center of compartment"

where—

TABLE 171.065(a) (ENGLISH UNITS)
Vessel length (LBP)

Criterion numeral (CN)

A

Vessel length greater than
392 feet.

CN less than or equal to
23.
CN greater than 23 and
less than 123.
CN greater than or equal
to 123.
CN less than or equal to
S.
CN greater than S and
less than 123.

1

CN greater than or equal
to 123.

B

..........................................

1

Vessel length greater than
or equal to 200 feet and
less than or equal to
392 feet.

Vessel length less than
200 feet.

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F1
B

F2

Where—
FS=the factor of subdivision.
CN=60((M+2P)/V)+30000(N/L2)
A=(190/(L¥160))+0.18
B=(94/(L¥85))+0.18
F1=A¥((A¥B)(CN¥23)/100)
S=(10904¥25L)/48
F2=1¥((1¥B)(CN¥S)/(123¥S))
L=the length of the vessel (LBP) in feet.
M=the sum of the volume of the machinery space and the
volumes of any fuel tanks which are located above the inner
bottom forward or aft of the machinery space in cubic feet.
P=the volume of passenger spaces below the margin line.
V=the volume of the vessel below the margin line.
N=the number of passengers that the vessel is to be certificated to carry.

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(h) The assumed extents of side damage are as follows:
(1) The longitudinal extent of damage
must be assumed to extend over a
length equal to the minimum spacing
of bulkheads specified in paragraph (e)
of this section.
(2) The transverse extent of damage
must be assumed to penetrate a distance from the shell plating equal to
one-fifth the maximum beam of the
vessel and at right angles to the centerline at the level of the deepest subdivision load line.
(3) The vertical extent of damage must
be assumed to extend vertically from
the baseline to the margin line.
(i) The maximum separation between
the following bulkheads must not exceed the maximum separation between
main transverse watertight bulkheads:
(1) The collision bulkhead and the
first main transverse watertight bulkhead aft of the collision bulkhead; and
(2) The last main transverse watertight bulkhead and the aftermost point
on the bulkhead deck.
(j) The minimum separation between
the following bulkheads must not be
less than the minimum separation between main transverse watertight
bulkheads:
(1) The collision bulkhead and the
first main transverse watertight bulkhead aft of the collision bulkhead; and
(2) The last main transverse watertight bulkhead and the aftermost point
on the bulkhead deck.

EC01MR91.020

pmangrum on DSK3VPTVN1PROD with CFR

‘‘total volume of allowed local subdivision’’
is determined by calculating the unflooded
volume on each side of the centerline and
multiplying the smaller volume by two.

§ 171.066

46 CFR Ch. I (10–1–11 Edition)

TABLE 171.065(a) (METRIC UNITS)
Vessel length (LBP)

Criterion numeral (CN)

Vessel length greater than
120 meters.

Vessel length greater than
or equal to 61 meters
and less than or equal
to 120 meters.

Vessel length less than 61
meters.

FS

CN lesthan or equal to 23
CN greater than 23 and
less than 123.
CN greater than or equal
to 123.

A
F1

CN less than or equal to
S.
CN greater than S and
less than 123.

1

CN greater than or equal
to 123.

B

..........................................

1

B

F2

Where—
FS=the factor of subdivision.
CN=60((M+2P)/V)+2787(N/L2)
A=(58/(L–49))+0.18
B=(29/(L–26))+0.18
F1=A¥((A¥B)(CN¥23)/100)
S=(3323.5¥25L)/14.6
F2=1¥((1¥B)(CN¥S)/(123¥S))
L=the length of the vessel (LBP) in meters.
M=the sum of the volume of the machinery space and the
volumes of any fuel tanks which are located above the inner
bottom forward or aft of the machinery space in cubic meters.
P=the volume of passenger spaces below the margin line.
V=the volume of the vessel below the margin line.
N=the number of passengers that the vessel is to be certificated to carry.

TABLE 171.065(b)—TABLE OF X
Vessel LBP in feet (meters)
430
440
450
460
470
480
490
500
510
520
530
540
550
554

(131)
(134)
(137)
(140)
(143)
(146)
(149)
(152)
(155)
(158)
(162)
(165)
(168)
(169)

...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
and up .......................................................

1 Interpolate

X1
1.336
1.285
1.230
1.174
1.117
1.060
1.002
0.944
0.885
0.826
0.766
0.706
0.645
0.625

for intermediate values.

pmangrum on DSK3VPTVN1PROD with CFR

[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by USCG–2007–0030, 75 FR 78085,
Dec. 14, 2010]

§ 171.066 Calculation of permeability
for Type I subdivision.
(a) Except as prescribed in paragraph
(b) of this section, the following
permeabilities must be used when
doing the calculations required to demonstrate compliance with § 171.065(a),
(b), and (c):
(1) When doing calculations required
to
demonstrate
compliance
with
§ 171.065(a) and (b), the uniform average

permeability given by the formulas in
Table 171.066 must be used.
(2) When doing calculations required
to demonstrate that compartments on
opposite sides of a main transverse watertight bulkhead that bounds the machinery space comply with § 171.065(c),
the mean of the uniform average
permeabilities determined from Table
171.066 for the two compartments must
be used.
(b) If an average permeability can be
calculated that is less than that given
by the formulas in Table 171.066, the
lesser value may be substituted if approved by the Commanding Officer,
Marine Safety Center. When determining this lesser value, the following
permeabilities must be used:
(1) 95% for passenger, crew, and all
other spaces that, in the full load condition, normally contain no cargo,
stores, provisions, or mail.
(2) 60% for cargo, stores, provisions,
or mail spaces.
(3) 85% for spaces containing machinery.
(4) Values approved by the Commanding Officer, Marine Safety Center
for double bottoms, oil fuel, and other
tanks.
(c) In the case of unusual arrangements, the Commanding Officer, Marine Safety Center may require a detailed calculation of average permeability for the portions of the vessel
forward or aft of the machinery spaces.
When doing these calculations, the
permeabilities specified in paragraph
(b) of this section must be used.
(d) When calculating permeability,
the total volume of the ‘tween deck
spaces between two adjacent main
transverse watertight bulkheads that
contains any passenger or crew space
must be regarded as passenger space
volume, except that the volume of any
space that is completely enclosed in
steel buldheads and is not a crew or
passenger space may be excluded.
TABLE 171.066—TABLE OF UNIFORM AVERAGE
PERMEABILITIES
Uniform average
permeability

Location

Machinery space ........................................

10 (a¥c)
85+lllll
v
35(a)

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Coast Guard, DHS

§ 171.067

TABLE 171.066—TABLE OF UNIFORM AVERAGE
PERMEABILITIES—Continued
Uniform average
permeability

Location
Volume forward of machinery space ..........

Volume aft of machinery space ..................

63+lll
v
35(a)
63+lll
v

For each location specified in this table—
a=volume below the margin line of all spaces that, in the
full load condition, normally contain no cargo, baggage,
stores, provisions, or mail.
c=volume below the margin line of the cargo, stores, provisions, or mail spaces within the limits of the machinery space.
v=total volume below the margin line.

[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988]

§ 171.067 Treatment of stepped and recessed bulkheads in Type I subdivision.

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(a) For the purpose of this section—
(1) The main transverse watertight
bulkhead immediately forward of a
stepped bulkhead is referred to as bulkhead 1; and
(2) The main transverse watertight
bulkhead immediately aft of the
stepped bulkhead is referred to as bulkhead 3.
(b) If a main transverse watertight
bulkhead is stepped, it and bulkheads 1
and 3 must meet one of the following
conditions:
(1) The separation between bulkheads
1 and 3 must not exceed the following:
(i) If the factor of subdivision (FS)
determined from § 171.065 (a) or (b) is
greater than 0.9, the distance between
bulkheads 1 and 3 must not exceed the
maximum separation calculated to
demonstrate compliance with § 171.065.
(ii) If the factor of subdivision is 0.9
or less, the distance between bulkheads

1 and 3 must not exceed 90% of the
floodable length or twice the maximum
bulkhead separation calculated to demonstrate compliance with § 171.065,
whichever is smaller.
(2) Additional watertight bulkheads
must be located as shown in Figure
171.067(a) so that distances A, B, C, and
D, illustrated in Figure 171.067(a), satisfy the following:
(i) Distances A and B must not exceed the maximum spacing allowed by
§ 171.065.
(ii) Distances C and D must not be
less than the minimum separation prescribed by § 171.065(e).
(3) The distance A, illustrated in Figure 171.067(b), must not exceed the
maximum
length
determined
in
§ 171.065 corresponding to a margin line
taken 3 inches (7.6 cm) below the step.
(c) A main transverse bulkhead may
not be recessed unless all parts of the
recess are inboard from the shell of the
vessel a distance A as illustrated in
Figure 171.067(c).
(d) Any part of a recess that lies outside the limits defined in paragraph (c)
of this section must be treated as a
step in accordance with paragraph (b)
of this section.
(e) The distance between a main
transverse watertight bulkhead and
the transverse plane passing through
the nearest portion of a recessed bulkhead must be greater than the minimum
separation
specified
by
§ 171.065(e).
(f) If a main transverse bulkhead is
stepped or recessed, equivalent plane
bulkheads must be used in the calculations required to demonstrate compliance with § 171.065.

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§ 171.067

Coast Guard, DHS

§ 171.068

(a) The calculations done to demonstrate compliance with § 171.065 for a
vessel that makes short international
voyages and is permitted under § 75.10–
10 of this chapter to carry a number of

persons on board in excess of the lifeboat capacity must—
(1) Assume the uniform average
permeabilities given in Table 171.068 in
lieu of those in Table 171.066; and
(2) Use a factor of subdivision (FS)
that is the smaller of the following:
(i) The value from Table 171.065(a).
(ii) 0.50.

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§ 171.068 Special considerations for
Type I subdivision for vessels on
short international voyages.

§ 171.070

46 CFR Ch. I (10–1–11 Edition)

(b) For a vessel less than 300 feet (91
meters) in length, the Commanding Officer, Marine Safety Center may approve the separation of main transverse watertight bulkheads greater
than that permitted by paragraph (a)
of this section if—
(1) The shorter separation is impracticable; and
(2) The separation is the smallest
that is practicable.
(c) In the case of ships less than 180
feet (55 meters) in length, the Commanding Officer, Marine Safety Center
may approve a further relaxation in
the bulkhead spacing. However, in no
case may the separation be large
enough to prevent the vessel from complying with the flooding requirements
for Type II subdivision in § 171.070.
TABLE 171.068—TABLE OF UNIFORM AVERAGE
PERMEABILITIES
Uniform average
permeability

Location

Machinery Space ......................................

10 (a¥c)
85+llll
v

Volume Forward of Machinery Space ......

35(b)
95¥ll
v

Volume Aft of Machinery Space ...............

35(b)
95¥lll
v

For each location specified in this table—
a=volume below the margin line of all spaces that, in the
full load condition, normally contain no cargo, baggage,
stores, provisions, or mail.
b=volume below the margin line and above the tops of
floors, inner bottoms, or peak tanks of coal or oil fuel bunkers,
chain lockers, fresh water tanks, and of all spaces that, in the
full load condition, normally contain stores, baggage, mail,
cargo, or provisions. If cargo holds are not occupied by cargo,
no part of the cargo space is to be included in this volume.
c=volume below the margin line of the cargo, stores, provisions, or mail spaces within the limits of the machinery space.
v=total volume below the margin line.

pmangrum on DSK3VPTVN1PROD with CFR

[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988]

§ 171.070 Subdivision requirements—
Type II.
(a) Each vessel, except a ferry vessel,
must be designed so that, while in each
condition of loading and operation, it
complies with the standard of flooding
specified in Table 171.070(a).
(b) Except as provided in paragraph
(c), each ferry vessel must be designed
so that, while in each condition of
loading and operation, it meets the

standard of flooding specified in Table
171.070(b).
(c) A ferry vessel described in paragraph (d) of this section need not meet
the standard of flooding specified in
Table 171.070(b), except that a ferry
vessel in Great Lakes service must at
least have a collision bulkhead.
(d) Paragraph (c) of this section applies to a ferry vessel that—
(1) Is 150 feet (46 meters) or less in
length; and
(2) Has sufficient air tankage, or
other internal buoyancy to float the
vessel with no part of the margin line
submerged when the vessel is completely flooded. If foam is used to comply with this paragraph, it must be installed in accordance with the requirements in § 170.245 of this subchapter.
(e) Except as specified in paragraph
(f) of this section, each main transverse
watertight bulkhead must be spaced as
follows:
(1) Unless otherwise permitted, if the
LBP of the vessel is 143 feet (43.5 meters) or more, or the vessel makes
international voyages, each main
transverse watertight bulkhead must
be at least 10 feet (3 meters) plus 3 percent of the vessel’s LBP from—
(i) Every other main transverse watertight bulkhead;
(ii) The collision bulkhead; and
(iii) The aftermost point on the bulkhead deck.
(2) If the LBP of the vessel is less
than 143 feet (43.5 meters) and the vessel does not make international voyages, each main transverse watertight
bulkhead must be no less than 10 percent of the vessel’s LBP or 6 feet (1.8
meters), whichever is greater, from—
(i) Every other main transverse watertight bulkhead;
(ii) The collision bulkhead; and
(iii) The aftermost point on the bulkhead deck.
(f) If a vessel is required by § 171.060
to have a collision bulkhead in each
end of the vessel, then each main
transverse watertight bulkhead must
be no less than the distance specified in
paragraph (e) of this section from—
(1) Every other main transverse watertight bulkhead; and
(2) Each collision bulkhead.

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Coast Guard, DHS

§ 171.080

TABLE 171.070(a)—STANDARD OF FLOODING

Passengers carried

Part of vessel

Standard of
flooding
(compartments)

400 or less ............

All ............................................

1

401 to 600 ............

All of the vessel forward of the
first MTWB aft of the collision bulkhead..
All remaining portions of the
vessel.

2

601 to 800 ............

801 to 1000 ..........

More than 1000 ....

All of the vessel forward of the
first MTWB that is aft of a
point 40% of the vessel’s
LBP aft of the forward perpendicular.
All remaining portions of the
vessel.

1

2

1

All of the vessel forward of the
first MTWB that is aft of a
point 60% of the vessel’s
LBP aft of the forward
prependicular..
All remaining portions of the
vessel.

2

All ............................................

2

1

TABLE 171.070(b)—STANDARD OF FLOODING
FOR FERRY VESSELS

150 feet (46 meters)
or less.

Greater than 150 feet
(46 meters) and
less than or equal
to 200 feet (61 meters).

pmangrum on DSK3VPTVN1PROD with CFR

Greater than 200 feet
(61 meters).

Part of vessel

When doing calcualtions to show
compliance with § 171.070, the following
uniform average permeabilities must
be assumed:
(a) 85 percent in the machinery space.
(b) 60 percent in the following spaces:
(1) Tanks that are normally filled
when the vessel is in the full load condition.
(2) Chain lockers.
(3) Cargo spaces.
(4) Stores spaces.
(5) Mail or baggage spaces.
(c) 95 percent in all other spaces.
§ 171.073 Treatment of stepped and recessed bulkheads in Type II subdivision.

Where for this table‘‘MTWB’’ means main transverse watertight bulkhead; and
‘‘Standard of Flooding‘‘ is explained in § 171.017 of this
subchapter.

Vessel length

§ 171.072 Calculation of permeability
for Type II subdivision.

Standard of
flooding
(compartments)

All ......................................

1

All of the vessel forward of
the first MTWB aft of the
collision bulkhead.
All of the vessel aft of the
first MTWB forward of
the aft peak bulkhead.

2

(a) A main transverse watertight
bulkhead may not be stepped unless additional watertight bulkheads are located as shown in Figure 171.067(a) so
that the distances A, B, C, and D illustrated in Figure 171.067(a) comply with
the following:
(1) A and B must not exceed the maximum bulkhead spacing that permits
compliance with § 171.070; and
(2) C and D must not be less than the
minimum
spacing
specified
in
§ 171.070(e).
(b) A main transverse watertight
bulkhead may not be recessed unless
all parts of the recess are inboard from
the shell of the vessel as illustrated in
Figure 171.067(c).
(c) If a main transverse watertight
bulkhead is recessed or stepped, an
equivalent plane bulkhead must be
used in the calculations required by
§ 171.070.

2

§ 171.075

All remaining portions of
the vessel.

1

All ......................................

2

Where for this table—
‘‘MTWB’’ means main transverse watertight bulkhead; and
‘‘Standard of Flooding’’ is explained in § 171.017 of this
subchapter.

[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by USCG–2007–0030, 75 FR 78085,
Dec. 14, 2010]

[Reserved]

§ 171.080 Damage stability standards
for vessels with Type I or Type II
subdivision.
(a) Calculations. Each vessel with
Type I or Type II subdivision must be
shown by design calculations to meet
the survival conditions in paragraph
(e), (f), or (g) of this section in each
condition of loading and operation assuming the extent and character of
damage specified in paragraph (b) of
this section.

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§ 171.080

46 CFR Ch. I (10–1–11 Edition)

(b) Extent and character of damage.
For the purpose of paragraph (a) of this
section, design calculations must assume that the damage—
(1) Has the character specified in
Table 171.080(a); and
(2) Consists of a penetration having
the dimensions specified in Table
171.080(a) except that, if the most disabling penetration would be less than
the penetration described in the table,
the smaller penetration must be assumed.
(c) Permeability. When doing the calculations required in paragraph (a) of
this section, the permeability of each
space must be calculated in a manner
approved by the Commanding Officer,
Marine Safety Center or be taken from
Table 171.080(c).
(d) Definitions. For the purposes of
paragraphs (e) and (f) of this section,
the following definitions apply:
(1) New vessel means a vessel—
(i) For which a building contract is
placed on or after April 15, 1996;
(ii) In the absence of a building contract, the keel of which is laid, or
which is at a similar stage of construction, on or after April 15, 1996;
(iii) The delivery of which occurs on
or after January 1, 1997;
(iv) Application for the reflagging of
which is made on or after January 1,
1997; or
(v) That has undergone—
(A) A major conversion for which the
conversion contract is placed on or
after April 15, 1996;
(B) In the absence of a contract, a
major conversion begun on or after
April 15, 1996; or
(C) A major conversion completed on
or after January 1, 1997.
(2) Existing vessel means other than a
new vessel.
(3) Watertight means capable of preventing the passage of water through
the structure in any direction under a
head of water for which the surrounding structure is designed.
(4) Weathertight means capable of preventing the penetration of water, even
boarding seas, into the vessel in any
sea condition.
(e) Damage survival for all existing vessels except those vessels authorized to
carry more than 12 passengers on an
international voyage requiring a SOLAS

Passenger Ship Safety Certificate. An existing vessel is presumed to survive assumed damage if it meets the following
conditions in the final stage of flooding:
(1) On a vessel required to survive assumed damage with a longitudinal extent of 10 feet (3 meters) plus 0.03L, the
final angle of equilibrium must not exceed 7 degrees after equalization, except that the final angle may be as
large as 15 degrees if—
(i) The vessel is not equipped with
equalization or is equipped with fully
automatic equalization; and
(ii) The Commanding Officer, Marine
Safety Center approves the vessel’s
range of stability in the damaged condition.
(2) On a vessel required to survive assumed damage with a longitudinal extent of 20 feet (6.1 meters) plus 0.04L,
the angle of equilibrium must not exceed 15 degrees after equalization.
(3) The margin line may not be submerged at any point.
(4) The vessel’s metacentric height
(GM) must be at least 2 inches (5 cm)
when the vessel is in the upright position.
(f) Damage survival for all new vessels
except those vessels authorized to carry
more than 12 passengers on an international voyage requiring a SOLAS Passenger Ship Safety Certificate. A new vessel is presumed to survive assumed
damage if it is shown by calculations
to meet the conditions set forth in
paragraphs (f) (1) through (7) of this
section in the final stage of flooding
and to meet the conditions set forth in
paragraphs (f) (8) and (9) of this section
in each intermediate stage of flooding.
For the purposes of establishing boundaries to determine compliance with the
requirements in paragraphs (f) (1)
through (9), openings that are fitted
with weathertight closures and that
are not submerged during any stage of
flooding
will
not
be
considered
downflooding points.
(1) Each vessel must have positive
righting arms for a minimum range beyond the angle of equilibrium as follows:
Required
range
(degrees)

Vessel service
Exposed waters, oceans, or Great Lakes winter ..

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15

Coast Guard, DHS

§ 171.080
Required
range
(degrees)

Vessel service
Partially protected waters or Great Lakes summer
Protected waters ....................................................

10
5

(2) No vessel may have any opening
through which downflooding can occur
within the minimum range specified by
paragraph (f)(1) of this section.
(3) Each vessel must have an area
under each righting-arm curve of at
least 0.015 meter-radians, measured
from the angle of equilibrium to the
smaller of the following angles:
(i) The angle at which downflooding
occurs.
(ii) The angle of vanishing stability.
(4) Except as provided by paragraph
(f)(5) of this section, each vessel must
have within the positive range the
greater of a righting arm (GZ) equal to
or greater than 0.10 meter or a GZ as
calculated using the formula:

⎛ Heeling Moment
⎞
GZ( m ) = C⎜
+ 0.04⎟
⎝
⎠
Δ
where—
C=1.00 for vessels on exposed waters, oceans,
or Great Lakes winter;
C=0.75 for vessels on partially protected
waters or Great Lakes summer;
C=0.50 for vessels on protected waters;
D=intact displacement; and
Heeling moment=greatest of the heeling moments as calculated in paragraphs (f)(4) (i)
through (iv) of this section.

(i) The passenger heeling moment is
calculated using the formula:
Passenger Heeling Moment=0.5 (n w b)

(ii) The heeling moment due to asymmetric escape routes for passengers, if
the vessel has asymmetric escape
routes for passengers, is calculated assuming that—
(A) The weight of each passenger is
the weight used for calculations as determined in accordance with § 170.090(c)
of this chapter;

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where—
n=number of passengers;
w = passenger weight used for calculations as
determined in accordance with § 170.090(c)
of this chapter; and
b=distance from the centerline of the vessel
to the geometric center on one side of the
centerline of the passenger deck used to
leave the vessel in case of flooding.

(B) Each passenger occupies 0.25
square meter of deck area; and
(C) All passengers are distributed, on
available deck areas unoccupied by
permanently affixed objects, toward
one side of the vessel on the decks
where passengers would move to escape
from the vessel in case of flooding, so
that they produce the most adverse
heeling moment.
(iii) The heeling moment due to the
launching of survival craft is calculated assuming that—
(A) All survival craft, including
davit-launched liferafts and rescue
boats, fitted on the side to which the
vessel heels after sustained damage,
are swung out if necessary, fully loaded
and ready for lowering;
(B) Persons not in the survival craft
swung out and ready for lowering are
distributed about the centerline of the
vessel so that they do not provide additional heeling or righting moments;
and
(C) Survival craft on the side of the
vessel opposite that to which the vessel
heels remain stowed.
(iv) The heeling moment due to wind
pressure is calculated assuming that—
(A) The wind exerts a pressure of 120
Newtons per square meter;
(B) The wind acts on an area equal to
the projected lateral area of the vessel
above the waterline corresponding to
the intact condition; and
(C) The lever arm of the wind is the
vertical distance from a point at onehalf the mean draft, or the center of
area below the waterline, to the center
of the lateral area.
(5) Each vessel whose arrangements
do not generally allow port or starboard egress may be exempted, by the
Commanding Officer, Marine Safety
Center, from the transverse passenger
heeling moment required by paragraph
(f)(4)(i) of this section. Each vessel exempted must have sufficient longitudinal stability to prevent immersion of
the deck edge during forward or aft
egress.
(6) Each vessel must have an angle of
equilibrium that does not exceed—
(i) 7 degrees for flooding of one compartment;
(ii) 12 degrees for flooding of two
compartments; or

§ 171.080

46 CFR Ch. I (10–1–11 Edition)

(iii) A maximum of 15 degrees for
flooding of one or two compartments
where—
(A) The vessel has positive righting
arms for at least 20 degrees beyond the
angle of equilibrium; and
(B) The vessel has an area under each
righting-arm curve, when the equilibrium angle is between 7 degrees and
15 degrees, in accordance with the formula:
A≥0.0025(q¥1)
where—
A=Area required in m-rad under each righting-arm curve measured from the angle of
equilibrium to the smaller of either the
angle at which downflooding occurs or the
angle of vanishing stability.
q=actual angle of equilibrium in degrees

(7) The margin line of the vessel must
not be submerged when the vessel is in
equilibrium.
(8) Each vessel must have a maximum angle of equilibrium that does
not exceed 15 degrees during intermediate stages of flooding.
(9) Each vessel must have a range of
stability and a maximum righting arm
during each intermediate stage of
flooding as follows:
Required
range
(degrees)

Vessel service
Exposed waters, oceans, or
Great Lakes winter ..............
Partially-protected waters or
Great Lakes summer ...........
Protected waters .....................

Required maximum righting
arm

7

0.05 m

5
5

0.035 m
0.035 m

Only one breach in the hull and only
one free surface need be assumed when
meeting the requirements of this paragraph.

(g) Damage survival for vessels constructed before January 1 2009 authorized
to carry more than 12 passengers on an
international voyage requiring a SOLAS
Passenger Ship Safety Certificate. A vessel is presumed to survive assumed
damage if it is shown by calculations
to comply with the damage stability
required for that vessel by the International Convention for the Safety of
Life at Sea, 1974, as amended, the applicable
regulations
of
IMO
Res.
MSC.216(82) (incorporated by reference,
see § 171.012).
(h) Equalization. (1) Equalization systems on vessels of 150 gross tons or
more in ocean service must meet the
following:
(i) Equalization must be automatic
except that the Commanding Officer,
Marine Safety Center may approve
other means of equalization if—
(A) It is impracticable to make
equalization automatic; and
(B) Controls to cross-flooding equipment are located above the bulkhead
deck.
(ii) Equalization must be fully accomplished within 15 minutes after
damage occurs.
(2) Equalization on vessels under 150
gross tons in ocean service and on all
vessels in other than ocean service
must meet the follmwing:
(i) Equalization must not depend on
the operation of valves.
(ii) Equalization must be fully accomplished within 15 minutes after
damage occurs.
(3) The estimated maximum angle of
heel before equalization must be approved by the Commanding Officer,
Marine Safety Center.

TABLE 171.080(a)—EXTENT AND CHARACTER OF DAMAGE
Vessel
designator 1
Z ..........

Y ..........

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X ..........

Longitudinal penetration 2

Transverse
penetration 3,4

10 feet (3 meters) plus ).03L or 35
feet (10.7 meters) whichever is
less. 5
10 feet (3 meters) plus )0.03L or
35 feet (10.7 meters) whichever
is less.
10 feet (3 meters) plus )0.03L or
35 feet (10.7 meters whichever
is less.
20 feet (6.1 meters) plus 0.04L ....

B/5 ...............

from the baseline upward
without limit.

Assumes no damage to any main
transverse watertight bulkhead.

B/5 ...............

From the baseline upward
without limit.

B/5 ...............

from the baseline upward
without limit.

B/5 ...............

From the top of the double
bottom upward without
limit.

Assumes damage to no
one main transverse
bulkhead.
Assumes damage to no
one main transverse
bulkhead.
Assumes damage to no
one main transverse
bulkhead.

Vertical penetration

Character of Damage

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more than
watertight
more than
watertight
more than
watertight

Coast Guard, DHS

§ 171.085

TABLE 171.080(a)—EXTENT AND CHARACTER OF DAMAGE—Continued
Vessel
designator 1

Longitudinal penetration 2

Transverse
penetration 3,4

W .........

20 feet (6.1 meters) plus 0.04L ....

B/5 ...............

Vertical penetration
From the baseline upward
without limit.

Character of Damage
Assumes damage to at least two
main transverse watertight bulkheads.

(1) W,X,Y, and Z are determined from Table 171.080(b).
(2) L=LBP of the vessel in feet (meters).
(3) B=the beam of the vessel in feet (meters) measured at or below the deepest subdivision load line as defined in 171.010(a)
except that, when doing calculations for a vessel that operates only on inland waters or a ferry vessel, B may be taken as the
mean of the maximum beam on the bulkhead deck and the maximum beam at the deepest subdivision load line.
(4) The transverse penetration is applied inboard from the side of the vessel, at right angles to the centerline, at the level of the
deepest subdivision load line.
(5) .1L or 6 feet (1.8 meters) whichever is greater for vessels described in § 171.070(e)(2).

TABLE 171.080(b)
Vessel designator

Vessel category
Vessels with type I subdivision and a factor of
subdivision as determined from § 171.065
(a) or (b) of 0.33 or less.
Vessels with type I subdivision and a factor of
subdivision as determined from § 171.065
(a) or (b) greater than 0.33 and less than or
equal to 0.50.
Vessels with Type II subdivision that are required to meet a two compartment standard
of flooding.
All other vessels ...............................................

W.

X.

Y.

Z.

TABLE 171.080(c)—PERMEABILITY
Permeability
(percent

Spaces and tanks
Cargo, coal, stores ...........................................
Accommodations ..............................................
Machinery .........................................................
Tanks ................................................................
1 Whichever

60.
95.
85.
o or 95.1

value results in the more disabling condition.

[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988; CGD 89–037, 57 FR 41826, Sept. 11, 1992;
CGD 94–010, 60 FR 53713, Oct. 17, 1995; CGD 97–
057, 62 FR 51049, Sept. 30, 1997; USCG–2007–
29018, 72 FR 53968, Sept. 21, 2007; USCG–2007–
0030, 75 FR 78085, Dec. 14, 2010]

pmangrum on DSK3VPTVN1PROD with CFR

Subpart D—Additional Subdivision
Requirements
§ 171.085 Collision bulkhead.
(a) Paragraphs (b) through (g) of this
section apply to each vessel of 100 gross
tons or more and paragraphs (h)
through (j) of this section apply to
each vessel that is less than 100 gross
tons.
(b) The portion of the collision bulkhead that is below the bulkhead deck
must be watertight.
(c) Each portion of the collision bulkhead must be at least—

(1) 5 percent of the LBP from the forward perpendicular in a motor vessel;
and
(2) 5 feet (1.52 meters) from the forward perpendicular in a steam vessel.
(d) The collision bulkhead must be no
more than 10 feet (3 meters) plus 5 percent of the LBP from the forward perpendicular.
(e) The collision bulkhead must extend to the deck above the bulkhead
deck if the vessel—
(1) Is in ocean service; and
(2) Has a superstructure that extends
from a point forward of the collision
bulkhead to a point at least 15 percent
of the LBP aft of the collision bulkhead.
(f) The collision bulkhead required by
paragraph (e) of this section must have
the following characteristics:
(1) The portion of the collision bulkhead above the bulkhead deck must be
weathertight.
(2) If the portion of the collision
bulkhead above the bulkhead deck is
not located directly above the collision
bulkhead below the bulkhead deck,
then the bulkhead deck between must
be weathertight.
(g) Each opening in the collision
bulkhead must—
(1) Be located above the bulkhead
deck; and
(2) Have a watertight closure.
(h) Each collision bulkhead—
(1) Must extend to the deck above the
bulkhead deck if in ocean service as defined in § 170.050(f) of this chapter or to
the bulkhead deck if in service on
other waters;
(2) May not have watertight doors in
it; and
(3) May have penetrations and openings that—

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§ 171.090

46 CFR Ch. I (10–1–11 Edition)

(i) Are located as high and as far inboard as practicable; and
(ii) Except as provided in paragraph
(i) of this section, have means to make
them watertight.
(i) Each vessel that is not required to
comply with a one or two compartment
standard of flooding may have an opening that cannot be made watertight in
the collision bulkhead below the bulkhead deck if—
(1) The lowest edge of the opening is
not more than 12 inches (30.5 centimeters) below the bulkhead deck; and
(2) There are at least 36 inches (92
centimeters) of intact collision bulkhead below the lower edge of the opening.
(j) Each portion of the collision bulkhead must be—
(1) At least 5 percent of the LBP from
the forward perpendicular; and
(2) No more than 15 percent of the
LBP from the forward perpendicular if
the space forward of the collision bulkhead is not subject to damage stability
requirements and at any location aft of
the location described in paragraph
(j)(1) of this section if the space forward of the collision bulkhead is subject to damage stability requirements.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 945, Jan. 10,
1996]

§ 171.090 Aft peak bulkhead.
(a) Each of the following vessels must
have an aft peak bulkhead:
(1) Each vessel 100 gross tons or more
on an international voyage.
(2) Each other vessel of more than 150
gross tons.
(b) Except as specified in paragraph
(c) of this section, each portion of the
aft peak bulkhead below the bulkhead
deck must be watertight.
(c) A vessel may have an aft peak
bulkhead that does not intersect the
bulkhead deck if approved by the Commanding Officer, Marine Safety Center.

pmangrum on DSK3VPTVN1PROD with CFR

[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988]

§ 171.095 Machinery space bulkhead.
(a) This section applies to each vessel
of 100 gross tons or more.
(b) Except as provided in paragraph
(c) of this section, a vessel required to

have Type I or II subdivision must have
enough main transverse watertight
bulkheads to separate the machinery
space from the remainder of the vessel.
All portions of these bulkheads must
be watertight below the bulkhead deck.
(c) Compliance with paragraph (b) of
this section is not required if the vessel
has sufficient air tanks or other internal buoyancy to maintain the vessel
afloat while in the full load condition
when all compartments and all other
tanks are flooded. If foam is used to
comply with this paragraph, it must be
installed in accordance with the requirements in § 170.245 of this subchapter.
§ 171.100 Shaft
tubes.

tunnels

and

(a) Stern tubes in each of the following vessels must be enclosed in watertight spaces:
(1) Each vessel of 100 gross tons or
more on an international voyage.
(2) Each other vessel over 150 gross
tons in ocean or Great Lakes service.
(3) Each vessel under 100 gross tons
that carries more than 12 passengers on
an international voyage.
(b) The watertight seal in the bulkhead between the stern tube space and
the machinery space must be located in
a watertight shaft tunnel. The vessel
must be designed so that the margin
line will not be submerged when the
watertight shaft tunnel is flooded.
(c) If a vessel has two or more shaft
tunnels, they must be connected by a
watertight passageway.
(d) If a vessel has two or less shaft
tunnels, only one door is permitted between them and the machinery space.
If a vessel has more then two shaft tunnels, only two doors are permitted between them and the machinery space.
§ 171.105

Double bottoms.

(a) This section applies to each vessel
that carries more than 12 passengers on
an international voyage and all other
vessels that are—
(1) 100 gross tons or more; and
(2) In ocean or Great Lakes service.
(b) Each vessel over 165 feet (50 meters) and under 200 feet (61 meters) in
LBP must have a double bottom that
extends from the forward end of the

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Coast Guard, DHS

§ 171.105

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machinery space to the fore peak bulkhead.
(c) Each vessel over 200 feet (61 meters) and under 249 feet (76 meters) in
LBP must have a double bottom that
extends from the fore peak bulkhead to
the forward end of the machinery space
and a double bottom that extends from
the aft peak bulkhead to the aft end of
the machinery space.
(d) Each vessel 249 feet (76 meters) in
LBP and upward must have a double
bottom that extends from the fore to
the aft peak bulkhead.
(e) Each double bottom required by
this section must be at least the depth

at the centerline given by the following
equation:
D=18.0+0.05(L) inches
D=45.7+0.417(L) centimeters
where—
D=the depth at the centerline in inches (centimeters).
L=LBP in feet (meters).

(f) The line formed by the intersection of the margin plate and the bilge
plating must be above the horizontal
plane C, illustrated in Figure 171.105, at
all points. The horizontal plane C is defined by point B, located, as shown in
Figure 171.105, in the midships section.

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46 CFR Ch. I (10–1–11 Edition)

(g) A double bottom is not required
in a tank that is integral with the hull
of a vessel if—
(1) The tank is used exclusively for
the carriage of liquids; and
(2) It is approved by the Commanding
Officer, Marine Safety Center.
(h) A double bottom is not required
in any part of a vessel where the separation of main transverse watertight
bulkheads is governed by a factor of
subdivision less than or equal to 0.50
if—
(1) The Commanding Officer, Marine
Safety Center approves;

(2) The vessel makes short international voyages; and
(3) The vessel is permitted by § 75.10–
10 of this chapter to carry a number of
passengers in excess of the lifeboat capacity.
[CGD 79–023, 48 FR 51017, Nov 4. 1983, as
amended by CGD 88–070, 53 FR 34532, Sept. 7,
1988]

§ 171.106

Wells in double bottoms.

(a) This section applies to each vessel
that has a well installed in a double
bottom required by § 171.105.

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§ 171.106

Coast Guard, DHS

§ 171.112

(b) Except as provided in paragraph
(c) of this section—
(1) The depth of a well must be at
least 18 inches (45.7 cm) less than the
depth of the double bottom at the centerline; and
(2) The well may not extend below
the horizontal plane C illustrated in
Figure 171.105.
(c) A well may extend to the outer
bottom of a double bottom at the after
end of a shaft tunnel.
§ 171.108

Manholes in double bottoms.

(a) The number of manholes in the
inner bottom of a double bottom required by § 171.105 must be reduced to
the minimum required for adequate access.
(b) Each manhole must have a cover
that can be—
(1) Made watertight; and
(2) Protected from damage by cargo
or coal.
§ 171.109 Watertight floors in double
bottoms.
If a vessel is required to have a double bottom, a watertight transverse division must be located in the double
bottom under each main transverse watertight bulkhead or as near as practicable to the main transverse watertight bulkhead. If a vessel also has
duct keels, the transverse divisions
need not extend across them.

Subpart E—Penetrations and
Openings in Watertight Bulkheads
§ 171.110

Specific applicability.

(a) Sections 171.111, 171.112, and
171.113 apply to each vessel of 100 gross
tons or more.
(b) Section 171.114 applies to each
vessel under 100 gross tons.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 945, Jan. 10,
1996; 62 FR 51353, Sept. 30, 1997]

pmangrum on DSK3VPTVN1PROD with CFR

§ 171.111 Penetrations and openings in
watertight bulkheads in vessels of
100 gross tons or more.
(a) Except as provided in paragraph
(f) of this section, each opening in a
watertight bulkhead must have a
means to close it watertight.

(b) Except in a machinery space, the
means for closing each opening may
not be by bolted portable plates.
(c) If a main transverse watertight
bulkhead is penetrated, the penetration must be made watertight. Lead or
other heat sensitive materials must
not be used in a system that penetrates
a main transverse watertight bulkhead
if fire damage to this system would reduce the watertight integrity of the
bulkhead.
(d) A main transverse watertight
bulkhead must not be penetrated by
valves or cocks unless they are a part
of a piping system.
(e) If a pipe, scupper, or electric cable
passes through a main transverse watertight bulkhead, the opening through
which it passes must be watertight.
(f) A main transverse watertight
bulkhead may not have non-watertight
penetrations below the bulkhead deck
unless—
(1) The margin line is more than 9
inches (23 centimeters) below the bulkhead deck at the intersection of the
margin line and the line formed by the
intersection of the plane of the main
transverse watertight bulkhead and
the shell; and
(2) Making all penetrations watertight is impracticable.
(g) Penetrations approved in accordance with paragraph (f) of this section
must comply with the following:
(1) The bottom of the penetration
must not be located—
(i) More than 24 inches (61 centimeters) below the bulkhead deck; nor
(ii) Less than 9 inches (23 centimeters) above the margin line.
(2) The penetration must not be located outboard from the centerline
more than 1⁄4 of the beam of the vessel
measured—
(i) On the bulkhead deck; and
(ii) In the vertical plane of the penetration.
(h) No doors, manholes, or other access openings may be located in a watertight bulkhead that separates two
cargo spaces or a cargo space and a permanent or reserve bunker.
§ 171.112 Watertight door openings.
(a) The opening for a watertight door
must be located as high in the bulkhead and as far inboard as practicable.

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46 CFR Ch. I (10–1–11 Edition)

(b) No more than one door, other
than a door to a bunker or shaft alley,
may be fitted in a main transverse watertight bulkhead within spaces containing the following:
(1) Main and auxiliary propulsion machinery.
(2) Propulsion boilers.
(3) Permanent bunkers.
§ 171.113

Trunks.

(a) For the purpose of this section,
‘‘trunk’’ means a large enclosed passageway through any deck or bulkhead
of a vessel.
(b) Each trunk, other than those
specified in paragraph (c) of this section, must have a watertight door at
each end except that a trunk may have
a watertight door at one end if—
(1) The trunk does not pass through
more than one main compartment;
(2) The sides of the trunk are not
nearer to the shell than is permitted by
§ 171.067(c) for the sides of a recess in a
bulkhead; and
(3) The vessel complies with the subdivision requirements in this part when
the volume of the trunk is included
with the volume of the compartment
into which it opens.
(c) Each trunk that provides access
from a crew accommodation space and
that passes through a main transverse
watertight bulkhead must comply with
the following:
(1) The trunk must be watertight.
(2) The trunk, if used for passage at
sea, must have at least one end above
the margin line and access to the other
end of the trunk must be through a watertight door.
(3) The trunk must not pass through
the first main transverse watertight
bulkhead aft of the collision bulkhead.

pmangrum on DSK3VPTVN1PROD with CFR

§ 171.114 Penetrations and openings in
watertight bulkheads in a vessel
less than a 100 gross tons.
(a) Penetrations and openings in watertight bulkheads must—
(1) Be kept as high and as far inboard
as practicable; and
(2) Have means to make them watertight.
(b) Watertight bulkheads must not
have sluice valves.

(c) Each main traverse watertight
bulkhead must extend to the bulkhead
deck.
[CGD 85–080, 62 FR 51353, Sept. 30, 1997]

Subpart F—Openings in the Side
of a Vessel Below the Bulkhead or Weather Deck
§ 171.115 Specific applicability.
(a) Sections 171.116, 171.117, and
171.118 apply to each vessel of 100 gross
tons or more.
(b) Section 171.119 applies to each
vessel under 100 gross tons.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 945, Jan. 10,
1996; 62 FR 51353, Sept. 30, 1997]

§ 171.116 Port lights.
(a) A vessel may have port lights
below the bulkhead deck if—
(1) It is greater than 150 gross tons;
and
(2) It is in ocean service.
(b) All port lights in a space must be
non-opening if the sill of any port light
in that space is below a line that—
(1) Is drawn parallel to the line
formed by the intersection of the bulkhead deck and the shell of the vessel;
and
(2) Has its lowest point 21⁄2 percent of
the beam of the vessel above the deepest subdivision load line.
(c) For the purpose of paragraph (b)
of this section, the beam of the vessel
is measured at or below the deepest
subdivision load line.
(d) Except as provided in paragraph
(e) of this section, no port light may be
located in a space that is used exclusively for the carriage of cargo, stores,
or coal.
(e) A port light may be located in a
space used alternately for the carriage
of cargo or passengers.
(f) Each port light installed below the
bulkhead deck must conform to the
following requirements:
(1) The design of each port light must
be approved by the Commanding Officer, Marine Safety Center.
(2) Each non-opening port light must
be watertight.
(3) Each opening port light must be
constructed so that it can be secured
watertight.

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Coast Guard, DHS

§ 171.119

(4) Each opening port light must be
installed with at least one bolt that is
secured by a round slotted or recessed
nut that requires a special wrench to
remove. The nut must be protected by
a sleeve or guard to prevent it from
being removed with ordinary tools.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988]

pmangrum on DSK3VPTVN1PROD with CFR

§ 171.117 Dead covers.
(a) Except as provided in paragraph
(b) of this section, each port light with
the sill located below the margin line
must have a hinged, inside dead cover.
(b) The dead cover on a port light located in an accommodation space for
passengers other than steerage passengers may be portable if—
(1) The apparatus for stowing the
dead cover is adjacent to its respective
port light;
(2) The port light is located above the
deck that is immediately above the
deepest subdivision load line;
(3) The port light is aft of a point
one-eighth of the LBP of the vessel
from the forward perpendicular; and
(4) The port light is above a line
that—
(i) Is parallel to the line formed by
the intersection of the bulkhead deck
and the side of the vessel; and
(ii) Has its lowest point at a height of
12 feet (3.66 meters) plus 21⁄2 percent of
the beam of the vessel above the deepest subdivision load line.
(c) For the purpose of paragraph (b)
of this section, the beam of the vessel
is measured at or below the deepest
subdivision load line.
(d) Each dead cover must be designed
so that—
(1) It can be secured watertight; and
(2) It is not necessary to release any
of the special nuts required in
§ 171.116(f)(4) in order to secure the dead
cover.
§ 171.118 Automatic ventilators and
side ports.
(a) An automatic ventilator must not
be fitted in the side of a vessel below
the bulkhead deck unless approved by
the Commanding Officer, Marine Safety Center.
(b) The design and construction of
each gangway, cargo and coaling port,

and similar opening in the side of a
vessel must be approved by the Commanding Officer, Marine Safety Center.
(c) In no case may the lowest point of
any gangway, cargo and coaling port,
or similar opening be below the deepest
subdivision load line.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988]

§ 171.119 Openings below the weather
deck in the side of a vessel less
than 100 gross tons.
(a) If a vessel operates on exposed or
partially protected waters, an opening
port light is not permitted below the
weather deck unless—
(1) The sill is at least 30 inches (76.2
centimeters) above the deepest subdivision load line; and
(2) It has an inside, hinged dead
cover.
(b) Except for engine exhausts, each
inlet or discharge pipe that penetrates
the hull below a line drawn parallel to
and at least 6 inches (15.2 centimeters)
above the deepest subdivision load line
must have means to prevent water
from entering the vessel if the pipe
fractures or otherwise fails.
(c) A positive action valve or cock
that is located as close as possible to
the hull is an acceptable means for
complying with paragraph (b) of this
section.
(d) If an inlet or discharge pipe is inaccessible, the means for complying
with paragraph (b) of this section must
be a shut-off valve that is—
(1) Operable from the weather deck or
other accessible location above the
bulkhead deck; and
(2) Labeled at the operating point for
identity and direction of closing.
(e) Any connecting device or valve in
a hull penetration must not be cast
iron.
(f) Each plug cock in an inlet or discharge pipe must have a means, other
than a cotter pin, to prevent its loosening or removal from the body.
[CGD 85–080, 62 FR 51353, Sept. 30, 1997]

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§ 171.120

46 CFR Ch. I (10–1–11 Edition)

Subpart G—Watertight Integrity
Above the Margin Line
§ 171.120

§ 171.124 Watertight integrity above
the margin line in a vessel less than
100 gross tons.

Specific applicability.

Each vessel that is 100 gross tons or
more must comply with § 171.122 and
each vessel under 100 gross tons must
comply with § 171.124.
[CGD 85–080, 62 FR 51354, Sept. 30, 1997]

§ 171.122 Watertight integrity above
the margin line in a vessel of 100
gross tons or more.

pmangrum on DSK3VPTVN1PROD with CFR

(a) For the purpose of this section, a
partial watertight bulkhead is one in
which all portions are not watertight.
(b) Except as provided in paragraph
(d) of this section, the bulkhead deck
or a deck above it must be weathertight.
(c) Partial watertight bulkheads or
web frames must be located in the immediate vicinity of main transverse
watertight bulkheads to minimize as
much as practicable the entry and
spread of water above the bulkhead
deck.
(d) If a partial watertight bulkhead
or web frame is located on the bulkhead deck in order to comply with
paragraph (c) of this section, the joint
between it and the shell and bulkhead
deck must be watertight.
(e) If a partial watertight bulkhead
does not line up with a main transverse
watertight bulkhead below the bulkhead deck, the bulkhead deck between
them must be watertight.
(f) Each opening in an exposed weather deck must—
(1) Have a coaming that complies
with the height requirements in table
171.124(d); and
(2) Have a means for closing it weathertight.
(g) Each port light located between
the bulkhead deck and the next deck
above the bulkhead deck must have an
inside dead cover than can be secured
watertight.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 945, Jan. 10,
1996; 62 FR 51354, Sept. 30, 1997]

(a) Each hatch exposed to the weather must be watertight; except that, the
following hatches may be weathertight:
(1) Each hatch on a watertight trunk
that extends at least 12 inches (30.5
centimeters) above the weather deck.
(2) Each hatch in a cabin top.
(3) Each hatch on a vessel that operates only on protected waters.
(b) Each hatch cover must—
(1) Have securing devices; and
(2) Be attached to the hatch frame or
coaming by hinges, captive chains, or
to other devices to prevent its loss.
(c) Each hatch that provides access
to crew or passenger accommodations
must be operable from either side.
(d) Except as provided in paragraph
(e) of this section, a weathertight door
with permanent watertight coamings
that comply with the height requirements in table 171.124(d) must be provided for each opening located in a
deck house or companionway that—
(1) Gives access into the hull; and
(2) Is located in—
(i) A cockpit;
(ii) A well; or
(iii) An exposed location on a flush
deck vessel.
TABLE 171.124(d)
Route
Exposed or partially protected
Protected ...............................

Height of coaming
6 inches (15.2 centimeters).
3 inches (7.6 centimeters).

(e) If an opening in a location specified in paragraph (d) of this section is
provided with a Class 1 watertight
door, the height of the watertight coaming need only be sufficient to accommodate the door.
[CGD 85–080, 62 FR 51354, Sept. 30, 1997]

Subpart H—Drainage of Weather
Decks
§ 171.130

Specific applicability.

(a) Section 171.135 applies to each
vessel that is 100 gross tons or more.

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§ 171.150

(b) Sections 171.140, 171.145, 171.150,
and 171.155 apply to each vessel under
100 gross tons.
[CGD 79–023, 48 FR 51017, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 945, Jan. 10,
1996; 62 FR 51354, Sept. 30, 1997]

§ 171.135 Weather deck drainage on a
vessel of 100 gross tons or more.
The weather deck must have freeing
ports, open rails, and scuppers, as necessary, to allow rapid clearing of water
under all weather conditions.
§ 171.140 Drainage of a flush deck vessel.
(a) Except as provided in paragraph
(b) of this section, the weather deck on
a flush deck vessel must be watertight
and have no obstruction to overboard
drainage.
(b) Each vessel with a flush deck may
have solid bulwarks in the forward onethird length of the vessel if—
(1) The bulwarks do not form a well
enclosed on all sides; and
(2) The foredeck of the vessel has sufficient sheer to ensure drainage aft.
[CGD 85–080, 62 FR 51354, Sept. 30, 1997]

pmangrum on DSK3VPTVN1PROD with CFR

§ 171.145 Drainage of a vessel with a
cockpit.
(a) Except as follows, the cockpit
must be watertight:
(1) A cockpit may have companionways if they comply with § 171.124(d).
(2) A cockpit may have ventilation
openings along its inner periphery if—
(i) The vessel operates only on protected or partially protected waters;
(ii) The ventilation openings are located as high as possible in the side of
the cockpit; and
(iii) The height of the ventilation
opening does not exceed 2 inches (5 centimeters).
(b) The cockpit must be designed to
be self-bailing.
(c) Scuppers installed in a cockpit
must be located to allow rapid clearing
of water in all probable conditions of
list and trim.
(d) Scuppers must have a combined
area of at least the area given by either
of the following equations:
A=0.1(D) square inches.
A=6.94(D) square centimeters.
Where—

A = the combined area of the scuppers in
square inches (square centimeters).
D = the area of the cockpit in square feet
(square meters).

(e) The cockpit deck of a vessel that
operates on exposed or partially protected waters must be at least 10
inches (24.5 centimeters) above the
deepest subdivision load line, unless
the vessel complies with—
(1) The intact stability requirements
of § 171.150;
(2) The Type II subdivision requirements in §§ 171.070, 171.072, and 171.073;
and
(3) The damage stability requirements in § 171.080.
(f) The cockpit deck of all vessels
that do not operate on exposed or partially protected waters must be located
as high above the deepest subdivision
load line as practicable.
[CGD 85–080, 62 FR 51354, Sept. 30, 1997]

§ 171.150 Drainage of a vessel with a
well deck.
(a) Each well deck on a vessel must
be watertight.
(b) Except as provided in paragraphs
(c) and (d) of this section, the area required for freeing ports in the bulwarks
that form a well must be determined as
follows:
(1) If a vessel operates on exposed or
partially protected waters, it must
have at least 100 percent of the freeing
port area derived from table 171.150.
(2) If a vessel operates only on protected or partially protected waters
and complies with the requirements in
the following sections for a vessel that
operates on exposed waters, it must
have at least 50 percent of the freeing
port area derived from table 171.150:
(i) The intact stability requirements
of § 171.030 or 171.050 and § 171.170.
(ii) The subdivision requirements of
§ 171.040, 171.043, or 171.070.
(iii) The damage stability requirements of § 171.080.
(3) If a vessel operates only on protected waters, the freeing port area
must be at least equal to the scupper
area required by § 171.145(d) for a cockpit of the same size.
(c) The freeing ports must be located
to allow rapid clearing of water in all
probable conditions of list and trim.

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§ 171.155

46 CFR Ch. I (10–1–11 Edition)

(d) If a vessel that operates on exposed or partially protected waters
does not have free drainage from the
foredeck aft, then the freeing port area
must be derived from table 171.150
using the entire bulwark length rather
than the bulwark length in the after
two-thirds of the vessel as stated in the
table.
TABLE 171.150
Height of solid bulwark in inches (centimeters)

Freeing port
area 1,2

6(15) ..............................................................
12(30) ............................................................
18(46) ............................................................
24(61) ............................................................
30(76) ............................................................
36(91) ............................................................

2(42.3)
4(84.7)
8(169.3)
12(253.9)
16(338.6)
20(423.2)

1 Intermediate values of freeing port area can be obtained
by interpolation.
2 In square inches per foot (square centimeters per meter)
of bulwark length in the after 2⁄3 of the vessel.

[CGD 85–080, 62 FR 51354, Sept. 30, 1997]

§ 171.155

Drainage of an open boat.

The deck within the hull of an open
boat must drain to the bilge. Overboard
drainage of the deck is not permitted.

PART 172—SPECIAL RULES
PERTAINING TO BULK CARGOES

172.010
172.015
172.020
172.030
172.040

Applicability.
Document of authorization.
Incorporation by reference.
Exemptions for certain vessels.
Certificate of loading.

Subpart B—Bulk Grain

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172.080
172.085
172.087
172.090
172.095
172.100
172.103
172.104
172.105
172.110

Specific applicability.
Hull type.
Cargo loading assumptions.
Intact transverse stability.
Intact longitudinal stability.
Watertight integrity.
Damage stability.
Character of damage.
Extent of damage.
Survival conditions.

Subpart F—Special Rules Pertaining to a
Ship That Carries a Hazardous Liquid
Regulated Under Subchapter O of This
Chapter
172.125
172.127
172.130
172.133
172.135
172.140
172.150

Specific applicability.
Definitions.
Calculations.
Character of damage.
Extent of damage.
Permeability of spaces.
Survival conditions.

Subpart H—Special Rules Pertaining to
Great Lakes Dry Bulk Cargo Vessels

Subpart C—Special Rules Pertaining to a
Barge That Carries a Cargo Regulated
Under Subchapter D of This Chapter
172.047
172.048
172.050

Subpart E—Special Rules Pertaining to a
Barge That Carries a Hazardous Liquid
Regulated Under Subchapter O of This
Chapter

172.155 Specific applicability.
172.160 Definitions.
172.165 Intact stability calculations.
172.170 Damage stability calculations.
172.175 Character of damage.
172.180 Extent of damage.
172.185 Permeability of spaces.
172.195 Survival conditions.
172.205 Local damage.

Subpart A—General
Applicability.

Intact stability.

Subpart G—Special Rules Pertaining to a
Ship That Carries a Bulk Liquefied Gas
Regulated Under Subchapter O of This
Chapter

[CGD 85–080, 62 FR 51355, Sept. 30, 1997]

Sec.
172.005

172.070

Specific applicability.
Definitions.
Damage stability.

172.215
172.220
172.225
172.230
172.235
172.240
172.245

Specific applicability.
Definitions.
Calculations.
Character of damage.
Extent of damage.
Permeability of spaces.
Survival conditions.

Subpart D—Special Rules Pertaining to a
Vessel That Carries a Cargo Regulated
Under 33 CFR Part 157

AUTHORITY: 46 U.S.C. 3306, 3703, 5115; E.O.
12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277;
Department of Homeland Security Delegation No. 0170.1.

172.060
172.065

SOURCE: CGD 79–023, 48 FR 51040, Nov. 4,
1983, unless otherwise noted.

Specific applicability.
Damage stability.

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Coast Guard, DHS

§ 172.020

Subpart A—General
§ 172.005

Applicability.

This part applies to each vessel that
carries one of the following cargoes in
bulk:
(a) Grain.
(b) A cargo listed in Table 30.25–1 of
this chapter.
(c) A cargo regulated under 33 CFR
part 157.
(d) A cargo listed in Table 151.01–10(b)
of this chapter.
(e) A cargo listed in Table I of part
153 of this chapter.
(f) A cargo listed in Table 4 of part
154 of this chapter.
(g) Any dry bulk cargo carried in a
new Great Lakes vessel.
[CGD 79–023, 48 FR 51040, Nov. 4, 1983, as
amended by CGD 80–159, 51 FR 33059, Sept. 18,
1986]

Subpart B—Bulk Grain
SOURCE: CGD 95–028, 62 FR 51218, Sept. 30,
1997, unless otherwise noted.

§ 172.010

Applicability.

This subpart applies to each vessel
that loads grain in bulk, except vessels
engaged solely on voyages on rivers,
lakes, bays, and sounds or on voyages
between Great Lake ports and St. Lawrence River ports as far east as a
straight line drawn from Cape de
Rosiers to West Point, Anticosti Island
and as far east of a line drawn along
the 63rd meridian from Anticosti Island
to the north shore of the St. Lawrence
River.

pmangrum on DSK3VPTVN1PROD with CFR

§ 172.015

Document of authorization.

(a) Except as specified in § 172.030,
each vessel that loads grain in bulk
must have a Document of Authorization issued in accordance with one of
the following:
(1) Section 3 of the International
Code for the Safe Carriage of Grain in
Bulk if the Document of Authorization
is issued on or after January 1, 1994. As
used in the Code, the term ‘‘Administration’’ means ‘‘U.S. Coast Guard’’.
(2) Regulation 10 part (a) of the
Annex to IMO Assembly resolution
A.264(VIII) if the Document of Author-

ization was issued before January 1,
1994.
(b) The Commandant recognizes the
National Cargo Bureau, Inc., 17 Battery
Place, Suite 1232, New York, New York
10004–1110, for the purpose of issuing
Documents of Authorization in accordance with paragraph (a)(1) of this section.
[CGD 95–028, 62 FR 51218, Sept. 30, 1997, as
amended by USCG–2007–29018, 72 FR 53968,
Sept. 21, 2007]

§ 172.020

Incorporation by reference.

(a) Certain material is incorporated
by reference into this part with the approval of the Director of the Federal
Register under 5 U.S.C. 552(a) and 1
CFR part 51. To enforce any edition
other than that specified in this section, the Coast Guard must publish a
notice of change in the FEDERAL REGISTER and the material must be available to the public. All approved material is available for inspection at the
National Archives and Records Administration (NARA). For information on
the availability of this material at
NARA, call 202–741–6030 or go to http://
www.archives.gov/federallregister/
codeloflfederallregulations/
ibrllocations.html. It is also available
for inspection at the Coast Guard, Office of Design and Engineering Standards, Naval Architecture Division (CG–
5212), 2100 2nd St., SW., Stop 7126,
Washington, DC 20593–7126, and is available from the sources listed below.
(b) International Maritime Organization (IMO), Publications Section, 4 Albert Embankment, London SE1 7SR,
United Kingdom, +44 (0)20 7735 7611,
http://www.imo.org/.
(1) Amendment to Chapter VI of the
International Convention for the Safety of Life at Sea, 1960, Resolution
A.264(VIII), incorporation by reference
(IBR) approved for § 172.015.
(2) Publication No. 240–E, International Code for the Safe Carriage of
Grain in Bulk, IBR approved for
§ 172.015.
(3) Resolution MEPC.117(52), Amendments to the Annex of the Protocol of
1978 Relating to the International Convention for the Prevention of Pollution
from
Ships,
1973
(IMO
Res.

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§ 172.030

46 CFR Ch. I (10–1–11 Edition)

MEPC.117(52)), Adopted on 15 October
2004, IBR approved for § 172.070.
[USCG–2007–0030, 75 FR 78086, Dec. 14, 2010]

§ 172.030
sels.

Exemptions for certain ves-

(a) Vessels are exempt from 172.015 on
voyages between:
(1) United States ports along the
East Coast as far south as Cape Henry,
VA;
(2) Wilmington, NC and Miami, FL;
(3) United States ports in the Gulf of
Mexico;
(4) Puget Sound ports and Canadian
west coast ports or Columbia River
ports, or both;
(5) San Francisco, Los Angeles, and
San Diego, CA.
(b) Vessels exempt by paragraph (a)
of this section must comply with the
following conditions:
(1) The master is satisfied that the
vessel’s longitudinal strength is not
impaired.
(2) The master ascertains the weather to be encountered on the voyage.
(3) Potential heeling moments are reduced to a minimum by carrying as few
slack holds as possible.
(4) Each slack surface must be leveled.
(5) The transverse metacentric height
(GM), in meters, of the vessel throughout the voyage, after correction for liquid free surface, has been shown by stability calculations to be in excess of
the required GM (GMR), in meters.
(i) The GMR is the sum of the increments of GM (GMI) multiplied by the
correction factor, f and r.
Where:
r=(available freeboard) (beam) of the vessel
and
f=1 if r is > 0.268 or
f=(0.268 r) if r is < 0.268.

(ii) The GMI for each compartment
which has a slack surface of grain, i.e.,
is not trimmed full, is calculated by
the following formula:

pmangrum on DSK3VPTVN1PROD with CFR

GMI=(B3×L×0.0661)(Disp.×SF))
where:
B=breadth of slack grain surface (m
L=Length of compartment (m)
Disp.=Displacement of vessel (tons)
SF=Stowage factor of grain in compartment
(cubic meters/tons)

(c) Vessels which do not have the
Document of Authorization required by
§ 172.015 may carry grain in bulk up to
one third of their deadweight tonnage
provided the stability complies with
the requirements of Section 9 of the
International Code for the Safe Carriage of Grain in Bulk.
§ 172.040

Certificate of loading.

(a) Before it sails, each vessel that
loads grain in bulk, except vessels engaged solely on voyages on the Great
Lakes, rivers, or lakes, bays, and
sounds, must have a certificate of loading issued by an organization recognized by the Commandant for that purpose. The certificate of loading may be
accepted as prima facie evidence of
compliance with the regulations in this
subpart.
(b) The Commandant recognizes the
National Cargo Bureau, Inc., 17 Battery
Place, Suite 1232, New York, New York
10004–1110, for the purpose of issuing
certificates of loading.
[CGD 95–028, 62 FR 51218, Sept. 30, 1997, as
amended by USCG–2007–29018, 72 FR 53968,
Sept. 21, 2007]

Subpart C—Special Rules Pertaining to a Barge That Carries
a Cargo Regulated Under
Subchapter D of This Chapter
§ 172.047

Specific applicability.

This section applies to each tank
barge that carries, in independent
tanks described in § 151.15–1(b) of this
chapter, a cargo listed in Table 30.25–1
of this chapter that is a—
(a) Liquefied flammable gas; or
(b) Flammable liquid that has a Reid
vapor pressure in excess of 25 pounds
per square inch (172.4 KPa).
§ 172.048

Definitions.

As used in this subpart—
MARPOL 73/38 means the International Convention for the Prevention
of Pollution from Ships, 1973, as modified by the Protocol of 1978 relating to
that Convention.
[USCG–2000–7641, 66 FR 55574, Nov. 2, 2001]

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Coast Guard, DHS

pmangrum on DSK3VPTVN1PROD with CFR

§ 172.050

§ 172.065

Damage stability.

(a) Each tank barge is assigned a hull
type number by the Commandant in
accordance with § 32.63–5 of this chapter. The requirements in this section
are specified according to the hull type
number assigned.
(b) Except as provided in paragraph
(c) of this section, each Type I and II
barge hull must have a watertight
weather deck.
(c) If a Type I or II barge hull has an
open hopper, the fully loaded barge
must be shown by design calculations
to have at least 2 inches (50mm) of
positive GM when the hopper space is
flooded to the height of the weather
deck.
(d) When demonstrating compliance
with paragraph (c) of this section, credit may be given for the buoyancy of the
immersed portion of cargo tanks if the
tank securing devices are shown by design calculations to be strong enough
to hold the tanks in place when they
are subjected to the buoyant forces resulting from the water in the hopper.
(e) Each tank barge must be shown
by design calculations to have at least
2 inches (50 mm) of positive GM in each
condition of loading and operation
after assuming the damage specified in
paragraph (f) of this section is applied
in the following locations:
(1) Type I barge hull not in an integrated tow. If a Type I hull is required
and the barge is not a box barge designed for use in an integrated tow, design calculations must show that the
barge hull can survive damage at any
location including on the intersection
of a transverse and longitudinal watertight bulkhead.
(2) Type I barge hull in an integrated
tow. If a Type I hull is required and the
barge is a box barge designed for operation in an integrated tow, design calculations must show that the barge can
survive damage—
(i) To any location on the bottom of
the tank barge except on a transverse
watertight bulkhead; and
(ii) To any location on the side of the
tank barge including on a transverse
watertight bulkhead.
(3) Type II hull. If a Type II hull is required, design calculations must show
that the barge can survive damage to

any location except to a transverse watertight bulkhead.
(f) For the purpose of paragraph (e) of
this section—
(1) Design calculations must include
both side and bottom damage, applied
separately; and
(2) Damage must consist of the most
disabling penetration up to and including penetrations having the following
dimensions:
(i) Side damage must be assumed to
be as follows:
(A) Longitudinal extent—6 feet (183
centimeters).
(B) Transverse extent—30 inches (76
centimeters).
(C) Vertical extent—from the baseline upward without limit.
(ii) Bottom damage must be assumed
to be 15 inches (38.1 centimeters) from
the baseline upward.

Subpart D—Special Rules Pertaining to a Vessel That Carries a Cargo Regulated Under
33 CFR Part 157
§ 172.060 Specific applicability.
This subpart applies to each U.S.
tank vessel that is required to comply
with 33 CFR 157.21.
[CGD 90–051, 57 FR 36246, Aug. 12, 1992]

§ 172.065 Damage stability.
(a) Definitions. As used in this section, Length or L means load line
length (LLL).
(b) Calculations. Each tank vessel
must be shown by design calculations
to meet the survival conditions in
paragraph (g) of this section in each
condition of loading and operation except as specified in paragraph (c) of
this section, assuming the damage
specified in paragraph (d) of this section.
(c) Conditions of loading and operation.
The design calculations required by
paragraph (b) of this section need not
be done for ballast conditions if the
vessel is not carrying oil, other than
oily residues, in cargo tanks.
(d) Character of damage. (1) If a tank
vessel is longer than 738 feet (225
metes) in length, design calculations
must show that it can survive damage
at any location.

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§ 172.065

46 CFR Ch. I (10–1–11 Edition)

(2) If a tank vessel is longer than 492
feet (150 meters) in length, but not
longer than 738 feet (225 meters), design
calculations must show that it can survive damage at any location except the
transverse bulkheads bounding an aft
machinery space. The machinery space
is calculated as a single floodable compartment.
(3) If a tank vessel is 492 feet (150 meters) or less in length, design calculations must show that it can survive
damage—
(i) At any location between adjacent
main transverse watertight bulkheads
except to an aft machinery space;
(ii) To a main transverse watertight
bulkhead spaced closer than the longitudinal extent of collision penetration
specified in Table 172.065(a) from another main transverse watertight bulkhead; and
(iii) To a main transverse watertight
bulkhead or a transverse watertight
bulkhead bounding a side tank or double bottom tank if there is a step or a
recess in the transverse bulkhead that
is longer than 10 feet (3.05 meters) and
that is located within the extent of
penetration of assumed damage. The
step formed by the after peak bulkhead
and after peak tank top is not a step
for the purpose of this regulaton.
(e) Extent of damage. For the purpose
of paragraph (b) of this section—
(1) Design calculations must include
both side and bottom damage, applied
separately; and
(2) Damage must consist of the penetrations having the dimensions given
in Table 172.065(a) except that, if the
most disabling penetrations would be
less than the penetrations described in
this paragraph, the smaller penetration
must be assumed.
(f) Permeability of spaces. When doing
the calculations required in paragraph
(b) of this section—
(1) The permeability of a floodable
space, other than a machinery space,
must be as listed in Table 172.065(b);
(2) Calculations in which a machinery space is treated as a floodable
space must be based on an assumed machinery space permeability of 85%, unless the use of an assumed permeability
of less than 85% is justified in detail;
and

(3) If a cargo tank would be penetrated under the assumed damage, the
cargo tank must be assumed to lose all
cargo and refill with salt water, or
fresh water if the vessel operates solely
on the Great Lakes, up to the level of
the tank vessel’s final equilibrium waterline.
(g) Survival conditions. A vessel is presumed to survive assumed damage if it
meets the following conditions in the
final stage of flooding:
(1) Final waterline. The final waterline, in the final condition of sinkage,
heel, and trim, must be below the lower
edge of an opening through which progressive flooding may take place, such
as an air pipe, or an opening that is
closed by means of a weathertight door
or hatch cover. This opening does not
include an opening closed by a—
(i) Watertight manhole cover;
(ii) Flush scuttle;
(iii) Small watertight cargo tank
hatch cover that maintains the high
integrity of the deck;
(iv) Class 1 door in a watertight bulkhead within the superstructure;
(v) Remotely operated sliding watertight door; or
(vi) Side scuttle of the non-opening
type.
(2) Heel angle. The maximum angle of
heel must not exceed 25 degrees, except
that this angle may be increased to 30
degrees if no deck edge immersion occurs.
(3) Range of stability. Through an
angle of 20 degrees beyond its position
of equilibrium after flooding, a tank
vessel must meet the following conditions:
(i) The righting arm curve must be
positive.
(ii) The maximum righting arm must
be at least 3.94 inches (10 cm).
(iii) Each submerged opening must be
weathertight.
(4) Progressive flooding. Pipes, ducts or
tunnels within the assumed extent of
damage must be either—
(i) Equipped with arrangements such
as stop check valves to prevent progressive flooding to other spaces with
which they connect; or
(ii) Assumed in the design calculations required in paragraph (b) of this
section to permit progressive flooding
to the spaces with which they connect.

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§ 172.090

(h) Buoyancy of superstructure. For
the purpose of paragraph (b) of this section, the buoyancy of any superstructure directly above the side damage is to be disregarded. The unflooded
parts of superstructures beyond the extent of damage may be taken into consideration if they are separated from
the damaged space by watertight bulkheads and no progressive flooding of
these intact spaces takes place.
COLLISION PENETRATION
Longitudinal extent .......... 0.495L2/3 or 47.6 feet ((1⁄3)L2/3 or
14.5m) whichever is shorter.
Transverse extent 1 ......... B/5 or 37.74 feet (11.5m) which
is shorter.
Vertical extent ................. From the baseline upward without limit.
GROUNDING PENETRATION AT THE FORWARD END BUT EXCLUDING ANY DAMAGE AFT OF A POINT 0.3L AFT OF THE FORWARD
PERPENDICULAR
Longitudinal extent ..........

0.495L
or 47.6 feet (( ⁄
or
14.5m) whichever is shorter.
B/6 or 32.81 feet (10m) whichever is shorter but not less
than 16.41 feet (5m).
Vertical extent from the
B/15 or 19.7 feet (6m) whichever
baseline.
is shorter.
GROUNDING PENETRATION AT ANY OTHER LONGITUDINAL
POSITION
)L2/3

13

Transverse extent ...........

Longitudinal extent ..........

L/10 or 16.41 feet (5m) whichever is shorter.
Transverse extent ........... 16.41 feet (5m).
B/15 or 19.7 feet (6m) whichever
Vertical extent from the
baseline.
is shorter.
GROUNDING PENETRATION FOR RAKING DAMAGE
For tank vessels of
20,000 DWT and
above, the following assumed bottom raking
damage must supplement the damage assumptions:.
Longitudinal extent .......... For vessels of 75,000 DWT and
above, 0.6L measured from the
forward perpendicular.
..................................... For vessels of less than 75,000
DWT, 0.4L measured from the
forward perpendicular.
Transverse extent ........... B/3 anywhere in the bottom.
Vertical extent ................. Breach of the outer hull.
1 Damage applied inboard from the vessel’s side at right angles to the centerline at the level of the summer load line assigned under Subchapter E of this chapter.

TABLE 172.065(b)—PERMEABILITY
Permeability
(percent)

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Spaces and tanks
Storeroom spaces ............................................
Accommodation spaces ...................................
Voids .................................................................
Consumable liquid tanks ..................................
Other liquid tanks .............................................

§ 172.070

Intact stability.

All tank vessels of 5,000 deadweight
tons (DWT) and above, contracted after
December 3, 2001, must comply with
the intact stability requirements of
IMO Res. MEPC.117(52) (incorporated
by reference, see § 172.020).
[USCG–2007–0030, 75 FR 78086, Dec. 14, 2010]

TABLE 172.065(a)—EXTENT OF DAMAGE

2/3

[CGD 79–023, 48 FR 51040, Nov. 4, 1983, as
amended by USCG–2000–7641, 66 FR 55574,
Nov. 2, 2001]

60.
95.
95.
95 or 0.1
95 or 0.2

1 Whichever results in the more disabling condition.
2 If tanks are partially filled, the permeability must be determined from the actual density and amount of liquid carried.

Subpart E—Special Rules Pertaining to a Barge That Carries
a Hazardous Liquid Regulated
Under Subchapter O of This
Chapter
§ 172.080

Specific applicability.

This subpart applies to each tank
barge that carries a cargo listed in
Table 151.05 of this chapter.
[CGD 79–023, 48 FR 51040, Nov. 4, 1983, as
amended by USCG–2009–0702, 74 FR 49239,
Sept. 25, 2009]

§ 172.085

Hull type.

If a cargo listed in Table 151.05 of
part 151 of this chapter is to be carried,
the tank barge must be at least the
hull type specified in Table 151.05 of
this chapter for that cargo.
§ 172.087

Cargo loading assumptions.

(a) The calculations required in this
subpart must be done for cargo weights
and densities up to and including the
maximum that is to be endorsed on the
Certificate of Inspection in accordance
with § 151.04–1(c) of this chapter.
(b) For each condition of loading and
operation, each cargo tank must be assumed to have its maximum free surface.
§ 172.090

Intact transverse stability.

(a) Except as provided in paragraph
(b) of this section, each tank barge
must be shown by design calculations
to have a righting arm curve with the
following characteristics:
(1) If the tank barge is in river service, the area under the righting arm
curve must be at least 5 foot-degrees
(1.52 meter-degrees) up to the smallest
of the following angles:

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§ 172.095

46 CFR Ch. I (10–1–11 Edition)

(K)(B)
fe

where—
K=0.3 for river service.
K=0.4 for lakes, bays and sounds and Great
Lakes summer service.
K=0.5 for ocean and Great Lakes winter service.
B=beam in feet (meters).
fe=effective freeboard in feet (meters).

(c) The effective freeboard is given
by—

pmangrum on DSK3VPTVN1PROD with CFR

fe=f + fa ; or
fe=d, whichever is less.

§ 172.095

GM =

0.02(L)

2

d
where—
L=LOA in feet (meters)
d=draft in feet (meters).

§ 172.100

Watertight integrity.

(a) Except as provided in paragraph
(b) of this section, each Type I or II
hopper barge hull must have a weathertight weather deck.
(b) If a Type I or II barge hull has an
open hopper, the fully loaded barge
must be shown by design calculations
to have at least 2 inches (50 mm) of
positive GM when the hopper space is
flooded to the height of the weather
deck.
(c) When doing the calculations required by this section, credit may be
given for the buoyancy of the immersed portion of cargo tanks if the
tank securing devices are shown by design calculations to be strong enough
to hold the tanks in place when they
are subjected to the buoyant forces resulting from the water in the hopper.
§ 172.103

where—
f=the freeboard to the deck edge amidships
in feet (meters).
fa=(1.25)(a/L)((2b/B)–1)(h); or
fa=h, whichever is less.
where—
a=trunk length in feet (meters).
L=LOA in feet (meters)
b=breadth of a watertight trunk in feet (meters).
B=beam of the barge in feet (meters).
h=height of a watertight trunk in feet (meters).
d=draft of the barge in feet (meters).

Intact longitudinal stability.

Each tank barge must be shown by
design calculations to have a longitudinal metacentric height (GM) in feet
(meters) in each condition of loading
and operation, at least equal to the following:

Damage stability.

Each tank barge must be shown by
design calculations to meet the survival conditions in § 172.110 assuming
the damage specified in § 172.104 to the
hull type specified in Table 151.05 of
part 151 of this chapter.
§ 172.104

Character of damage.

(a) Type I barge hull not in an integrated tow. If a Type I hull is required
and the barge is not a box barge designed for use in an integrated tow, design calculations must show that the

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EC01MR91.026

GM =

(d) For the purpose of this section,
downflooding angle means the static
angle from the intersection of the vessel’s centerline and waterline in calm
water to the first opening that does not
close watertight automatically.

EC01MR91.025

(i) The angle of maximum righting
arm.
(ii) The downflooding angle.
(2) If the tank barge is in lakes, bays
and sounds or Great Lakes summer
service, the area under the righting
arm curve must be at least 10 foot-degrees (3.05 meter-degrees) up to the
smallest of the following angles:
(i) The angle of maximum righting
arm.
(ii) The downflooding angle.
(3) If the tank barge is in ocean or
Great Lakes winter service, the area
under the righting arm curve must be
at least 15 foot-degrees (4.57 meter-degrees) up to the smallest of the following angles:
(i) The angle of maximum righting
arm.
(ii) The downflooding angle.
(b) If the vertical center of gravity of
the cargo is below the weather deck at
the side of the tank barge amidships, it
must be shown by design calculations
that the barge has at least the following metacentric height (GM) in feet
(meters) in each condition of loading
and operation:

Coast Guard, DHS

§ 172.127

barge can survive damage at any location including the intersection of a
transverse and a longitudinal bulkhead.
(b) Type I barge hull in an integrated
tow. If a Type I barge hull is required
and the barge is a box barge designed
for operation in an integrated tow, design calculations must show that the
barge can survive damage—
(1) At any location on the bottom of
the tank barge except on a transverse
watertight bulkhead; and
(2) At any location on the side of the
tank barge including on a transverse
watertight bulkhead.
(c) Type II barge hull. If a Type II hull
is required, design calculations must
show that a barge can survive damage
at any location except on a transverse
watertight bulkhead.

pmangrum on DSK3VPTVN1PROD with CFR

§ 172.105 Extent of damage.
For the purpose of § 172.103, design
calculations must include both side
and bottom damage, applied separately. Damage must consist of the
most disabling penetration up to and
including penetrations having the following dimensions:
(a) Side damage must be assumed to
be as follows:
(1) Longitudinal extent—6 feet (183
centimeters).
(2) Transverse extent—30 inches (76
centimeters).
(3) Vertical extent—from the baseline
upward without limit.
(b) Bottom damage must be assumed
to be 15 inches (38 centimeters) from
the baseline upward.
§ 172.110 Survival conditions.
(a) Paragraphs (c) and (d) of this section apply to a hopper barge and paragraphs (e) through (i) apply to all other
tank barges.
(b) A barge is presumed to survive assumed damage if it meets the following
conditions in the final stage of flooding:
(c) A hopper barge must not heel or
trim beyond the angle at which—
(1) The deck edge is first submerged;
or
(2) If the barge has a coaming that is
at least 36 inches (91.5 centimeters) in
height, the intersection of the deck and
the coaming is first submerged, except

as provided in paragraph (d) of this section.
(d) A hopper barge must not heel beyond the angle at which the deck edge
is first submerged by more than ‘‘fa’’
as defined in § 172.090(c).
(e) Except as provided in paragraphs
(h) and (i) of this section, each tank
barge must not heel beyond the angle
at which—
(1) The deck edge is first submerged;
or
(2) If the barge has one or more watertight trunks, the deck edge is first
submerged by more than ‘‘fa’’ as defined in § 172.090(c).
(f) Except as provided in paragraphs
(h) and (i) of this section, a tank barge
must not trim beyond the angle at
which—
(1) The deck edge is first submerged;
or
(2) If the barge has one or more watertight trunks, the intersection of the
deck and the trunk is first submerged.
(g) If a tank barge experiences simultaneous heel and trim, the trim requirements in paragraph (f) of this section apply only at the centerline.
(h) Except as provided in paragraph
(i) of this section, in no case may any
part of the actual cargo tank top be
underwater in the final condition of
equilibrium.
(i) If a barge has a ‘‘step-down’’ in
hull depth on either or both ends and
all cargo tank openings are located on
the higher deck level, the deck edge
and tank top in the stepped-down area
may be submerged.

Subpart F—Special Rules Pertaining to a Ship That Carries
a Hazardous Liquid Regulated
Under Subchapter O of This
Chapter
§ 172.125

Specific applicability.

This subpart applies to each tankship
that carries a cargo listed in Table I of
part 153 of this chapter, except that it
does not apply to a tankship whose
cargo tanks are clean and gas free.
§ 172.127

Definitions.

Length or L means load line length
(LLL).

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§ 172.130

46 CFR Ch. I (10–1–11 Edition)

§ 172.130 Calculations.
(a) Except as provided in § 153.7 of
this chapter, each tankship must be
shown by design calculations to meet
the survival conditions in § 172.150 in
each condition of loading and operation
assuming the damage specified in
§ 172.133 for the hull type prescribed in
part 153 of this chapter.
(b) If a cargo listed in Table I of part
153 of this chapter is to be carried, the
vessel must be at least the hull type
specified in part 153 of this chapter for
that cargo.
[CGD 79–023, 48 FR 51040, Nov. 4, 1983, as
amended by CGD 81–101, 52 FR 7799, Mar. 12,
1987]

pmangrum on DSK3VPTVN1PROD with CFR

§ 172.133 Character of damage.
(a) If a type I hull is required, design
calculations must show that the vessel
can survive damage at any location.
(b) Except as provided in § 153.7 of
this chapter, if a type II hull is required, design calculations must show
that a vessel—
(1) Longer than 492 feet (150 meters)
in length can survive damage at any location; and
(2) Except as specified in paragraph
(d) of this section, 492 feet (150 meters)
or less in length can survive damage at
any location.
(c) If a Type III hull is required, design calculations must show that a vessel—
(1) Except as specified in paragraph
(d) of this section, 410 feet (125 meters)
in length or longer can survive damage
at any location; and
(2) Less than 410 feet (125 meters) in
length can survive damage at any location except to an aft machinery space.
(d) A vessel described in paragraph
(b)(2) or (c)(1) of this section need not
be designed to survive damage to a
main transverse watertight bulkhead
bounding an aft machinery space. Except as provided in § 153.7 of this chapter, the machinery space must be calculated as a single floodable compartment.
[CGD 79–023, 48 FR 51040, Nov. 4, 1983, as
amended by CGD 81–101, 52 FR 7799, Mar. 12,
1987]

§ 172.135 Extent of damage.
For the purpose of § 172.133—

(a) Design calculations must include
both side and bottom damage, applied
separately; and
(b) Damage must consist of the penetrations having the dimensions given
in Table 172.135 except that, if the most
disabling penetrations would be less
than the penetrations given in Table
172.135, the smaller penetration must
be assumed.
TABLE 172.135—EXTENT OF DAMAGE
COLLISION PENETRATION
Longitudinal extent .......... 0.495L 2⁄3 or 47.6 feet ((1⁄3)L 2⁄3 or
14.5m) whichever is shorter.
Transverse extent 1 ......... B/5 or 37.74 feet (11.5m) 2 whichever is shorter.
Vertical extent ................. From the baseline upward without limit.
GROUNDING PENETRATION AT THE FORWARD END BUT EXCLUDING ANY DAMAGE AFT OF A POINT 0.3L AFT OF THE FORWARD
PERPENDICULAR
Longitudinal extent ..........
Transverse extent ...........
Vertical extent from the
baseline upward.

L/10.
B/6 or 32.81 feet (10m) whichever is shorter.
B/15 or 19.7 feet (6m) whichever
is shorter.

GROUNDING PENETRATION AT ANY OTHER LONGITUDINAL
POSITION
Longitudinal extent ..........

L/10 or 16.41 feet (5m) whichever is shorter.
Transverse extent ........... 16.41 feet (5m).
Vertical extent from the
B/15 or 19.7 feet (6m) whichever
baseline upward.
is shorter.
1 Damage applied inboard from the vessel’s side at right angles to the centerline at the level of the summer load line assigned under Subchapter E of this chapter.
2 B is measured amidships.

§ 172.140

Permeability of spaces.

(a) When doing the calculations required in § 172.130, the permeability of a
floodable space other than a machinery
space must be as listed in Table
172.060(b).
(b) Calculations in which a machinery space is treated as a floodable
space must be based on an assumed machinery space permeability of 0.85, unless the use of an assumed permeability
of less than 0.85 is justified in detail.
(c) If a cargo tank would be penetrated under the assumed damage, the
cargo tank must be assumed to lose all
cargo and refill with salt water up to
the level of the tankship’s final equilibrium waterline.
§ 172.150

Survival conditions.

A tankship is presumed to survive assumed damage if it meets the following
conditions in the final stage of flooding:

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Coast Guard, DHS

§ 172.165

(a) Final waterline. The final waterline, in the final condition of sinkage,
heel, and trim, must be below the lower
edge of openings such as air pipes and
openings closed by weathertight doors
or hatch covers. The following types of
openings may be submerged when the
tankship is at the final waterline:
(1) Openings covered by watertight
manhole covers or watertight flush
scuttles.
(2) Small watertight cargo tank
hatch covers.
(3) A Class 1 door in a watertight
bulkhead within the superstructure.
(4) Remotely operated sliding watertight doors.
(5) Side scuttles of the non-opening
type.
(b) Heel angle. (1) Except as described
in paragraph (b)(2) of this section, the
maximum angle of heel must not exceed 15 degrees (17 degrees if no part of
the freeboard deck is immersed).
(2) The Commanding Officer, Marine
Safety Center will consider on a case
by case basis each vessel 492 feet (150
meters) or less in length having a final
heel angle greater than 17 degrees but
less than 25 degrees.
(c) Range of stability. Through an
angle of 20 degrees beyond its position
of equilibrium after flooding, a tankship must meet the following conditions:
(1) The righting arm curve must be
positive.
(2) The maximum righting arm must
be at least 3.95 inches (10 cm).
(3) Each submerged opening must be
weathertight.
(d) Progressive flooding. Pipes, ducts
or tunnels within the assumed extent
of damage must be either—
(1) Equipped with arrangements such
as stop check valves to prevent progressive flooding to other spaces with
which they connect; or
(2) Assumed in the design calculations required by § 172.130 to flood the
spaces with which they connect.
(e) Buoyancy of superstructure. The
buoyancy of any superstructure directly above the side damage is to be
disregarded. The unflooded parts of superstructures beyond the extent of
damage may be taken into consideration if they are separated from the
damaged space by watertight bulk-

heads and no progressive flooding of
these intact spaces takes place.
(f) Metacentric height. After flooding,
the tankship’s metacentric height
must be at least 2 inches (50mm) when
the ship is in the upright position.
(g) Equalization arrangements. Flooding equalization arrangements requiring mechanical operation such as
valves or cross-flooding lines may not
be assumed to reduce the angle of heel.
Spaces joined by ducts of large cross
sectional area are treated as common
spaces.
(h) Intermediate stages of flooding. If
an intermediate stage of flooding is
more critical than the final stage, the
tankship must be shown by design calculations to meet the requirements in
this section in the intermediate stage.
[CGD 79–023, 48 FR 51040, Nov. 4, 1983, as
amended by CGD 88–070, 53 FR 34537, Sept. 7,
1988]

Subpart G—Special Rules Pertaining to a Ship That Carries
a Bulk Liquefied Gas Regulated Under Subchapter O of
This Chapter
§ 172.155

Specific applicability.

This subpart applies to each tankship
that has on board a bulk liquefied gas
listed in Table 4 of part 154 of this
chapter as cargo, cargo residue, or
vapor.
§ 172.160

Definitions.

As used in this subpart—
(a) Length or L means the load line
length (LLL).
(b) MARVS means the Maximum Allowable Relief Valve Setting of a cargo
tank.
§ 172.165

Intact stability calculations.

(a) Design calculations must show
that 2 inches (50mm) of positive
metacentric height can be maintained
by each tankship when it is being loaded and unloaded.
(b) For the purpose of demonstrating
compliance with the requirements of
paragraph (a) of this section, the effects of the addition of water ballast
may be considered.

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pmangrum on DSK3VPTVN1PROD with CFR

§ 172.170

46 CFR Ch. I (10–1–11 Edition)

§ 172.170 Damage
stability
calculations.
(a) Each tankship must be shown by
design calculations to meet the survival conditions in § 172.195 in each condition of loading and operation assuming the damage specified in § 172.175 for
the hull type specified in Table 4 of
part 154 of this chapter.
(b) If a cargo listed in Table 4 of part
154 of this chapter is to be carried, the
vessel must be at least the ship type
specified in Table 4 of part 154 of this
chapter for the cargo.

(f) If a main transverse watertight
bulkhead or transverse watertight
bulkhead bounding a side tank or double bottom tank has a step or a recess
that is longer than 10 feet (3.05 meters)
located within the extent of penetration of assumed damage, the vessel
must be shown by design calculations
to survive damage to this bulkhead.
The step formed by the after peak
bulkhead and after peak tank top is
not a step for the purpose of this regulation.

§ 172.175 Character of damage.
(a) If a type IG hull is required, design calculations must show that the
vessel can survive damage at any location.
(b) If a type IIG hull is required, design calculations must show that a vessel—
(1) Longer than 492 feet (150 meters)
in length can survive damage at any location; and
(2) 492 feet (150 meters) or less in
length can survive damage at any location except the transverse bulkheads
bounding an aft machinery space. The
machinery space is calculated as a single floodable compartment.
(c) If a vessel has independent tanks
type C with a MARVS of 100 psi (689
kPa) gauge or greater, is 492 feet (150
meters) or less in length, and Table 4 of
part 154 of this chapter allows a type
IIPG hull, design calculations must
show that the vessel can survive damage at any location, except as prescribed in paragraph (e) of this section.
(d) If a type IIIG hull is required, except as specified in paragraph (e) of
this section, design calculations must
show that a vessel—
(1) 410 feet (125 meters) in length or
longer can survive damage at any location; and
(2) Less than 410 feet (125 meters) in
length can survive damage at any location, except in the main machinery
space.
(e) The calculations in paragraphs (c)
and (d) of this section need not assume
damage to a transverse bulkhead unless it is spaced closer than the longitudinal extent of collision penetration
specified in Table 172.180 from another
transverse bulkhead.

For the purpose of § 172.170—
(a) Design calculations must include
both side and bottom damage, applied
separately; and
(b) Damage must consist of the penetrations having the dimensions given
in Table 172.180 except that, if the most
disabling penetrations would be less
than the penetrations given in Table
172.180, the smaller penetration must
be assumed.

§ 172.180

Extent of damage.

TABLE 172.180—EXTENT OF DAMAGE
COLLISION PENETRATION
Longitudinal extent ..........
Transverse

extent 1

.........

Vertical extent .................

0.495L2/3 or 47.6 feet ((1/3)L2/3 or
14.5m) whichever is shorter.
B/5 or 37.74 feet (11.5m) 2 whichever is shorter.
From the baseline upward without limit.

GROUNDING PENETRATION AT THE FORWARD END BUT EXCLUDING ANY DAMAGE AFT OF A POINT 0.3L AFT OF THE FORWARD
PERPENDICULAR
Longitudinal extent ..........
Transverse extent ...........
Vertical extent from the
molded line of the shell
at the centerline.

0.495L2/3 or 47.6 feet ((1/3)L2/3 or
14.5m) whichever is shorter.
B/6 or 32.81 feet (10m) whichever is shorter.
B/15 or 6.6 feet (2m) whichever
is shorter.

GROUNDING PENETRATION AT ANY OTHER LONGITUDINAL
POSITION
Longitudinal extent ..........
Transverse extent ...........

L/10 or 16.41 feet (5m) whichever is shorter.
B/6 or 16.41 feet (5m) whichever
is shorter.
B/15 or 6.6 feet (2m) whichever
is shorter.

Vertical extent from the
molded line of the shell
at the centerline.
1 Damage applied inboard from the vessel’s side at right angles to the centerline at the level of the summer load line assigned under Subchapter E of this chapter.
2 B is measured amidships.

§ 172.185

Permeability of spaces.

(a) When doing the calculations required in § 172.170, the permeability of a
floodable space other than a machinery

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Coast Guard, DHS

§ 172.205

space must be as listed in Table
172.060(b).
(b) Calculations in which a machinery space is treated as a floodable
space must be based on an assumed machinery space permeability of 85%, unless the use of an assumed permeability
of less than 85% is justified in detail.
(c) If a cargo tank would be penetrated under the assumed damage, the
cargo tank must be assumed to lose all
cargo and refill with salt water up to
the level of the tankship’s final equilibrium waterline.

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§ 172.195

Survival conditions.

A vessel is presumed to survive assumed damage if it meets the following
conditions in the final stage of flooding:
(a) Final waterline. The final waterline, in the final condition of sinkage,
heel, and trim, must be below the lower
edge of an opening through which progressive flooding may take place, such
as an air pipe, or an opening that is
closed by means of a weathertight door
or hatch cover. This opening does not
include an opening closed by a—
(1) Watertight manhole cover;
(2) Flush scuttle;
(3) Small watertight cargo tank
hatch cover that maintains the high
integrity of the deck;
(4) A Class 1 door in a watertight
bulkhead within the superstructure;
(5) Remotely operated sliding watertight door; or
(6) A side scuttle of the non-opening
type.
(b) Heel angle. The maximum angle of
heel must not exceed 30 degrees.
(c) Range of stability. Through an
angle of 20 degrees beyond its position
of equilibrium after flooding, a tankship must meet the following conditions:
(1) The righting arm curve must be
positive.
(2) The maximum righting arm must
be at least 3.94 inches (10 cm).
(3) Each submerged opening must be
weathertight.
(d) Progressive flooding. If pipes,
ducts, or tunnels are within the assumed extent of damage, arrangements
must be made to prevent progressive
flooding to a space that is not assumed

to be flooded in the damaged stability
calculations.
(e) Buoyancy of superstructure. The
buoyancy of any superstructure directly above the side damage is to be
disregarded. The unflooded parts of superstructures beyond the extent of
damage may be taken into consideration if they are separated from the
damaged space by watertight bulkheads and no progressive flooding of
these intact spaces takes place.
(f) Metacentric height. After flooding,
the tank ship’s metacentric height
must be at least 2 inches (50 mm) when
the vessel is in the upright position.
(g) Equalization arrangements. Equalization arrangements requiring mechanical aids such as valves or cross-flooding lines may not be considered for reducing the angle of heel. Spaces joined
by ducts of large cross-sectional area
are treated as common spaces.
(h) Intermediate stages of flooding. If
an intermediate stage of flooding is
more critical than the final stage, the
tank vessel must be shown by design
calculations to meet the requirements
in this section in the intermediate
stage.
§ 172.205

Local damage.

(a) Each tankship must be shown by
design calculations to meet the survival conditions in paragraph (b) of
this section in each condition of loading and operation assuming that local
damage extending 30 inches (76 cm)
normal to the hull shell is applied at
any location in the cargo length:
(b) The vessel is presumed to survive
assumed local damage if it does not
heel beyond the smaller of the following angles in the final stage of
flooding:
(1) 30 degrees.
(2) The angle at which restoration of
propulsion and steering, and use of the
ballast system is precluded.

Subpart H—Special Rules Pertaining to Great Lakes Dry
Bulk Cargo Vessels
SOURCE: CGD 80–159, 51 FR 33059, Sept. 18,
1986, unless otherwise noted.

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§ 172.215

46 CFR Ch. I (10–1–11 Edition)

§ 172.215 Specific applicability.
This subpart applies to each new
Great Lakes vessel of 1600 gross tons or
more carrying dry cargo in bulk.
§ 172.220 Definitions.
(a) As used in this subpart Length (L),
Breadth (B), and Molded Depth (D) are
as defined in § 45.3 of this chapter.
(b) As used in this part new Great
Lakes Vessel means a vessel operating
solely within the limits of the Great
Lakes as defined in this subchapter
that:
(1) Was contracted for on or after November 17, 1986, or delivered on or after
November 17, 1988.
(2) Has undergone a major conversion
under a contract made on or after November 17, 1986, or completed a major
conversion on or after November 17,
1987.

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[CGD 80–159, 51 FR 33059, Sept. 18, 1986]

§ 172.225 Calculations.
(a) Each vessel must be shown by design calculations to meet the survival
conditions in § 172.245 in each condition
of loading and operation, assuming the
damage specified in § 172.230.
(b) When doing the calculations required by paragraph (a) of this section,
the virtual increase in the vertical center of gravity due to a liquid in a space
must be determined by calculating either—
(1) The free surface effect of the liquid with the vessel assumed heeled five
degrees from the vertical; or
(2) The shift of the center of gravity
of the liquid by the moment of transference method.
(c) In calculating the free surface effect of consumable liquids, it must be
assumed that, for each type of liquid,
at least one transverse pair of wing
tanks or a single centerline tank has a
free surface. The tank or combination
of tanks selected must be those having
the greatest free surface effect.
(d) When doing the calculations required by paragraph (a) of this section,
the buoyancy of any superstructure directly above the side damage must not
be considered. The unflooded parts of
superstructures beyond the extent of
damage may be considered if they are
separated from the damaged space by

watertight bulkheads and no progressive flooding of these intact spaces
takes place.
§ 172.230 Character of damage.
(a) Design calculations must show
that each vessel can survive damage—
(1) To any location between adjacent
main transverse watertight bulkheads;
(2) To any location between a main
transverse bulkhead and a partial
transverse bulkhead in way of a side
wing tank;
(3) To a main or wing tank transverse
watertight bulkhead spaced closer than
the longitudinal extent of collision
penetration specified in Table 172.235 to
another main transverse watertight
bulkhead; and
(4) To a main transverse watertight
bulkhead or a transverse watertight
bulkhead bounding a side tank or double bottom tank if there is a step or a
recess in the transverse bulkhead that
is longer than 10 feet (3.05 meters) and
that is located within the extent of
penetration of assumed damage. The
step formed by the after peak bulkhead
and after peak tank top is not a step
for the purpose of this paragraph.
§ 172.235 Extent of damage.
For the purpose of the calculations
required in § 172.225—
(a) Design calculations must include
both side and bottom damage, applied
separately; and
(b) Damage must consist of the penetrations having the dimensions given
in Table 172.235 except that, if the most
disabling penetrations would be less
than the penetrations described in this
paragraph, the smaller penetration
must be assumed.
TABLE 172.235—EXTENT OF DAMAGE
Collision Penetration
Longitudinal extent .........

Transverse extent ..........
Vertical extent ................

0.495 L2/3 or 47.6 feet.
(1/3 L2/3 or 14.5 m), whichever is
less.
4 feet 2 inches (1.25 m).1
From the baseline upward without
limit.

Grounding Penetration Forward of a Point 0.3L Aft of the
Forward Perpendicular
Longitudinal ....................

0.495 L2/3 or 47.6 feet.
(1/3 L2/3 or 14.5 m), whichever is
less.

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§ 172.245

TABLE 172.235—EXTENT OF DAMAGE—
Continued
Transverse .....................

Vertical extent ................

B/6 or 32.8 feet (10 m), whichever
is less, but not less than 16.4
feet (5 m).1
0.75 m from the baseline.

Grounding Penetration at Any Other Longitudinal Position
Longitudinal extent .........
Transverse .....................
Vertical extent ................

L/10 or 16.4 feet (5 m), whichever
is less.
4 feet 2 inches (1.25 m).
2 feet 6 inches (0.75 m) from the
baseline.

1 Damage applied inboard from the vessel’s side at right angles to the centerline at the level of the summer load line assigned under Subchapter E of this chapter.

§ 172.240 Permeability of spaces.
When doing the calculations required
in § 172.225,
(a) The permeability of a floodable
space, other than a machinery or cargo
space, must be assumed as listed in
Table 172.240;
(b) Calculations in which a machinery space is treated as a floodable
space must be based on an assumed machinery space permeability of 85% unless the use of an assumed permeability
of less than 85% is justified in detail;
and
(c) Calculations in which a cargo
space that is completely filled is considered flooded must be based on an assumed cargo space permeability of 60%
unless the use of an assumed permeability of less than 60% is justified in
detail. If the cargo space is not completely filled, a cargo space permeability of 95% must be assumed unless
the use of an assumed permeability of
less than 95% is justified in detail.
TABLE 172.240—PERMEABILITY
Permeability (percent)

Spaces and tanks
Storeroom spaces .................................
Accommodations spaces .......................
Voids ......................................................
Consumable liquid tanks .......................
Other liquid tanks ..................................
Cargo (completely filled) ........................
Cargo (empty) ........................................
Machinery ..............................................

60
95
95
1 95 or 0
2 95 or 0
60
95
85

1 Whichever

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results in the more disabling condition.
2 If tanks are partially filled, the permeability must be determined from the actual density and amount of liquid carried.

§ 172.245 Survival conditions.
A vessel is presumed to survive assumed damage if it meets the following

conditions in the final stage of flooding:
(a) Final waterline. The final waterline, in the final condition of sinkage,
heel, and trim must be below the lower
edge of an opening through which progressive flooding may take place, such
as an air pipe, or an opening that is
closed by means of a weathertight door
or hatch cover. This opening does not
include an opening closed by a:
(1) Watertight manhole cover;
(2) Flush scuttle;
(3) Small watertight cargo tank
hatch cover that maintains the high
integrity of the deck;
(4) Class 1 door in a watertight bulkhead;
(5) Remotely operated sliding watertight door;
(6) Side scuttle of the nonopening
type;
(7) Retractable inflatable seal; or
(8) Guillotine door.
(b) Heel angle. The maximum angle of
heel must not exceed 15 degrees, except
that this angle may be increased to 17
degrees if no deck edge immersion occurs.
(c) Range of stability. Through an
angle of 20 degrees beyond its position
of equilibrium after flooding, a vessel
must meet the following conditions:
(1) The righting arm curve must be
positive.
(2) The maximum righting arm must
be at least 4 inches (10 cm).
(3) Each submerged opening must be
weathertight
(d) Metacentric height. After flooding,
the metacentric height must be at
least 2 inches (50 mm) when the vessel
is in the equilibrium position.
(e) Progressive flooding. In the design
calculations required by § 172.225, progressive flooding between spaces connected by pipes, ducts or tunnels must
be assumed unless:
(1) Pipes within the assumed extent
of damage are equipped with arrangements such as stop check valves to prevent progressive flooding to other
spaces with which they connect; and,
(2) Progressive flooding through
ducts or tunnels is protected against
by:
(i) Retractable inflatable seals to
cargo hopper gates; or

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46 CFR Ch. I (10–1–11 Edition)

(ii) Guillotine doors in bulkheads in
way of the conveyor belt.

Comp., p. 277; Department of Homeland Security Delegation No. 0170.1.
SOURCE: CGD 79–023, 48 FR 51045, Nov. 4,
1983, unless otherwise noted.

PART 173—SPECIAL RULES
PERTAINING TO VESSEL USE

Subpart A—General
Subpart A—General
Sec.
173.001

§ 173.001
Applicability.

Subpart B—Lifting
173.005 Specific applicability.
173.007 Location of the hook load.
173.010 Definitions.
173.020 Intact
stability
standards:
Counterballasted
and
noncounterballasted vessels.
173.025 Additional intact stability standards: Counterballasted vessels.

Subpart C—School Ships

Subpart B—Lifting
§ 173.005

Specific applicability.

173.050 Specific applicability.
173.051 Public nautical school ships.
173.052 Civilian nautical school ships.
173.053 Sailing school vessels.
173.054 Watertight subdivision and damage
stability standards for new sailing school
vessels.
173.055 Watertight subdivision and damage
stability standards for existing sailing
school vessels.
173.056 Collision and other watertight bulkheads.
173.057 Permitted locations for Class I watertight doors.
173.058 Double bottom requirements.
173.059 Penetrations and openings in watertight bulkheads.
173.060 Openings in the side of a vessel
below the bulkhead or weather deck.
173.061 Watertight integrity above the margin line.
173.062 Drainage of weather deck.
173.063 Intact stability requirements.

This subpart applies to each vessel
that—
(a) Is equipped to lift cargo or other
objects; and
(b) Has a maximum heeling moment
due to hook load greater than or equal
to—

Subpart D—Oceanographic Research

When doing the calculations required
in this subpart, the hook load must be
considered to be located at the head of
the crane.

173.070
173.075
173.080
173.085

Specific applicability.
Subdivision requirements.
Damage stability requirements.
General subdivision requirements.

(0.67)(W)(GM)(F/B) in meter-metric tons
(foot-long tons), where—
W=displacement of the vessel with the hook
load included in metric (long) tons.
GM=metacentric height with hook load included in meters (feet).
F=freeboard to the deck edge amidships in
meters (feet).
B=beam in meters (feet).
[CGD 79–023, 48 FR 51045, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 945, Jan. 10,
1996]

§ 173.007

§ 173.010
Subpart E—Towing
173.090
173.095
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Applicability.

Each vessel that is engaged in one of
the following activities must comply
with the applicable provisions of this
part:
(a) Lifting.
(b) Training (schoolship).
(c) Oceanographic research.
(d) Towing.

General.
Towline pull criterion.

AUTHORITY: 43 U.S.C. 1333; 46 U.S.C. 2113,
3306, 5115; E.O. 12234, 45 FR 58801, 3 CFR, 1980

Location of the hook load.

Definitions.

As used in this part—
(a) Hook load means the weight of the
object lifted by the crane.
(b) Crane radius means the distance
illustrated in Figure 173.010.

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Coast Guard, DHS

§ 173.025

§ 173.020 Intact stability standards:
Counterballasted
and
noncounterballasted vessels.
(a) Except as provided in paragraph
(c) of this section, each vessel that is
not equipped to counter-ballast while
lifting must be shown by design calculations to comply with this section
in each condition of loading and operation and at each combination of hook
load and crane radius.
(b) Each vessel must have a righting
arm curve with the following characteristics:
(1) If the vessel operates in protected
or partially protected waters, the area
under the righting arm curve up to the
smallest of the following angles must
be at least 10 foot-degrees (3.05 meterdegrees):
(i) The angle corresponding to the
maximum righting arm.
(ii) The downflooding angle.
(iii) 40 degrees.
(2) If the vessel operates in exposed
waters, the area under the righting
arm curve up to the smallest of the following angles must be at least 15 footdegrees (4.57 meter-degrees):
(i) The angle corresponding to the
maximum righting arm.
(ii) The downflooding angle.
(iii) 40 degrees.
(c) If the vessel’s hull proportions fall
within all three of the following limits,
in lieu of complying with paragraph (b)

[CGD 79–023, 48 FR 51045, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 945, Jan. 10,
1996]

§ 173.025 Additional intact stability
standards: Counterballasted vessels.
(a) Each vessel equipped to counterballast while lifting must be shown by
design calculations to be able to withstand the sudden loss of the hook load,
in each condition of loading and operation and at each combination of hook
load and crane radius.
(b) When doing the calculations required by this section, the hook load
and counterballast heeling arms and
vessel righting arms, as plotted on
graph 173.025, must define areas that
satisfy the following equation:
Area II > Area I + K
Where—
(1) K=O for operation on protected waters
and 7 foot-degrees (2.13 meter-degrees) for
operation on partially protected and exposed waters.
(2) Areas I and II are shown on graph 173.025.

(c) Each heeling arm curve must be
defined by—
HA=HAO cos (T)
Where—
HA=heeling arm.
HAO=heeling arm at 0 degrees of heel.
T=angle of heel.

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of this section, the vessel owner may
demonstrate in the presence of the
OCMI that the vessel will not heel beyond the limits specified in paragraph
(d) of this section:
(1) Beam to depth—3.40 to 4.75.
(2) Length to beam—3.20 to 4.50.
(3) Draft to depth—0.60 to 0.85.
(d) For the purpose of paragraph (c)
of this section, the following limits of
heel apply with the vessel at its deepest operating draft:
(1) Protected and partially protected
waters and Great Lakes in summer—
heel to main deck immersion or bilge
emergence, whichever occurs first.
(2) Exposed waters and Great Lakes
in winter—heel permitted to one-half
of the freeboard or one-half of the
draft, whichever occurs first.

§ 173.050

46 CFR Ch. I (10–1–11 Edition)

Where—

Subpart C—School Ships

[CGD 79–023, 48 FR 51045, Nov. 4, 1983, as
amended by CGD 85–080, 61 FR 945, Jan. 10,
1996]

§ 173.050

Specific applicability.

Each nautical school ship, inspected
under Subchapter R of this chapter,
must comply with this subpart.
§ 173.051

Public nautical school ships.

Each public nautical school ship
must comply with—
(a) Section 171.070(a) of this subchapter as a passenger vessel carrying
400 or less passengers;
(b) Section 171.070(e) of this subchapter;
(c) Section 171.072 of this subchapter;
and
(d) Section 171.073 of this subchapter.
[CGD 79–023, 48 FR 51045, Nov. 4, 1983. Redesignated by CGD 83–005, 51 FR 924, Jan. 9, 1986]

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GZ(1) is the righting arm curve at the displacement corresponding to the vessel
without hooking load.
GZ(2) is the righting arm curve at the displacement corresponding to the vessel with
hook load.
HA(1) is the heeling arm curve due to the
combined heeling moments of the hook
load and the counterballast at the displacement with hook load.
HA(2) is the heeling arm due to the counterballast at the displacement without hook
load.
Theta(c) is the angle of static equilibrium
due to the combined hook load and
counterballast heeling moments.
Theta(f) is the downflooding angle on the
counterballasted side of the vessel.

Coast Guard, DHS

§ 173.055

§ 173.052 Civilian
nautical
school
ships.
Each civilian nautical school ship
must comply with part 171 of this subchapter as though it were a passenger
vessel. In addition to regular passengers, for the purpose of complying
with part 171, the following will also
count as passengers;
(a) A student.
(b) A cadet.
(c) An instructor who is not also a
member of the crew.
[CGD 79–023, 48 FR 51045, Nov. 4, 1983. Redesignated by CGD 83–005, 51 FR 924, Jan. 9, 1986]

§ 173.053 Sailing school vessels.
(a) In addition to the requirements in
§§ 173.054 through 173.063, each sailing
school vessel must comply with the
provisions of subpart A of part 171 of
this subchapter.
(b) In addition to regular passengers,
for the purpose of complying with
§§ 171.070 through 171.073 and § 171.080,
the following will also be counted as
passengers:
(1) Sailing school students.
(2) Sailing school instructors.
(3) Guests.

pmangrum on DSK3VPTVN1PROD with CFR

[CGD 83–005, 51 FR 924, Jan. 9, 1986]

§ 173.054 Watertight subdivision and
damage stability standards for new
sailing school vessels.
(a) Each new sailing school vessel
which has a mean length greater than
75 feet (22.8 meters) or which carries
more than 30 persons must comply
with—
(1) Section 179.210(a) of this chapter;
(2) Sections 171.070 through 171.073;
and
(3) Section 171.080 for Type II subdivision and damage stability.
(b) Each new sailing school vessel
which has a mean length of 75 feet (22.8
meters) or less and carries more than
30 persons must comply with either—
(1) Section 179.210(a) of this chapter
and § 179.220 of this chapter; or
(2) Section 171.040(a)(1), §§ 171.070
through 171.073, and § 171.080.
(c) Each new sailing school vessel
which does not carry more than 30 persons must have a collision bulkhead
unless it has a mean length less than 40
feet (12.2 meters) and is certificated for

protected or partially protected waters
service only.
[CGD 83–005, 51 FR 924, Jan. 9, 1986, as amended by CGD 85–080, 61 FR 946, Jan. 10, 1996]

§ 173.055 Watertight subdivision and
damage stability standards for existing sailing school vessels.
(a) Except as provided in paragraph
(c) of this section, an existing sailing
school vessel which carries more than
49 persons must be fitted with a collision bulkhead and any additional bulkheads necessary to provide one compartment subdivision.
(b) Except as provided in paragraph
(c) of this section, an existing sailing
school vessel which has a mean length
greater than 65 feet (19.8 meters), must
be fitted with additional transverse watertight bulkheads necessary to provide one compartment subdivision,
when the following Subdivision Numerals are exceeded:
(1) For vessels to be operated on Exposed Waters:
L × N > 4000
(2) For vessels to be operated on Partially Protected Waters:
L × N > 4500
(3) For vessels to be operated on Protected Waters:
L × N > 5000
where L is the mean length and N is the
number of persons on board

(c) An existing sailing school vessel
which is required to meet a one compartment subdivision standard and has
a mean length of 90 feet (27.4 meters) or
less may, instead of one compartment
subdivision, be fitted with a collision
bulkhead and sufficient air tankage or
other internal buoyancy to maintain
the fully-loaded vessel afloat with positive stability in the flooded condition.
(d) Except as provided in paragraph
(e) of this section, an existing sailing
school vessel which has a mean length
greater than 65 feet (19.8 meters) must
be fitted with a collision bulkhead.
(e) On an existing sailing school vessel, operating on protected waters,
which has a mean length of 90 feet (27.4
meters) or less with no other requirement for subdivision, the collision
bulkhead may be omitted.

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46 CFR Ch. I (10–1–11 Edition)

(f) An existing sailing school vessel,
operating on exposed waters, which has
a mean length of 65 feet (19.8 meters) or
less and is carrying more than 15 persons, must be fitted with a collision
bulkhead.
[CGD 83–005, 51 FR 924, Jan. 9, 1986]

§ 173.056 Collision and other watertight bulkheads.
(a) Collision bulkheads required by
this section must comply with the requirements in § 171.085 of this subchapter.
(b) Each sailing school vessel required to meet paragraph (a) of § 173.054
must comply with the machinery space
bulkhead requirements in § 171.095 of
this subchapter.
[CGD 83–005, 51 FR 924, Jan. 9, 1986]

§ 173.057 Permitted locations for Class
I watertight doors.
(a) Class I doors are permitted in any
location on a sailing school vessel
which has a mean length of 125 feet
(38.1 meters) or less.
(b) Class I doors fitted in accordance
with § 170.270 of this subchapter shall
additionally be marked in two-inch letters ‘‘RECLOSE AFTER USE’’, and be
provided with a remote position indicator at the main navigating station of
the vessel.
[CGD 83–005, 51 FR 924, Jan. 9, 1986]

§ 173.058

Double bottom requirements.

Each new sailing school vessel which
has a mean length greater than 165 feet
(50.3 meters) and is certificated for exposed water service must comply with
the double bottom requirements in
§§ 171.105 through 171.109, inclusive, of
this subchapter.
[CGD 83–005, 51 FR 924, Jan. 9, 1986]

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§ 173.059 Penetrations and openings in
watertight bulkheads.
Penetrations and openings in watertight bulkheads must comply with the
requirements in subpart E of part 171 of
this subchapter or §§ 179.320, 179.330, and
179.340 in subchapter T of this chapter.
[CGD 83–005, 51 FR 924, Jan. 9, 1986, as amended by CGD 85–080, 61 FR 946, Jan. 10, 1996]

§ 173.060 Openings in the side of a vessel below the bulkhead or weather
deck.
(a) Openings in the side of a vessel
below the bulkhead or weather deck
must comply with the requirements in
subpart F of part 171 of this subchapter
or § 179.350 in subchapter T of this chapter.
(b) In addition to the requirements in
paragraph (a) of this section, each sailing school vessel which has a mean
length greater than 90 feet must comply with the requirements in § 56.50–95
of Subchapter F of this chapter.
[CGD 83–005, 51 FR 924, Jan. 9, 1986, as amended by CGD 85–080, 61 FR 945, Jan. 10, 1996]

§ 173.061 Watertight integrity above
the margin line.
The watertight integrity of each sailing school vessel above the margin line
must comply with the requirements in
subpart G of part 171 of this subchapter
or § 179.360 in subchapter T of this chapter.
[CGD 83–005, 51 FR 925, Jan. 9, 1986, as amended by CGD 85–080, 61 FR 946, Jan. 10, 1996; 61
FR 20556, May 7, 1996]

§ 173.062 Drainage of weather deck.
The weather deck of each sailing
school vessel must be provided with
drainage in accordance with the requirements in subpart H of part 171 of
this subchapter or subpart D of part 178
in subchapter T of this chapter.
[CGD 83–005, 51 FR 925, Jan. 9, 1986, as amended by CGD 85–080, 61 FR 946, Jan. 10, 1996]

§ 173.063 Intact stability requirements.
(a) Except as provided in this section,
each sailing school vessel must meet
the intact stability requirements in
§§ 170.170, 171.050, and 171.055 of this
chapter.
(b) In applying the requirements in
§§ 170.170 and 171.050 of this subchapter,
the value of ‘‘T’’ is equal to the angle
of heel at which the deck edge is immersed or 1⁄3 of the downflooding angle,
whichever is less.
(c) In applying the requirements of
§ 171.055(d) (1) and (2) of this subchapter—
(1) The value ‘‘X’’ is equal to 0.6 long
tons/square foot (9.8 metric tons/square
meter).

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Coast Guard, DHS

§ 173.063

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(2) For a vessel in service on protected or partially protected waters,
values ‘‘Y’’ and ‘‘Z’’ are determined
from graphs 173.063 (a) and (b) and multiplied by the multiplier in graph
173.063(e).
(3) For a vessel in service on exposed
waters, ‘‘Y’’ and ‘‘Z’’ are determined
from graphs 173.063 (c) and (d) and multiplied by the multiplier from graph
173.063(e).
(4) To convert required numerals to
units of ‘‘metric tons/square meter,’’
multiply by 10.94.
(d) Each vessel of the open boat type
that is required to comply with the requirements in §§ 178.300 and 178.310 of

this chapter, may instead comply with
the requirements in paragraph (e) of
this section.
(e) In lieu of complying with the requirements of paragraph (b) of this section, an open boat may be provided
with sufficient air tankage or other internal buoyancy to maintain the vessel
afloat when the vessel is completely
flooded or capsized. If foam is used to
comply with this paragraph, it must be
installed in accordance with the requirements in § 170.245 of this subchapter.
(f) A sailing school catamaran must
meet the intact stability requirements
in § 171.057.

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§ 173.063

§ 173.063

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Coast Guard, DHS

§ 173.063

46 CFR Ch. I (10–1–11 Edition)

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[CGD 83–005, 51 FR 925, Jan. 9, 1986, as amended by CGD 85–080, 61 FR 946, Jan. 10, 1996]

Coast Guard, DHS

§ 173.095

Subpart D—Oceanographic
Research
§ 173.070 Specific applicability.
Each oceanographic vessel, inspected
under Subchapter U of this chapter, except a barge that is less than 300 gross
tons, must comply with this subpart.
§ 173.075 Subdivision requirements.
(a) Each oceanographic vessel must
comply with the subdivision requirements in §§ 171.070, 171.072, and 171.073 of
this subchapter as if it were a passenger vessel carrying 400 or less passengers.
(b) Each vessel must have a collision
bulkhead.

§ 173.085 General subdivision requirements.
Each oceanographic vessel must comply with the following:
(a) Section 171.085(c)(1), (d) and (g) of
this subchapter.
(b) Section 171.105 (a) through (g) of
this subchapter except that a reduction
or elimination of the required inner
bottom is allowed if—
(1) The inner bottom would interfere
with the mission of the vessel; and
(2) As a result of other design features, the ability of the vessel to withstand side and bottom damage is not
reduced.
(c) Section 171.106 of this subchapter.
(d) Section 171.108 of this subchapter.
(e) Section 171.109 of this subchapter.
(f) Section 171.111 of this subchapter.
(g) Section 171.113 of this subchapter.
(h) The collision bulkhead must not
be penetrated by more than one pipe
that carries liquid to or from the
forepeak tank. This pipe must have a
screwdown valve that is—
(1) Operative from above the bulkhead deck; and
(2) Attached to the bulkhead inside
the forepeak tank.
(i) Section 171.116 (b), (c), and (e) of
this subchapter.
(j) Section 171.117(c) of this subchapter.

Subpart E—Towing
§ 173.090 General.
This subpart applies to each vessel
that is equipped for towing.
§ 173.095 Towline pull criterion.
(a) In each towing condition, each
vessel must be shown by design calculations to meet the requirements of
either paragraph (b) or (c) of this section.
(b) The vessel’s metacentric height
(GM) must be equal to or greater than
the following:

GM =

(N)(P × D) 2 3 (s)(h)
KΔ (f / B)

where—
N=number of propellers.
P=shaft power per shaft in horsepower (kilowatts).
D=propeller diameter in feet (meters).
s=that fraction of the propeller circle cylinder which would be intercepted by the
rudder if turned to 45 degrees from the vessel’s centerline.
h=vertical distance from propeller shaft centerline at rudder to towing bitts in feet
(meters).
D=displacement in long tons (metric tons).
f=minimum freeboard along the length of the
vessel in feet (meters).
B=molded beam in feet (meters).

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§ 173.080 Damage stability requirements.
Each oceanographic vessel must comply with § 171.080 of this subchapter as a
category Z vessel.

(k) Each port light in a space located
below the freeboard deck, as defined in
§ 42.13–15(i) of this chapter, or in a
space within an enclosed superstructure must be fitted with a hinged
inside dead cover.
(l) Section 171.118 (b) and (c) of this
subchapter.
(m) Section 171.122 (a) through (d)
and (f) of this subchapter.
(n) Section 171.135 of this subchapter.
(o) A ventilation duct or forced draft
duct may not penetrate a main transverse watertight bulkhead unless—
(1) The penetration is watertight;
(2) The penetration is located as near
the vessel’s centerline as possible; and
(3) The bottom of the duct is not
more than—
(i) 18 inches (45.7 cm) below the bulkhead deck; and
(ii) 4 feet (121.9 cm) above the final
waterline after damage determined in
§ 173.080.

Pt. 174

46 CFR Ch. I (10–1–11 Edition)
174.015
174.020

K=38 in English units.
K=13.93 in metric units.

(c) When a heeling arm curve, calculated in accordance with paragraph
(d) of this section, is plotted against
the vessel’s righting arm curve—
(1) Equilibrium must be reached before the downflooding angle; and
(2) The residual righting energy must
be at least 2 foot-degrees (.61 meter-degrees) up to the smallest of the following angles:
(i) The angle of maximum righting
arm.
(ii) The downflooding angle.
(iii) 40 degrees.
(d) The heeling arm curve specified in
paragraph (c) of this section must be
calculated by the following equation:

HA =

2 (N)(P × D) 2 3
(s)(h)(cos θ)

174.030 Specific applicability.
174.035 Definitions.
174.040 Stability requirements: general.
174.045 Intact stability requirements.
174.050 Stability on bottom.
174.055 Calculation of wind heeling moment
(Hm).
174.065 Damage stability requirements.
174.070 General damage stability assumptions.
174.075 Compartments assumed flooded: general.
174.080 Flooding on self-elevating and surface type units.
174.085 Flooding on column stabilized units.
174.090 Permeability of spaces.
174.100 Appliances
for
watertight
and
weathertight integrity.

Subpart E—Special Rules Pertaining to
Tugboats and Towboats

KΔ

(e) For the purpose of this section,
downflooding angle means the static
angle from the intersection of the vessel’s centerline and waterline in calm
water to the first opening that does not
close watertight automatically.
(f) For the purpose of this section, at
each angle of heel, a vessel’s righting
arm may be calculated considering either—
(1) The vessel is permitted to trim
free until the trimming moment is
zero; or
(2) The vessel does not trim as it
heels.

PART 174—SPECIAL RULES PERTAINING TO SPECIFIC VESSEL
TYPES

174.140
174.145

Subpart F [Reserved]
Subpart G—Special Rules Pertaining to
Offshore Supply Vessels
174.180 Applicability.
174.185 Intact stability.
174.190 Collision bulkhead.
174.195 Bulkheads in machinery spaces.
174.200 Damaged stability in machinery
spaces for all OSVs.
174.205 Additional damaged stability for
OSVs carrying more than 16 offshore
workers.
174.207 Damaged stability criteria.
174.210 Watertight doors in watertight bulkheads.
174.215 Drainage of weather deck.
174.220 Hatches and coamings.
174.225 Hull penetrations and shell connections.

Subpart H—Special Rules Pertaining to
Liftboats

Applicability.
Incorporation by reference.

Subpart B—Special Rules Pertaining to
Deck Cargo Barges
174.010

Specific applicability.
Intact stability requirements.

174.240 Applicability.
174.245 General.
174.250 Unrestricted service.
174.255 Restricted service.
174.260 Freeboard.

Subpart A—General

Subpart I—Hopper Dredges With Working
Freeboard Assignments
174.300

Specific applicability.

Specific applicability.

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Subpart C—Special Rules Pertaining to
Mobile Offshore Drilling Units

Subpart D [Reserved]

where—
HA=heeling arm.
q=angle of heel.
N, P, D, K, s, h, and D are as defined in paragraph (b) of this section.

Sec.
174.005
174.007

Intact stability.
Alternate intact stability criterion.

Coast Guard, DHS
174.305

§ 174.010

Definitions.
CALCULATIONS

174.310
174.315
174.320
174.325
174.330

General.
Extent and character of damage.
Damage survival.
Equalization.
Jettisoning of spoil.

174.335
174.340

Watertight doors.
Collision bulkhead.

DESIGN

Subpart J—Special Rules Pertaining to Dry
Cargo Ships
174.350 Specific applicability.
174.355 Definitions.
174.360 Calculations.
AUTHORITY: 42 U.S.C. 9118, 9119, 9153; 43
U.S.C. 1333; 46 U.S.C. 3306, 3703; E.O. 12234, 45
FR 58801, 3 CFR, 1980 Comp., p. 277; Department of Homeland Security Delegation No.
0170.1.
SOURCE: CGD 79–023, 48 FR 51048, Nov. 4,
1983, unless otherwise noted.

Subpart A—General
§ 174.005 Applicability.
Each of the following vessels must
comply with the applicable provisions
of this part:
(a) Deck cargo barge.
(b) Mobile offshore drilling unit
(MODU) inspected under subchapter IA
of this chapter.
(c) Tugboat and towboat inspected
under subchapter I of this chapter.
(d) Self-propelled hopper dredge having an assigned working freeboard.
(e) Oceangoing ships of 500 gross tons
or over, as calculated by the International Convention on Tonnage Measurement of Ships, 1969, designed primarily for the carriage of dry cargoes,
including roll-on/roll-off ships.
(f) Offshore supply vessel inspected
under subchapter L of this chapter.
(g) Liftboat inspected under subchapter L of this chapter.

pmangrum on DSK3VPTVN1PROD with CFR

[CGD 95–012, 60 FR 48052, Sept. 18, 1995; 60 FR
50120, Sept. 28, 1995, as amended by CGD 82–
004 and CGD 86–074, 60 FR 57671, Nov. 16, 1995;
CGD 82–004 and CGD 86–074, 62 FR 49353, Sept.
19, 1997]

§ 174.007 Incorporation by reference.
(a) Certain material is incorporated
by reference into this part with the approval of the Director of the Federal

Register under 5 U.S.C. 552(a) and 1
CFR part 51. To enforce any edition
other than that specified in this section, the Coast Guard must publish a
notice of change in the FEDERAL REGISTER and the material must be available to the public. All approved material is available for inspection at the
National Archives and Records Administration (NARA). For information on
the availability of this material at
NARA, call 202–741–6030 or go to http://
www.archives.gov/federallregister/
codeloflfederallregulations/
ibrllocations.html. It is also available
for inspection at the Coast Guard, Office of Design and Engineering Standards, Naval Architecture Division (CG–
5212), 2100 2nd St. SW., Stop 7126, Washington, DC 20593–7126, and is available
from the sources listed below.
(b) American Society for Testing and
Materials (ASTM) 100 Barr Harbor
Drive, West Conshohocken, PA 19428–
2959.
(1) ASTM F 1196–00, Standard Specification for Sliding Watertight Door
Assemblies, 2008, incorporation by reference (IBR) approved for § 174.100.
(2) ASTM F 1197–00, Standard Specification for Sliding Watertight Door
Control Systems, 2007, IBR approved
for § 174.100.
(c) International Maritime Organization (IMO), Publications Section, 4 Albert Embankment, London SE1 7SR,
United Kingdom, +44 (0)20 7735 7611,
http://www.imo.org/.
(1) Resolution MSC.216(82), Adoption
of Amendments to the International
Convention for the Safety of Life At
Sea, 1974, As Amended (IMO Res.
MSC.216(82)), Adopted on 8 December
2006, IBR approved for § 174.360.
(2) [Reserved]
[USCG–2007–0030, 75 FR 78086, Dec. 14, 2010]

Subpart B—Special Rules
Pertaining to Deck Cargo Barges
§ 174.010

Specific applicability.

Each barge that carries cargo above
the weather deck must comply with
this subpart.

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§ 174.015
§ 174.015

46 CFR Ch. I (10–1–11 Edition)
Intact stability.

(a) Except as provided in § 174.020, in
each condition of loading and operation, each barge must be shown by design calculations to have an area under
the righting arm curve up to the angle
of
maximum
righting
arm,
the
downflooding angle, or 40 degrees,
whichever angle is smallest, equal to or
greater than—
(1) 15 foot-degrees (4.57 meter-degrees) for ocean and Great Lakes winter service; and
(2) 10 foot-degrees (3.05 meter-degrees) for lakes, bays, sounds, and
Great Lakes summer service.
(b) For the purpose of this section,
downflooding angle means the static
angle from the intersection of the vessel’s centerline and waterline in calm
water to the first opening that does not
close watertight automatically.
§ 174.020 Alternate intact stability criterion.
A barge need not comply with
§ 174.015 and subparts C and E of part
170 of this chapter if it has the following characteristics:
(a) The weather deck is watertight.
(b) The barge’s hull proportions fall
within any one of the ratios in categories (A) through (D) in Table 174.020.
(c) The maximum cargo height is 30
feet (9.25 meters) or a value equal to
the depth of the barge amidships,
whichever is less.
TABLE 174.020
Category

Beam/depth ratio

A ............................

3.00 to 3.74 .........

B ............................

3.75 to 3.99 .........

C ............................

4.00 to 4.49 .........

D ............................

4,50 to 6.00 .........

Draft/depth ratio
Equal to or less
than 0.70.
Equal to or less
than 0.72.
Equal to or less
than 0.76.
Equal to or less
than 0.80.

Subpart C—Special Rules Pertaining to Mobile Offshore
Drilling Units

§ 174.035 Definitions.
(a) For the purpose of this subpart
the following terms have the same definitions as given in Subchapter IA of
this chapter:
(1) Column stabilized unit.
(2) Mobile offshore drilling unit.
(3) Self-elevating unit.
(4) Surface type unit.
(b) For the purpose of this subpart—
(1) Downflooding means the entry of
seawater through any opening that
cannot be rapidly closed watertight,
into the hull, superstructure, or columns of an undamaged unit due to
heel, trim, or submergence of the unit.
(2) Downflooding angle means the
static angle from the intersection of
the unit’s centerline and waterline in
calm water to the first opening
through which downflooding can occur
when subjected to a wind heeling moment (Hm) calculated in accordance
with § 174.055.
(3) Normal operating condition means a
condition of a unit when loaded or arranged for drilling, field transit, or
ocean transit.
(4) Severe storm condition means a condition of a unit when loaded or arranged to withstand the passage of a
severe storm.
§ 174.040 Stability requirements: general.
Each unit must be designed to have
at least 2 inches (50mm) of positive
metacentric height in the upright equilibrium position for the full range of
drafts, whether at the operating draft
for navigation, towing, or drilling
afloat, or at a temporary draft when
changing drafts.
§ 174.045 Intact stability requirements.
(a) Each unit must be designed so
that the wind heeling moments (Hm)
and righting moments calculated for
each of its normal operating conditions
and severe storm conditions, when
plotted on GRAPH 174.045, define areas
that satisfy the equation:
Area(A)≥(K)×(Area (B))

pmangrum on DSK3VPTVN1PROD with CFR

§ 174.030

Specific applicability.

Each mobile offshore drilling unit
(MODU) inspected under Subchapter IA
of this chapter must comply with this
subpart.

where—
(1) K=1.4 except that if the unit is a column
stabilized unit K=1.3;
(2) Area (A) is the area on GRAPH 174.045
under the righting moment curve between

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Coast Guard, DHS

§ 174.045

0 and the second intercept angle or the
angle of heel at which downflooding would
occur, whichever angle is less; and
(3) Area (B) is the area on GRAPH 174.045
under the wind heeling moment curve between 0 and the second intercept angle or
the angle of heel at which downflooding of
the unit would occur whichever angle is
less.

[CGD 79–023, 48 FR 51048, Nov. 4, 1983, as amended by CGD 83–071, 52 FR 6979, Mar. 6, 1987]

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(b) Each righting moment on graph
§ 174.045 must be positive for all angles
greater than 0 and less than the second
intercept angle.
(c) For the purposes of this section,
openings fitted with the weathertight
closing
appliances
specified
in
§ 174.100(b) are not considered as openings through which downflooding could

occur if they can be rapidly closed and
would not be submerged below the
units’ waterline prior to the first intercept angle, except that ventilation intakes and outlets for machinery
spaces, crew spaces, and other spaces
where ventilation is normally required
are considered as openings through
which downflooding could occur regardless of location.
(d) Each unit must be designed so
that it can be changed from each of its
normal operating conditions to a severe storm condition within a minimum period of time consistent with
the operating manual required in
§ 109.121 of this chapter.

§ 174.050

46 CFR Ch. I (10–1–11 Edition)

§ 174.050 Stability on bottom.
Each bottom bearing unit must be
designed so that, while supported on
the sea bottom with footings or a mat,
it continually exerts a downward force
on each footing or the mat when subjected to the forces of wave and current
and to wind blowing at the velocities
described in § 174.055(b)(3).

and back sides of the open truss work
rather than by determining the projected area of each structural member
of the truss work.

§ 174.055 Calculation of wind heeling
moment (Hm).
(a) The wind heeling moment (Hm) of
a unit in a given normal operating condition or severe storm condition is the
sum of the individual wind heeling moments (H) calculated for each of the exposed surfaces on the unit; i.e., Hm=S
H.
(b) Each wind heeling moment (H)
must be calculated using the equation:
H=k(v)2(Ch)(Cs)(A)(h)

pmangrum on DSK3VPTVN1PROD with CFR

where—
(1) H=wind heeling moment for an exposed
surface on the unit in foot-pounds (kilogram-meters);
(2) k=0.00338 lb./(ft.2-knots2) (0.0623 (kg-sec2)/
m4);
(3) v=wind velocity of—
(i) 70 knots (36 meters per second) for normal
operating conditions.
(ii) 100 knots (51.5 meters per second) for severe storm conditions.
(iii) 50 knots (25.8 meters per second) for
damage conditions.
(4) A=projected area in square feet (squrae
meters) of an exposed surface on the unit;
(5) Ch=height coefficient for ‘‘A’’ from Table
174.055(a);
(6) Cs=shape coefficient for ‘‘A’’ from Table
174.055(b); and
(7) h=the vertical distance in feet (meters)
from the center of lateral resistance of the
underwater hull to the center of wind pressure on ‘‘A’’.

(c) When calculating ‘‘A’’ in the
equation described in paragraph (b) of
this section—
(1) The projected area of each column
or leg; if the unit has columns or legs,
must not include shielding allowances;
(2) Each area exposed as a result of
heel must be included;
(3) The projected area of a cluster of
deck houses may be used instead of the
projected area of each individual deck
house in the cluster; and
(4) The projected area of open truss
work may be calculated by taking 30%
of the projected areas of both the front

TABLE 174.055(a)—CH VALUES
Feet

Meters

Over

Not exceeding

Over

0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
Above 850

50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850

0.0
15.3
30.5
46.0
61.0
76.0
91.5
106.5
122.0
137.0
152.5
167.5
183.0
198.0
213.5
228.5
244.0
Above 256

Not exceeding

Ch.

15.3
30.5
46.0
61.0
76.0
91.5
106.5
2.0 .........
137.0
152.5
167.5
183.0
198.0
213.5
228.5
244.0
256.0

1.00
1.10
1.20
1.30
1.37
1.43
1.48
1.52
1.56
1.60
1.63
1.67
1.70
1.72
1.75
1.77
1.79
1.80

NOTE: The ‘‘Ch’’ value in this table, used in the equation described in section § 174.055(b), corresponds to the value of
the vertical distance in feet (meters) from the water surface at
the design draft of the unit to the center of area of the ‘‘A’’
value used in the equation.

TABLE 174.055(b)—CS VALUES
Shape

Cs.

Cylindrical shapes .........................................................
Hull (surface type) .........................................................
Deckhouse .....................................................................
Cluster of deckhouses ...................................................
Isolated structural shapes (cranes, angles, channels,
beams, etc.) ...............................................................
Under deck areas (smooth surfaces) ............................
Under deck areas (exposed beams and girders) .........
Rig derrick (each face and open truss works) ..............

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1.0
1.3
1.25

NOTE: The ‘‘Cs’’ value in this table, used in the equation described in § 174.055(b), corresponds to the shape of the projected ‘‘A’’ in the equation.

§ 174.065 Damage
ments.

stability

require-

(a) Each unit must be designed so
that, while in each of its normal operating conditions and severe storm conditions, its final equilibrium waterline
would remain below the lowest edge of
any opening through which additional
flooding could occur if the unit were
subjected simultaneously to—
(1) Damage causing flooding described in §§ 174.075 through 174.085; and
(2) A wind heeling moment calculated in accordance with § 174.055(b)
using a wind velocity of 50 knots (25.8
meters per second).

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Coast Guard, DHS

§ 174.090

(b) Each unit must have a means to
close off each pipe, ventilation system,
and trunk in each compartment described in § 174.080 or § 174.085 if any portion of the pipe, ventilation system, or
trunk is within 5 feet (1.5 meters) of
the hull.
§ 174.070 General damage stability assumptions.
For the purpose of determining compliance with § 174.065, the assumptions
are made that during flooding and the
resulting change in the unit’s waterline—
(a) The unit is not anchored or
moored; and
(b) No compartment on the unit is
ballasted or pumped out to compensate
for the flooding described in §§ 174.075
through 174.085.
§ 174.075 Compartments
flooded: general.

assumed

The individual flooding of each of the
compartments described in §§ 174.080
and 174.085 must be assumed for the
purpose of determining compliance
with § 174.065 (a). Simultaneous flooding of more than one compartment
must be assumed only when indicated
in §§ 174.080 and 174.085.
§ 174.080 Flooding on self-elevating
and surface type units.
(a) On a surface type unit or self-elevating unit, all compartments within 5
feet (1.5 meters) of the hull of the unit
between two adjacent main watertight
bulkheads, the bottom shell, and the
uppermost continuous deck or first superstructure
deck
where
superstructures are fitted must be assumed
to be subject to simultaneous flooding.
(b) On the mat of a self-elevating
unit, all compartments of the mat
must be assumed to be subject to individual flooding.

pmangrum on DSK3VPTVN1PROD with CFR

§ 174.085 Flooding
bilized units.

on

column

unit, must be assumed to be subject to
flooding as follows:
(1) When a column is subdivided into
watertight compartments by horizontal watertight flats, all compartments in the column within 5 feet (1.5
meters) of the unit’s waterline before
damage causing flooding must be assumed to be subject to simultaneous
flooding.
(2) When a column is subdivided into
watertight compartments by vertical
watertight bulkheads, each two adjacent compartments must be assumed
subject to simultaneous flooding if the
distance between the vertical watertight bulkheads, measured at the column periphery, is equal to or less than
one-eighth of the column perimeter at
the draft under consideration.
(3) When a column is subdivided into
watertight compartments by horizontal watertight flats and vertical watertight bulkheads, those compartments that are within the bounds described in paragraph (a)(2) of this section and within 5 feet (1.5 meters) of
the unit’s waterline before damage
causing flooding must be assumed to be
subject to simultaneous flooding.
(b) Each compartment in a footing
must be assumed to be subject to individual flooding when any part of the
compartment is within 5 feet (1.5 meters) of the unit’s waterline before
damage causing flooding.
§ 174.090 Permeability of spaces.
When doing the calculations required
in § 174.065—
(a) The permeability of a floodable
space, other than a machinery space,
must be as listed in Table 174.090; and
(b) Calculations in which a machinery space is treated as a floodable
space must be based on an assumed machinery space permeability of 85%, unless the use of an assumed permeability
of less than 85% is justified in detail.

sta-

(a) Watertight compartments that
are outboard of, or traversed by, a
plane which connects the vertical
centerlines of the columns on the periphery of the unit, and within 5 feet
(1.5 meters) of an outer surface of a column or footing on the periphery of the

TABLE 174.090—PERMEABILITY
Permeability
(percent)

Spaces and tanks
Storeroom spaces ............................................
Accommodation spaces ...................................
Voids ................................................................
Consumable liquid tanks ..................................
Other liquid tanks .............................................
1 Whichever

results in the more disabling condition.

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§ 174.100

46 CFR Ch. I (10–1–11 Edition)

pmangrum on DSK3VPTVN1PROD with CFR

2 If tanks are partially filled, the permeability must be determined from the actual density and amount of liquid carried.

§ 174.100 Appliances for watertight
and weathertight integrity.
(a) Appliances to insure watertight
integrity include watertight doors,
hatches, scuttles, bolted manhole covers, or other watertight closures for
openings in watertight decks and bulkheads.
(b) Appliances to insure weathertight
integrity include weathertight doors
and hatches, closures for air pipes, ventilators, ventilation intakes and outlets, and closures for other openings in
deckhouses and superstructures.
(c) Each internal opening equipped
with appliances to insure watertight
integrity that is used intermittently
during operation of the unit while
afloat must meet the following:
(1) Each door, hatch, and scuttle
must—
(i) Be remotely controlled from a
normally manned control station, and
be operable locally from both sides of
the bulkhead; or
(ii) If there is no means of remote
control there must be an alarm system
that signals whether the appliance is
open or closed both locally at each appliance and in a normally manned control station.
(2) Each closing appliance must remain watertight under the design
water pressure of the watertight
boundary of which it is a part.
(d) Each external opening fitted with
an appliance to insure weathertight integrity must be located so that it
would not be submerged below the final
equilibrium waterline if the unit is
subjected simultaneously to—
(1) Damage causing flooding described in §§ 174.075 through 174.085; and
(2) A wind heeling moment calculated in accordance with § 174.055
using a wind velocity of 50 knots (25.8
meters per second).
(e) If a unit is equipped with sliding
watertight doors, each sliding watertight door must—
(1) Be designed, constructed, tested,
and marked in accordance with ASTM
F 1196 (incorporated by reference, see
§ 174.007);
(2) Have controls in accordance with
ASTM F 1197 (incorporated by reference, see § 174.007), except that a re-

mote manual means of closure, as specified in paragraphs 7.1 and 7.5.1, and a
remote mechanical indicator, as specified in paragraph 7.5.2, will not be required; and
(3) If installed in a subdivision bulkhead, meet Supplemental Requirements Nos. S1 and S3 of ASTM F 1196
(incorporated
by
reference,
see
§ 174.007), unless the watertight doors
are built in accordance with plans previously approved by the Coast Guard,
in which case, only Supplemental Requirements Nos. S1 and S3.1.4 of ASTM
F 1196 (incorporated by reference, see
§ 174.007) must be met. In either case,
control systems for watertight doors
must have power supplies, power
sources, installation tests and inspection, and additional remote operating
consoles in accordance with Supplemental Requirements Nos. S1 through
S4 of ASTM F 1197 (incorporated by reference, see § 174.007).
(f) Installations of sliding watertight
door assemblies must be in accordance
with the following:
(1) Before a sliding watertight door
assembly is installed in a vessel, the
bulkhead in the vicinity of the door
opening must be stiffened. Such bulkhead stiffeners, or deck reinforcement
where flush deck door openings are desired, must not be less than 6 inches
nor more than 12 inches from the door
frame so that an unstiffened diaphragm
of bulkhead plating 6 to 12 inches wide
is provided completely around the door
frame. Where such limits cannot be
maintained, alternative installations
will be considered by the Marine Safety
Center.
In
determining
the
scantlings of these bulkhead stiffeners,
the door frame should not be considered as contributing to the strength of
the bulkhead. Provision must also be
made to adequately support the thrust
bearings and other equipment that
may be mounted on the bulkhead or
deck.
(2) Sliding watertight door frames
must be either bolted or welded watertight to the bulkhead.
(i) If bolted, a suitable thin heat and
fire resistant gasket or suitable compound must be used between the bulkhead and the frame for watertightness.
The bulkhead plating shall be worked

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Coast Guard, DHS

§ 174.185

to a plane surface in way of the frame
when mounting.
(ii) If welded, caution must be exercised in the welding process so that the
door frame is not distorted.
[CGD 79–023, 48 FR 51048, Nov. 4, 1983, as
amended by CGD 88–032, 56 FR 35828, July 29,
1991; USCG–2000–7790, 65 FR 58464, Sept. 29,
2000]

Subpart D [Reserved]
Subpart E—Special Rules
taining to Tugboats
Towboats
§ 174.140

Perand

Specific applicability.

Each tugboat and towboat inspected
under subchapter I of this chapter
must comply with this subpart.

pmangrum on DSK3VPTVN1PROD with CFR

§ 174.145

Intact stability requirements.

(a) In each condition of loading and
operation, each vessel must be shown
by design calculations to meet the requirements of paragraphs (b) through
(e) of this section.
(b) The area under each righting arm
curve must be at least 16.9 foot-degrees
(5.15 meter-degrees) up to the smallest
of the following angles:
(1) The angle of maximum righting
arm.
(2) The downflooding angle.
(3) 40 degrees.
(c) The area under each righting arm
curve must be at least 5.6 foot-degrees
(1.72 meter-degrees) between the angles
of 30 degrees and 40 degrees, or between
30 degrees and the downflooding angle
if this angle is less than 40 degrees.
(d) The maximum righting arm shall
occur at a heel of at least 25 degrees.
(e) The righting arm curve must be
positive to at least 60 degrees.
(f) For the purpose of this section, at
each angle of heel, a vessel’s righting
arm may be calculated considering either—
(1) The vessel is permitted to trim
free until the trimming moment is
zero; or
(2) The vessel does not trim as it
heels.

Subpart G—Special Rules Pertaining to Offshore Supply
Vessels
SOURCE: CGD 82–004 and CGD 86–074, 62 FR
49353, Sept. 19, 1997, unless otherwise noted.

§ 174.180

Applicability.

Each offshore supply vessel (OSV),
except a liftboat inspected under subchapter L of this chapter, must comply
with this subpart.
§ 174.185

Intact stability.

(a) Each OSV must be shown by design calculations to meet, under each
condition of loading and operation, the
minimal requirements for metacentric
height (GM) in § 170.170 of this chapter,
and in either § 170.173 of this chapter or
paragraphs (b) through (e) of this section.
(b) The area under each righting arm
curve must be at least 0.08 meter-radians (15 foot-degrees) up to the smallest
of the following angles:
(1) The angle of maximum righting
arm;
(2) The downflooding angle; or
(3) 40 degrees.
(c) The downflooding angle must not
be less than 20 degrees.
(d) The righting arm curve must be
positive to at least 40 degrees.
(e) The freeboard at the stern must
be equal to the freeboard calculated to
comply with subchapter E of this chapter or to the value taken from Table
174.185, whichever is less.
(f) For paragraphs (b) and (d) of this
section, at each angle of heel an OSV’s
righting arm may be calculated considering either—
(1) The vessel is permitted to trim
free until the trimming moment is
zero; or
(2) The vessel does not trim as it
heels.
(g) For the purpose of paragraphs (b)
and (d) of this section, the method of
calculating righting arms chosen must
be the same for all calculations.

Subpart F [Reserved]
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§ 174.190

46 CFR Ch. I (10–1–11 Edition)

TABLE 174.185—MINIMAL FREEBOARD AT THE
STERN
Freeboard
at stern in
millimeters
(inches)

LBP in meters (feet)

Less than 20 (65) ................................................
20 (65) but less than 30 (100) ............................
30 (100) but less than 40 (130) ..........................
40 (130) but less than 50 (155) ..........................
50 (155) but less than 60 (190) ..........................
60 (190) but less than 70 (230) ..........................
70 (230) and greater ...........................................

300
380
400
500
560
610
660

(12)
(15)
(18)
(20)
(22)
(24)
(26)

§ 174.190 Collision bulkhead.
(a) Each OSV must have a collision
bulkhead
in
compliance
with
§§ 171.085(c)(1), (d), (e)(2), and (f) of this
chapter.
(b) Penetration of the collision bulkhead by piping must be minimal, and,
where fitted, piping must meet the requirements of §§ 56.50–1(b)(1) and (c) and
128.230 of this chapter.

pmangrum on DSK3VPTVN1PROD with CFR

§ 174.195 Bulkheads
in
machinery
spaces.
(a) The bulkhead in each machinery
space of each OSV must be watertight
to the bulkhead deck.
(b) Each penetration of, and each
opening in, a bulkhead in a machinery
space must—
(1) Be kept as high and as far inboard
as practicable; and
(2) Except as provided by § 174.210 of
this subpart and by paragraph (c) of
this section, have means to make it
watertight.
(c) No penetration of a bulkhead in a
machinery space by a ventilation duct
need have means to make the bulkhead
watertight if—
(1) Every part of the duct is at least
760 millimeter (30 inches) from the side
of the OSV; and
(2) The duct is continuously watertight from the penetration to the main
deck.
(d) Each penetration of a bulkhead in
a machinery space by piping must meet
the design requirements for material
and pressure in subchapter F of this
chapter.
§ 174.200 Damaged stability in machinery spaces for all OSVs.
Each OSV must be shown by design
calculations to comply, under each
afloat condition of loading and oper-

ation, with § 174.207 of this subpart in
case of damage between any two watertight bulkheads in each machinery
space.
§ 174.205 Additional damaged stability
for OSVs carrying more than 16 offshore workers.
(a) Calculations. Each OSV carrying
more than 16 offshore workers must be
shown by design calculations to comply, under each afloat condition of
loading and operation, with § 174.207 of
this subpart in case of the damage
specified by paragraph (b) of this section.
(b) Character of damage. For paragraph (a) of this section, design calculations must show that the OSV can
survive damage at any place other than
either the collision bulkhead or a
transverse watertight bulkhead unless—
(1) The transverse watertight bulkhead is closer than the longitudinal extent of damage, specified by Table
174.207(a), to the adjacent transverse
watertight bulkhead; or
(2) The transverse watertight bulkhead has a step or a recess, which must
be assumed damaged, if it is both more
than 3 meters (10 feet) in length and located within the transverse extent of
damage specified by Table 174.207(a) of
this section.
§ 174.207 Damaged stability criteria.
(a) Extent of damage. Damage must
consist of penetrations having the dimensions specified by table 174.207(a) of
this section, except that, if the most
disabling penetrations are smaller than
the penetrations specified by the table,
damage must consist of the smaller
penetrations.
(b) Permeability of spaces. The permeability of a floodable space must be as
specified by Table 174.207(b) of this section.
(c) Survival conditions. An OSV is presumed to survive assumed damage if it
meets the following conditions in the
final stage of flooding:
(1) Final waterline. The final waterline, in the final stage of sinkage, heel,
and trim, must be below the lower edge
of an opening through which progressive flooding may take place, such as
an air pipe, a tonnage opening, an

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Coast Guard, DHS

§ 174.215

opening closed by a weathertight door
or hatch-cover, or a tank vent fitted
with a ball check-valve. This opening
does not include an opening closed by
a—
(i) Watertight manhole-cover;
(ii) Flush scuttle;
(iii) Small hatch-cover for a watertight cargo-tank that maintains the
high integrity of the deck;
(iv) Watertight door in compliance
with § 174.210 of this subpart; or
(v) Side scuttle of the non-opening
type.
(2) Angle of heel. The angle of heel
must not exceed 15 degrees.
(3) Range of stability. Through an
angle of 20 degrees beyond its position
of equilibrium after flooding, an OSV
must meet the following conditions:
(i) The righting arm curve must be
positive.
(ii) The righting arm must be at least
100 millimeters (4 inches).
(iii) Each submerged opening must be
weathertight. (A tank vent fitted with
a ball check-valve is weathertight.)
(4) Progressive flooding. Piping, ducts,
or tunnels within the assumed extent
of damage must be either—
(i) Equipped with arrangements, such
as stop check-valves, to prevent progressive flooding of the spaces with
which they connect; or
(ii) Assumed in the calculations required by paragraph (a) of this section
to permit progressive flooding of the
spaces with which they connect.
(d) Buoyancy of superstructure. For
paragraph (a) of this section, the buoyancy of any superstructure directly
above the side damage must be considered in the most unfavorable condition.

pmangrum on DSK3VPTVN1PROD with CFR

TABLE 174.207(a)—EXTENT OF DAMAGE
Collision Penetration
Longitudinal extent (ves- .1L or 1.8 meters (6
sels with LBP not
feet):, whichever is
greater than 45 meters
greater in length.
[143 feet]).
Longitudinal extent (ves- 3 meters (10 feet) +
sels with LBP greater
.03L.
than 45 meters [143
feet]).
Transverse extent* ......... 760 millimeters (30
inches).

TABLE 174.207(a)—EXTENT OF DAMAGE—
Continued
Vertical extent. ................

From baseline upward
without limit.

*The transverse penetration applies inboard from the side
of the vessel, at right angles to the centerline, at the level of
the deepest load waterline.

TABLE 174.207(b)—PERMEABILITY OF SPACES
Spaces and tanks
Storerooms ............................
Accommodations ...................
Machinery ..............................
Voids and passageways ........
Dry-bulk tanks ........................
Consumable-liquid tanks .......
Other liquid tanks ...................

Permeability
60 percent.
95 percent.
85 percent.
95 percent.
0 (*) or 95 percent.
0 (*) or 95 percent.
0 (*) 0 (**) or 95 percent.

*Whichever results in the more disabling condition.
**If tanks are partly filled, the permeability must be determined from the actual density and amount of liquid carried.

§ 174.210 Watertight doors in watertight bulkheads.
(a) This section applies to each vessel
with watertight doors in bulkheads
made watertight in compliance with
this chapter.
(b) Except as provided by paragraph
(c) of this section, each watertight door
must comply with subpart H of part 170
of this chapter.
(c) A Class-1 door may be installed at
any place if—
(1) The door has a quick-acting closing-device operative from both sides of
the door;
(2) The door is designed to withstand
a head of water equivalent to the depth
from the sill of the door to the bulkhead deck or 3 meters (10 feet), whichever is greater; and
(3) The vessel’s pilothouse contains a
visual indicator showing whether the
door is open or closed.
(d) Each watertight door must be
marked in compliance with § 131.893 of
this chapter.
(e) If a Class-1 door is installed, the
vessel’s stability letter will require the
master to ensure that the door is always closed except when being used for
access.
§ 174.215

Drainage of weather deck.

The weather deck must have open
rails to allow rapid clearing of water,
or must have freeing ports in compliance with § 42.15–70 of this chapter.

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§ 174.220

46 CFR Ch. I (10–1–11 Edition)

§ 174.220 Hatches and coamings.
(a) Each hatch exposed to the weather must be watertight, except that the
following hatches may be only weathertight:
(1) Each hatch on a watertight trunk
that extends at least 430 millimeters
(17 inches) above the weather deck.
(2) Each hatch in a cabin top.
(b) Each hatch cover must—
(1) Have securing-devices; and
(2) Be attached to the hatch frame or
coaming by hinges, captive chains, or
other devices to prevent its loss.
(c) Each hatch that provides access
to quarters or to accommodation
spaces for crew members or offshore
workers must be capable of being
opened and closed from either side.
(d) Except as provided by paragraph
(e) of this section, a weathertight door
with a permanent watertight coaming
at least 380 millimeters (15 inches) high
must be installed for each opening in a
deckhouse or companionway that—
(1) Gives access into the hull; and
(2) Is in an exposed place.
(e) If an opening in a deckhouse or
companionway has a Class-1 watertight
door installed, the height of the watertight coaming need only accommodate
the door.
§ 174.225 Hull penetrations and shell
connections.
Each overboard discharge and shell
connection except an engine exhaust
must comply with §§ 56.50–95 and 128.230
of this chapter.

Subpart H—Special Rules
Pertaining to Liftboats
SOURCE: CGD 82–004 and CGD 86–074, 62 FR
49355, Sept. 19, 1997, unless otherwise noted.

§ 174.240 Applicability.
Each liftboat inspected under subchapter L of this chapter must comply
with this subpart.

pmangrum on DSK3VPTVN1PROD with CFR

§ 174.245 General.
Each liftboat must comply
§§ 174.210 through 174.225.

with

§ 174.250 Unrestricted service.
Each liftboat not limited to restricted service must comply with sub-

part C of this part in each condition of
loading and operation.
§ 174.255

Restricted service.

This section applies to each liftboat
unable to comply with § 174.250 and limited to restricted service as defined by
§ 125.160 of this chapter.
(a) Intact stability. (1) Each liftboat
must be shown by design calculations
to meet, under each condition of loading and operation afloat, the following
requirements:
(i) Those imposed by § 174.045, given a
‘‘K’’ value of at least 1.4.
(ii) A range of positive stability of at
least 10 degrees extending from the
angle of the first intercept of the
curves of righting moment and wind
heeling moment, either to the angle of
the second intercept of those curves or
to the angle of heel at which
downflooding would occur, whichever
angle is less.
(iii) A residual righting energy of at
least 0.003 meter radians (5 foot-degrees) between the angle of the first
intercept of the curves of righting moment and wind heeling moment, either
to the angle of the second intercept of
those curves or to the angle of heel at
which downflooding would occur,
whichever angle is less.
(2) For this section, each wind heeling moment must be calculated as prescribed by § 174.055 of this part using
winds of 60 knots for normal conditions
of operation afloat and of 70 knots for
severe-storm conditions of operation
afloat.
(3) For paragraph (a)(1) of this section, the initial metacentric height
must be at least 300 millimeters (1 foot)
for each leg position encountered while
afloat including the full range of leg
positions encountered while jacking.
(b) Damaged stability. (1) Each liftboat
must be designed so that, while it is in
each of its normal operating conditions, its final equilibrium waterline
will remain below the lowest edge of
any opening through which additional
flooding can occur if the liftboat is subjected simultaneously to—
(i) Damage causing flooding described by paragraph (b)(4) of this section; and

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§ 174.310

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(ii) A wind heeling moment calculated in compliance with § 174.055(b)
using a wind speed of 50 knots.
(2) Each liftboat must have a means
of closing off each pipe, ventilation
system, and trunk in each compartment described by paragraph (b)(4) of
this section if any part of the pipe, ventilation system, or trunk is within 760
millimeters (30 inches) of the hull.
(3) For compliance with paragraph
(b)(1) of this section, no compartment
on the liftboat may be ballasted or
pumped out to compensate for the
flooding described by paragraph (b)(4)
of this section.
(4) For compliance with paragraph
(b)(1) of this section, each compartment within 760 millimeters (30 inches)
of the hull, excluding the bottom of the
liftboat, between two adjacent main
watertight bulkheads and the uppermost continuous deck or first superstructure deck where superstructures
are fitted must be assumed subject to
simultaneous flooding.
(5) In the calculations required by
paragraph (b)(1) of this section, the
permeability of a floodable space must
be as listed by Table 174.205(d).
(c) On-bottom stability. Each liftboat
must be shown by design calculations
to exert a continuous downward force
on each footing when the vessel is supported on the bottom with footings and
is subjected to the forces of waves, currents, and winds of 70 knots under normal conditions of operation, and winds
of 100 knots under severe-storm conditions of operation when elevated in a
safe place, if this place is other than a
harbor of safe refuge. The waves and
currents must be appropriate for the
winds and place.
§ 174.260 Freeboard.
(a) Each liftboat not required to obtain and maintain a loadline in compliance with subchapter E of this chapter
must place markings on each side of
the vessel amidships. These markings
must each consist of a horizontal line
460 millimeters (18 inches) in length
and 25 millimeters (1 inch) in height.
The upper edges of the markings must
be at a distance equal to the authorized
freeboard measured vertically below
the intersection of the continuation
outwards of the upper surface of the

weather deck and the outer surface of
the shell. This distance must be at
least 610 millimeters (24 inches).
(b) The markings required by paragraph (a) of this section may not be
submerged in any condition of loading
or operation.

Subpart I—Hopper Dredges With
Working Freeboard Assignments
SOURCE: CGD 76–080, 54 FR 36977, Sept. 6,
1989, unless otherwise noted.

§ 174.300

Specific applicability.

This subpart applies to each self-propelled hopper dredge for which a working freeboard assignment is being
sought under part 44, subpart C, of this
chapter.
§ 174.305

Definitions.

Hopper dredge has the same meaning
as contained in § 44.310 of this chapter.
Length has the same meaning as contained in § 42.13–15(a) of this chapter.
Working freeboard has the same meaning as contained in § 44.310 of this chapter.
CALCULATIONS
§ 174.310

General.

(a) Each hopper dredge under this
subpart must be shown by design calculations based on the assumptions
under paragraphs (b), (c), (d), and (e) of
this section, that it meets—
(1) The requirements in §§ 170.170,
170.173, and 170.300 of this chapter in
each condition of loading and operation; and
(2) The survival conditions of § 174.320
in each condition of loading and operation assuming the character and extent of damage specified in § 174.315.
(b) The calculations required by paragraph (a) of this section must assume:
(1) The hoppers are full of seawater;
(2) The permeability of flooded spaces
is as provided by Table 174.310;
(3) The equalization provisions of
§ 174.325; and
(4) The jettisoning provisions of
§ 174.330.
(c) The calculations required by this
section must take into account a sufficient number of loading conditions to

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§ 174.315

46 CFR Ch. I (10–1–11 Edition)

identify the condition in which the vessel is least stable, including, but not
limited to, the most severe loading
condition, and the:
(1) Specific gravity of the dredge
spoil, from 1.02 up to and including the
maximum required by paragraph (e)(1)
of this section; and
(2) Draft, up to and including the
draft corresponding to the working
freeboard for the full range of trim.
(d) The calculations required by this
section for a dredge with open hoppers
may include spillage of spoil from the
hopper resulting from changing the
angle of heel and trim.
(e) The following assumptions must
be made when doing the calculations
required by this section:
(1) Dredged spoil in the hopper is a
homogeneous liquid with a maximum
specific gravity for the areas of operation.
(2) When calculating the vessel’s
righting arm, it is assumed at each
angle of heel that the vessel trims free
and the trimming moment is zero.
TABLE 174.310—PERMEABILITY OF FLOODABLE
SPACES
Spaces and tanks

Permeability

Storerooms ............................
Accommodation spaces ........
Consumable liquid tanks .......

Machinery space ...................

pmangrum on DSK3VPTVN1PROD with CFR

Cargo tanks ...........................

0.60
0.95
0.00 or 0.95—whichever results in the more disabling
condition.
0.85—unless otherwise supported by calculations.
Determined from the actual
density and amount of liquid carried in the tank.

§ 174.315 Extent and character of damage.
(a) The calculations required by
§ 174.310 must show that the dredge can
survive damage at any location along
the length of the vessel including at a
transverse bulkhead in accordance
with paragraph (b) of this section.
(b) The calculations required by paragraph (a) of this section must assume
the most disabling side penetration
with the damage collision penetration
provided by Table 174.315, except that if
the most disabling damage collision
penetrations would be less than those
provided by Table 174.315, the smaller
damage collision penetration must be
assumed.

TABLE 174.315—EXTENT OF DAMAGE
COLLISION PENETRATION
Longitudinal extent .........

Transverse extent 1 ........

Vertical extent .................

0.495L2/3 or 47.6 feet.
[(1⁄3)(L)2/3 or 14.5 meters] whichever is less.
B/5 or 37.7 feet. (11.5
meters), whichever is
less.
From the base line upward without limit.

1 Damage applied inboard from the vessel’s side at a right
angle to the centerline at the draft corresponding to the
working freeboard assigned under subchapter E of this
chapter.

§ 174.320

Damage survival.

A hopper dredge survives assumed
damage if it meets the following conditions:
(a) The maximum angle of heel in
each stage of flooding must not exceed
30 degrees or the angle of downflooding
whichever is less.
(b) The final waterline, taking into
account sinkage, heel, and trim, must
be below the lowest edge of each opening through which progressive flooding
may take place.
(c) The righting arm curve calculated
after damage must:
(1) Have a minimum positive range of
20 degrees beyond the angle of equilibrium; and
(2) Reach a height of at least 4 inches
(l00mm) within the 20 degree positive
range.
(d) Each opening within, or partially
within, the 20 degree range beyond the
angle of equilibrium must be weathertight.
(e) After flooding or equalization as
allowed by § 174.325, the hopper dredge’s
metacentric height must be at least 2
inches (50mm) when the dredge is in an
upright position.
§ 174.325

Equalization.

When doing the calculations required
by § 174.310 of this subpart—
(a) Equalization arrangements requiring mechanical aids, such as
valves, may not be assumed to be effective in reducing the angle of heel; and
(b) Spaces joined by ducts may be assumed to be common spaces only if
equalization takes place within 15 minutes after flooding begins.

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Coast Guard, DHS

§ 174.355

§ 174.330 Jettisoning of spoil.
(a) When doing the calculations required by § 174.310 for a hopper dredge
with bottom doors, it may be assumed
that the spoil is jettisoned immediately after damage and that the bottom doors remain open if:
(1) The bottom doors are designed so
that they may be fully opened from:
(i) The closed position within two
minutes even if the main power source
is lost or the bottom door actuating
mechanism is damaged; and
(ii) The navigating bridge;
(2) The discharge area through the
bottom doors is equal to or greater
than 30 percent of the maximum cross
sectional area of the hopper measured
in a plane parallel to the waterline;
and
(3) Asymmetrical jettisoning of the
spoil is impossible.
(b) When doing the calculations required by § 174.310 for a hopper dredge
with a split hull, it may be assumed
that the spoil is jettisoned immediately after damage if—
(1) The hull is designed so that—
(i) The complete separation is effected within two minutes even if the
main power source is lost or the actuating means is damaged; and
(ii) The actuating means can be operated from the navigating bridge;
(2) It is shown to the Commanding
Officer, Marine Safety Center, either
by calculations or by operational tests,
that the hulls can separate sufficiently
to allow the dredged material to dump
without bridging; and
(3) Asymmetrical jettisoning of the
spoil is impossible.

pmangrum on DSK3VPTVN1PROD with CFR

DESIGN
§ 174.335 Watertight doors.
(a) Each hopper dredge must have
sliding watertight doors (Class 3) approved under § 170.270 of this chapter if
the sill for the door is—
(1) Installed below the bulkhead
deck; and
(2) Less than 24 inches above the final
waterline as shown by the calculations
required by § 174.310 in each damage
condition up to and including the maximum amount of assumed damage.
(b) Each hopper dredge must have
sliding watertight doors (Class 3) ap-

proved under § 170.270 of this chapter,
or quick acting hinged watertight
doors (Class 1) approved under the
same subpart if the sill of the watertight door is—
(1) Installed below the bulkhead
deck; and
(2) Greater than 24 inches above the
final waterline as shown by the calculations required by § 174.310 in each
damage condition up to and including
the maximum amount of assumed damage.
[CGD 76–080, 54 FR 36977, Sept. 6, 1989, as
amended by CGD 95–072, 60 FR 50468, Sept. 29,
1995]

§ 174.340

Collision bulkhead.

Each hopper dredge must have a collision bulkhead that is located not less
than 5 percent of the length abaft of
the forward perpendicular.

Subpart J—Special Rules
Pertaining to Dry Cargo Ships
SOURCE: CGD 87–094, 58 FR 17320, Apr. 1,
1993, unless otherwise noted.

§ 174.350

Specific applicability.

This subpart applies to each new ship
of 500 gross tons or over, as calculated
by the International Convention on
Tonnage Measurement of Ships, 1969,
designed primarily for the carriage of
dry cargoes, including roll-on/roll-off
ships and integrated tug and barges
(ITBs) when operating as a combined
unit.
§ 174.355

Definitions.

New ship means a ship:
(1) For which the building contract is
placed on or after February 1, 1992; or
(2) In the absence of a building contract, the keel of which is laid or which
is at a similar stage of construction on
or after August 1, 1992; or
(3) The delivery of which is on or
after February 1, 1997; or
(4) For which application for reflagging is made on or after February 1,
1997; or
(5) Which has undergone a major conversion:
(i) For which the contract is placed
on or after February 1, 1992; or

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§ 174.360

46 CFR Ch. I (10–1–11 Edition)

(ii) In the absence of a contract, the
construction work of which is begun on
or after August 1, 1992; or
(iii) Which is completed on or after
February 1, 1997.

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§ 174.360 Calculations.
Each ship to which this subpart applies must comply with the minimum
standard of subdivision and damage
stability applicable to that ship under
IMO Res. MSC.216(82), (incorporated by

reference, see § 174.007). Compliance
with the applicable requirements must
be demonstrated by calculations and
reflected in information on loading restrictions, such as a maximum height
of the center of gravity (KG) or minimum metacentric height (GM) curve,
that is part of the stability information required by § 170.110 of this chapter.
[USCG–2007–0030, 75 FR 78086, Dec. 14, 2010]

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