StatA

Coast Guard, DHS

§ 31.10–21

(b) Internal structural examination
means an examination of the vessel
while afloat or in drydock and consists
of a complete examination of the vessel’s main strength members, including
the major internal framing, the hull
plating, voids, and ballast tanks, but
not including cargo or fuel oil tanks.
(c) Cargo tank internal examination
means an examination of the vessel
while afloat or in drydock and consists
of an examination of the internals of
all cargo tanks; except, if the vessel is
certificated to carry cargoes regulated
under part 38 or subchapter O of this
chapter, the cargo tank internal examination must be accomplished as specified in parts 38 and 151 of this chapter
respectively.
(d) Underwater survey means the examination, while the vessel is afloat, of
all accessible parts of the vessel’s un-

derwater body and all through-hull fittings.
[CGD 84–024, 52 FR 39649, Oct. 23, 1987, as
amended by CGD 84–024, 53 FR 32229, Aug. 24,
1988; CGD 95–028, 62 FR 51197, Sept. 30, 1997]

§ 31.10–21 Drydock examination, internal structural examination, cargo
tank internal examination, and underwater survey intervals—TB/ALL.
(a) Except as provided in paragraphs
(b) through (g) of this section, each
tank vessel must undergo drydock, internal structural, and cargo tank internal examinations as follows:
(1) Except under paragraph (a)(2) of
this section, vessels that operate in
salt water must be inspected in accordance with the intervals set forth in
table 31.10–21(a). Where table 31.10–21(a)
indicates a 2.5 year examination interval, it means a vessel must undergo
two examinations within any five year
period. No more than three years may
elapse between any two examinations.

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§ 31.10–21

46 CFR Ch. I (10–1–12 Edition)

(2) Vessels that operate in fresh
water at least six months in every 12
month period since the last drydock
examination must be examined in ac-

cordance with the intervals set forth in
table 31.10–21(b). Where table 31.10–21(b)
indicates a 2.5 year examination interval, it means a vessel must undergo

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382

Coast Guard, DHS

§ 31.10–21

two examinations within any five year
period. No more than three years may
elapse between any two examinations.

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383

§ 31.10–21a

46 CFR Ch. I (10–1–12 Edition)

(b) During each inspection or reinspection for certification, all wing
voids, rakes, cofferdams, and other
void spaces on tank barges must be
opened and checked from on-deck for
the presence of water or cargo indicating hull damage or cargo tank leakage. If water or cargo is not present,
these spaces need not be gas freed, ventilated, cleaned, or otherwise prepared
for personnel entry. If water or cargo is
present, an internal structural examination may be required.
(c) If, during an internal structural
examination, cargo tank internal examination, or underwater survey, damage or deterioration to the hull plating, structural members, or cargo
tanks is discovered, the Officer in
Charge, Marine Inspection, may require the vessel to be drydocked or otherwise taken out of service to further
assess the extent of the damage and to
effect permanent repairs.
(d) Vessels less than 15 years of age
(except wooden hull vessels) that are in
salt water service with a 2.5 year drydock interval (as indicated in table
31.10–21(a) of this section) or that are in
fresh water service with a five year
drydock interval (as indicated in table
31.10–21(b) of this section) may be considered for an underwater survey instead of alternate drydock examinations, provided the vessel is fitted with
an effective hull protection system.
Vessel owners or operators must apply
to the Officer in Charge, Marine Inspection, for approval of underwater
surveys instead of alternate drydock
examinations for each vessel. The application must include the following
information:
(1) The procedure to be followed in
carrying out the underwater survey.
(2) The location where the underwater survey will be accomplished.
(3) The method to be used to accurately determine the diver location relative to the hull.
(4) The means that will be provided
for examining through-hull fittings.
(5) The means that will be provided
for taking shaft bearing clearances.
(6) The condition of the vessel, including the anticipated draft of the
vessel at the time of the survey.
(7) A description of the hull protection system.

(e) Vessels otherwise qualifying
under paragraph (d) of this section,
that are 15 years of age or older may be
considered for continued participation
in or entry into the underwater survey
program on a case-by-case basis, if—
(1) Before the vessel’s next scheduled
drydocking, the owner or operator submits a request for participation or continued participation to Commandant
(CG–CVC);
(2)
During
the
vessel’s
next
drydocking after the request is submitted, no appreciable hull deterioration is indicated as a result of a complete set of hull gaugings; and
(3) The results of the hull gauging
and the results of the Coast Guard drydock examination together with the
recommendation of the Officer in
Charge, Marine Inspection, are submitted to Commandant (CG–CVC) for
final approval.
(f) Each vessel which has not met
with the applicable examination schedules in paragraphs (a) through (e) of
this section because it is on a voyage,
must undergo the required examinations upon completion of the voyage.
(g) The Commandant (CG–CVC) may
authorize extensions to the examination intervals specified in paragraph
(a) of this section.
[CGD 84–024, 52 FR 39649, Oct. 23, 1987, as
amended at 53 FR 32230, Aug. 24, 1988; 53 FR
34872, Sept. 8, 1988; CGD 95–072, 60 FR 50461,
Sept. 29, 1995; CGD 91–045, 61 FR 39792, July
30, 1996; CGD 96–041, 61 FR 50726, Sept. 27,
1996; CGD 95–028, 62 FR 51198, Sept. 30, 1997;
USCG–2009–0702, 74 FR 49226, Sept. 25, 2009]

§ 31.10–21a Periodic gauging of tank
vessel midbodies more than 30
years old that carry certain oil cargoes—TB/ALL.
(a) As used in this section, the term
‘‘midbody’’ means the 40-percent midship length (0.40L) of the tank vessel.
The age of the midbody is determined
from its year of original construction.
(b) Midbodies of all tank vessels certificated to carry a pollution category
I oil cargo listed in 46 CFR Table 30.25–
1 must undergo an initial gauging survey and periodic regauging surveys as
follows:
(1) An initial midbody gauging survey must be accomplished no later
than the next drydocking inspection

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