[Code of Federal Regulations]
[Title 46, Volume 7]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR171.080]
[Page 131-135]
TITLE 46--SHIPPING
CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
PART 171_SPECIAL RULES PERTAINING TO VESSELS CARRYING PASSENGERS--Table
of Contents
Subpart C_Large Vessels
Sec. 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
[[Page 132]]
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.
(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.
[[Page 133]]
(1) Each vessel must have positive righting arms for a minimum range
beyond the angle of equilibrium as follows:
------------------------------------------------------------------------
Required
Vessel service range
(degrees)
------------------------------------------------------------------------
Exposed waters, oceans, or Great Lakes winter................ 15
Partially protected waters or Great Lakes summer............. 10
Protected waters............................................. 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:
[GRAPHIC] [TIFF OMITTED] TR17OC95.004
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;
[Delta]=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)
where--
n=number of passengers;
w=passenger weight = 75 kilograms; 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.
(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) Each passenger weighs 75 kilograms;
(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 one-half 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;
[[Page 134]]
(ii) 12 degrees for flooding of two compartments; or
(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([thetas]-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.
[thetas]=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 Required
Vessel service range maximum
(degrees) righting arm
------------------------------------------------------------------------
Exposed waters, oceans, or Great Lakes winter 7 0.05 m
Partially-protected waters or Great Lakes 5 0.035 m
summer......................................
Protected waters............................. 5 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 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, chapter II-1, part B, regulation 8.
(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 mf heel before equalization must be
approved by the Commanding Officer, Marine Safety Center.
Table 171.080(a)--Extent and Character of Damage
----------------------------------------------------------------------------------------------------------------
Vessel designator Longitudinal Transverse penetration
1 penetration 2 3, 4 Vertical penetration Character of Damage
----------------------------------------------------------------------------------------------------------------
Z................ 10 feet (3 meters) B/5................... from the baseline Assumes no damage to
plus ).03L or 35 feet upward without limit. any main transverse
(10.7 meters) watertight bulkhead.
whichever is less.5
Y................ 10 feet (3 meters) B/5................... From the baseline Assumes damage to no
plus )0.03L or 35 upward without limit. more than one main
feet (10.7 meters) transverse
whichever is less. watertight bulkhead.
X................ 10 feet (3 meters) B/5................... from the baseline Assumes damage to no
plus )0.03L or 35 upward without limit. more than one main
feet (10.7 meters transverse
whichever is less. watertight bulkhead.
20 feet (6.1 meters) B/5................... From the top of the Assumes damage to no
plus 0.04L. double bottom upward more than one main
without limit. transverse
watertight bulkhead.
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W................ 20 feet (6.1 meters) B/5................... From the baseline Assumes damage to at
plus 0.04L. upward without limit. 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 Sec. 171.070(e)(2).
Table 171.080(b)
------------------------------------------------------------------------
Vessel category Vessel designator
------------------------------------------------------------------------
Vessels with type I subdivision and a factor W.
of subdivision as determined from Sec.
171.065 (a) or (b) of 0.33 or less.
Vessels with type I subdivision and a factor X.
of subdivision as determined from Sec.
171.065 (a) or (b) greater than 0.33 and
less than or equal to 0.50.
Vessels with Type II subdivision that are Y.
required to meet a two compartment standard
of flooding.
All other vessels........................... Z.
------------------------------------------------------------------------
Table 171.080(c)--Permeability
------------------------------------------------------------------------
Spaces and tanks Permeability (percent
------------------------------------------------------------------------
Cargo, coal, stores........................ 60.
Accommodations............................. 95.
Machinery.................................. 85.
Tanks...................................... o or 95.\1\
------------------------------------------------------------------------
\1\ Whichever 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]