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Title 46Chapter ISubchapter CPart 28 → Subpart E


Title 46: Shipping
PART 28—REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS


Subpart E—Stability


Contents
§28.500   Applicability.
§28.501   Substantial alterations.
§28.505   Vessel owner's responsibility.
§28.510   Definition of stability terms.
§28.515   Submergence test as an alternative to stability calculations.
§§28.520-28.525   [Reserved]
§28.530   Stability instructions.
§28.535   Inclining test.
§28.540   Free surface.
§28.545   Intact stability when using lifting gear.
§28.550   Icing.
§28.555   Freeing ports.
§28.560   Watertight and weathertight integrity.
§28.565   Water on deck.
§28.570   Intact righting energy.
§28.575   Severe wind and roll.
§28.580   Unintentional flooding.
§§28.590-28.630   [Reserved]

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§28.500   Applicability.

This subpart applies to each commercial fishing industry vessel which is 79 feet (24 meters) or more in length that is not required to be issued a load line under subchapter E of this chapter and that—

(a) Has its keel laid or is at a similar stage of construction or undergoes a major conversion started on or after September 15, 1991;

(b) Undergoes alterations to the fishing or processing equipment for the purpose of catching, landing, or processing fish in a manner different than has previously been accomplished on the vessel—these vessels need only comply with §28.501 of this subpart; or

(c) Has been substantially altered on or after September 15, 1991.

[CGD 88-079, 56 FR 40393, Aug. 14, 1991; 56 FR 47679, Sept. 20, 1991, as amended by CGD 88-079, 57 FR 364, Jan. 6, 1992]

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§28.501   Substantial alterations.

(a) Except as provided in paragraph (b) of this section, a vessel that is substantially altered, including the cumulative effects of all alterations, need not comply with the remainder of this subpart, provided that it has stability instructions developed by a qualified individual which comply with §28.530 (c) through (e).

(b) A vessel that is substantially altered in a manner which adversely affects its stability, including the cumulative effects of all alterations, need not comply with the remainder of this subpart, provided the stability instructions required by paragraph (a) of this section are based on loading conditions or operating restrictions, or both, which compensate for the adverse affects of the alterations.

(c) The following changes to a vessel's lightweight characteristics are considered to adversely affect vessel stability:

(1) An increase in the vertical center of gravity at lightweight by more than 2 inches (51 millimeters) compared to the original lightweight value.

(2) An increase or decrease of lightweight displacement by more than 3 percent of the original lightweight displacement.

(3) A shift of the longitudinal center of gravity of more than 1 percent of the vessel's length.

(d) In determining whether or not a vessel's stability has been adversely affected, a qualified individual must, at a minimum, consider the net effects on stability of any:

(1) Reduction of the downflooding angle;

(2) Increase in the maximum heeling moment caused by fishing gear or weight lifted over the side due to changes in lifting arrangement or capacity;

(3) Reduction in freeing port area;

(4) Increase in free surface effects, including increased free surface effects due to water on deck associated with any increase in length or height of bulwarks;

(5) Increase in projected wind area;

(6) Decrease in the angle of maximum righting arm;

(7) Decrease in the area under the righting arm curve; and

(8) Increase in the surface area on which ice can reasonably be expected to accumulate.

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§28.505   Vessel owner's responsibility.

(a) Where a test or calculations are necessary to evaluate stability, it is the owner's responsibility to select a qualified individual to perform the test or calculations.

(b) Test results and calculations developed in evaluating stability must be maintained by the owner.

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§28.510   Definition of stability terms.

Downflooding means 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.

Downflooding angle means the static angle from the intersection of the vessel's centerline and the waterline in calm water to the first opening that cannot be closed weathertight and through which downflooding can occur.

Flush deck means a continuous weather deck located at the uppermost sheer line of the hull.

Forward perpendicular means a vertical line corresponding to the intersection of the forward side of the vessel's stem and the vessel's waterline at the vessel's deepest operating draft.

Open boat means a vessel not protected from entry of water by means of a complete deck, or by a combination of partial weather deck and superstructure which is seaworthy for the waters upon which the vessel operates.

Protected waters means sheltered waters presenting no special hazards such as most rivers, harbors, lakes, and similar waters as determined by the OCMI.

Qualified individual means an individual or an organization with formal training in and experience in matters dealing with naval architecture calculations.

Substantially altered means the vessel is physically altered in a manner that affects the vessel's stability and includes:

(1) Alterations that result in a change of the vessel's lightweight vertical center of gravity of more than 2 inches (51 millimeters), a change in the vessel's lightweight displacement of more than 3 percent, or an increase of more than 5 percent in the vessel's projected lateral area, as determined by tests or calculations;

(2) Alterations which change the vessel's underwater shape;

(3) Alterations which change a vessel's angle of downflooding; and

(4) Alterations which change a vessel's buoyant volume.

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.

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§28.515   Submergence test as an alternative to stability calculations.

(a) A vessel may comply with this section in lieu of the remainder of the requirements in this subpart. A certification plate installed under 33 CFR part 183, subpart B, is acceptable evidence of compliance with this section.

(b) A vessel which is fitted with inboard engines and loaded as described in paragraph (e) of this section must float in calm water, after being submerged for 18 hours, so that—

(1) For an open vessel, any portion of the vessel's gunwale is above the water's surface; or

(2) For a decked vessel, any portion of the main deck is above the water's surface.

(c) A vessel which is fitted with an outboard engine must be loaded as described in paragraph (e) of this section and must float in calm water after being submerged for 18 hours so that—

(1) The vessel has an equilibrium heel angle of less than 10°;

(2) Any portion of the vessel's hull is above the water's surface; and

(3) Any portion of the lowest 3 feet (0.91 meters) of the vessel's hull is not more than 6 inches (152 millimeters) below the water's surface as measured at the lowest point on the following—

(i) The gunwale, for an open boat; or

(ii) The main deck, for a decked vessel.

(d) A vessel which is fitted with an outboard engine must be loaded as described in paragraph (f) of this section and must survive the submergence described in paragraph (c) of this section, except that the equilibrium heel angle must not exceed 30° and the vessel must float with the lower end of the vessel not more than 12 inches (0.31 meters) below the water's surface in calm water.

(e) For the tests described in paragraphs (b) and (c) of this section, a vessel must be complete in all respects, except that machinery which would be damaged by water may be replaced with equivalent fixed weight in the same location as the machinery it replaces. The vessel must be loaded with weight to represent the most adverse loading condition. The most adverse loading condition normally includes the maximum weight of fish in its highest possible location. Weights must be substituted for operating personnel at 165 pounds (734 Newtons) per individual and may be substituted for fishing gear. The substitute weights may be located transversely so that the vessel floats level prior to being submerged. The two largest air chambers, or compartments of a decked vessel not used as fuel tanks, that contribute buoyancy to the vessel must be flooded.

(f) For the test described in paragraph (d) of this section, a vessel must be complete and loaded as described in paragraph (e) of this section, except that the center of gravity of the equivalent maximum fish load must be located to one side of the vessel's centerline by a distance equal to one-fifth of the maximum transverse dimension of the fish storage space.

[CGD 88-079, 56 FR 40393, Aug. 14, 1991, as amended by USCG-2004-18884, 69 FR 58344, Sept. 30, 2004]

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§§28.520-28.525   [Reserved]

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§28.530   Stability instructions.

(a) Intent. The intent of this section is to ensure that vessel masters and individuals in charge of vessels are provided with enough stability information to allow them to maintain their vessel in a satisfactory stability condition. The rules provide maximum flexibility for owners and qualified individuals to determine how this information is conveyed, taking into consideration decisions by operating personnel must be made quickly and that few operating personnel in the commercial fishing industry have had specialized training in stability. Therefore, stability instructions should take into account the conditions a vessel may reasonably be expected to encounter and provide simple guidance for the operating personnel to deal with these situations.

(b) Each vessel must be provided with stability instructions which provide the master or individual in charge of the vessel with loading constraints and operating restrictions which maintain the vessel in a condition which meets the applicable stability requirements of this subpart.

(c) Stability instructions must be developed by a qualified individual.

(d) Stability instructions must be in a format easily understood by the master or individual in charge of the vessel. Units of measure, language, and rigor of calculations in the stability instructions must be consistent with the ability of the master or the individual in charge of the vessel. The format of the stability instructions may include, at the owner's discretion, any of the following:

(1) Simple loading instructions;

(2) A simple loading diagram with instructions;

(3) A stability booklet with sample calculations; or

(4) Any other appropriate format for providing stability instructions.

(e) Stability instructions must be developed based on the vessel's individual characteristics and may include the following, as appropriate for the format chosen for presentation:

(1) A general description of the vessel, including lightweight data;

(2) Instructions on the use of the information;

(3) General arrangement plans showing watertight compartments, closures, vents, downflooding angles, and allowable weights;

(4) Loading restrictions, such as diagrams, tables, descriptions or maximum KG curves;

(5) Sample loading conditions;

(6) General precautions for preventing unintentional flooding;

(7) Capacity plan or tank sounding tables showing tank and hold capacities, centers of gravity, and free surface effects;

(8) A rapid and simple means for evaluating any specific loading condition;

(9) The amount and location of fixed ballast;

(10) Any other necessary guidance for maintaining adequate stability under normal and emergency conditions;

(11) A general description of the stability criteria that are used in developing the instructions;

(12) Guidance on the use of roll limitation devices such as stabilizers; and

(13) Any other information the owner feels is important to the stability and operation of the vessel.

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§28.535   Inclining test.

(a) Except as provided in paragraphs (b) and (c) of this section, each vessel for which the lightweight displacement and centers of gravity must be determined in order to do the calculations required in this subpart must have an inclining test performed.

(b) A deadweight survey may be substituted for the inclining test, if there is a record of an inclining test of a sister vessel. A vessel qualifies as a sister vessel if it is built to the same basic drawings and the undocumented weight difference between the two vessels is less than 3 percent of the lightweight displacement of the vessel which was inclined and the location of the longitudinal center of gravity differs less than 1 percent of the vessel's length.

(c) A deadweight survey may be substituted for the inclining test, or the inclining test may be dispensed with, if an accurate estimate of the vessel's lightweight characteristics can be made and the precise location of the 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.

(d) ASTM F 1321 (incorporated by reference, see §28.40), with the exception of Annexes A and B, may be used as guidance for any inclining test or deadweight survey conducted under this section.

[CGD 88-079, 56 FR 40393, Aug. 14, 1991, as amended by USCG-1999-5151, 64 FR 67176, Dec. 1, 1999]

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§28.540   Free surface.

(a) When doing the stability calculations required by this subpart, the virtual rise in the vessel's vertical center of gravity due to liquids in tanks must be considered by calculating the following—

(1) For each type of consumable liquid, the maximum free surface effect of a tank, or a transverse pair of tanks, having the greatest free surface effect, in addition to a correction for service tanks; and

(2) The free surface effect of each partially filled tank and hold containing a liquid that is not a consumable or containing fish or a fish product that can shift as the vessel heels. This should include correction for any loose water within the vessel's hull associated with the processing of fish.

(b) The free surface effect of tanks fitted with cross connection piping must be calculated assuming the tanks are one common tank, unless valves that will be kept closed to prevent the transfer of liquids as the vessel heels are installed in the piping.

(c) The moment of transference method may be used in lieu of the inertia method when calculating free surface effects.

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§28.545   Intact stability when using lifting gear.

(a) Each vessel which lifts a weight over the side, or that uses fishing gear that can impose an overturning moment on the vessel, such as trawls and seines, must meet the requirements of this section if that maximum heeling moment exceeds 0.67(W)(GM)(F/B), in foot-long tons (meter-metric tons), where:

W = displacement of the vessel with the lifted weight or the force on the fishing gear included, in long tons (metric tons);

GM = metacentric height with the lifted weight or force on the fishing gear included, in feet (meters);

F = freeboard to the lowest weather deck, measured at amidships in feet (meters); and

B = maximum beam, in feet (meters).

(b) Except as provided in paragraph (f) of this section, each vessel must meet the requirements of §28.570 or have at least 15 foot-degrees (0.080 meter-radians) of area under the righting arm curve, after correcting the righting arms for the heeling arm caused by lifting or fishing gear, from the angle of equilibrium to the least of the following:

(1) The angle corresponding to the maximum righting arm;

(2) The angle of downflooding; or

(3) 40° (0.7 radians).

(c) The angle of intersection of the heeling arm curve resulting from the lifting moment or the moment of fishing gear and the righting arm curve must not be at an angle of more than 10° (0.17 radians).

(d) The heeling arm curve resulting from lifting must be calculated as the resultant of the upright heeling moment divided by the vessel's displacement multiplied by the cosine of the angle of heel.

(e) For the purposes of this section, the weight of suspended loads must be assumed to act at the tip of the boom unless the suspended load's transverse movement is restricted, such as by the use of sideboards.

(f) A vessel that operates on protected waters, as defined in §170.050 of this chapter, must comply with the requirements of this section, except that the area described in paragraph (b) of this section must be at least 10 foot-degrees (0.053 meter-radians).

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§28.550   Icing.

(a) Applicability. Each vessel that operates north of 42° North latitude between November 15 and April 15 or south of 42° South latitude between April 15 and November 15 must meet the requirements of this section.

(b) Except as provided in paragraph (d) of this section, the weight of assumed ice on each surface above the waterline of a vessel which operates north of 66°30 North latitude or south of 66° South latitude must be assumed to be at least:

(1) 6.14 pounds per square foot (30 Kilograms per square meter) of horizontal projected area which corresponds to a thickness of 1.3 inches (33 millimeters); and

(2) 3.07 pounds per square foot (15 Kilograms per square meter) of vertical projected area which corresponds to a thickness of 0.65 inches (16.5 millimeters).

(c) Except as provided in paragraph (d) of this section, the weight of assumed ice on a vessel that operates north of 42° North but south of 66°30 North latitude or south of 42° South but north of 66° South latitude must be assumed to be at least one-half of the values required by paragraphs (b)(1) and (b)(2) of this section.

(d) The height of the center of gravity of the accumulated ice should be calculated according to the position of each corresponding horizontal surface (deck and gangway) and each other continuous surface on which ice can reasonably be expected to accumulate. The projected horizontal and vertical area of each small discontinuous surface such as a rail, a spar, and rigging with no sail can be accounted for by increasing the calculated area by 15 percent.

(e) The weight and location of ice must be included in the vessel's weight and centers of gravity in each condition of loading when performing the stability calculations required by this subpart.

[CGD 88-079, 56 FR 40393, Aug. 14, 1991; 56 FR 47679, Sept. 20, 1991]

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§28.555   Freeing ports.

(a) Except as provided in paragraph (i) of this section, each decked vessel fitted with bulwarks must be fitted with freeing ports.

(b) Freeing ports must be located to allow the rapid clearing of water in all probable conditions of list and trim.

(c) Except as provided by paragraphs (d) through (h) of this section, the aggregate clear area of freeing ports on each side of the vessel must not be less than 0.71 plus 0.035 times the length of the bulwark, in meters, for area in square meters, or 7.6 plus 0.115 times the length of the bulwark, in feet, for the area in square feet. The length of bulwark need not exceed 0.7 times the overall length of the vessel.

(d) Except as provided in paragraphs (e) through (h) of this section, for bulwarks which exceed 20.11 meters (66 feet) in length, the aggregate clear area of freeing ports on each side of the vessel must not be less than 0.07 times the length of the bulwark, in meters, for an area in square meters (0.23 times the length of the bulwark in feet, for an area in square feet). The length of the bulwark need not exceed 0.7 times the overall length of the vessel.

(e) For a bulwark more than 4 feet (1.22 meters) in height, the freeing port area required by paragraphs (c) or (d) of this section must be increased in accordance with the following formula:

i = [h − 4]0.04q, (i = [h − 1.722].04q, for metric units), where:

i = increase in freeing port area, in square feet (square meters);

h = bulwark height, in feet (meters); and

q = length of bulwark exceeding 4 feet (1.22 meters) in height, in feet (meters).

(f) For a bulwark less than 3 feet (0.91 meters) in height, the required freeing port area, required by paragraph (c) or (d) of this section, may be decreased in accordance with the following formula:

r = [3 − h]0.04q, (r = [h − 0.91 − h]0.04q), where:

r = permitted reduction in freeing port area, in square feet (square meters).

h = bulwark height, in feet (meters).

q = length of bulwark which is less than 3 feet (0.914 meters) in height, in feet (meters).

(g) For a vessel without sheer, the freeing port area must be increased by 50 percent.

(h) The area of the freeing ports on a vessel that operates on protected waters need only be 50 percent of the area required by paragraphs (c) or (d) of this section.

(i) Freeing port covers are permitted provided that the freeing port area required by this section is not diminished and the covers are constructed and fitted so that water will readily flow outboard but not inboard.

[CGD 88-079, 56 FR 40393, Aug. 14, 1991, as amended by CGD 96-046, 61 FR 57276, Nov. 5, 1996]

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§28.560   Watertight and weathertight integrity.

(a) Each opening in a deck or a bulkhead that is exposed to weather must be fitted with a weathertight or a watertight closure device.

(b) Except as provided in paragraphs (c) through (f) of this section, each opening in a deck or a bulkhead that is exposed to weather must be fitted with a watertight coaming as follows:

(1) For a vessel 79 feet (24 meters) or more in length, the coaming must be at least 24 inches (0.61 meters) in height; or

(2) For a vessel less than 79 feet (24 meters) in length, the coaming must be at least 12 inches (0.30 meters) in height.

(c) A coaming to a fish hold that is under constant attention when the closure is not in place need only be 6 inches (0.15 meters) in height.

(d) The coaming of an opening fitted with a quick-acting watertight closure device need only be of sufficient height to accommodate the device.

(e) Except on an exposed forecastle deck, a coaming is not required on a deck above the lowest weather deck.

(f) Each window and portlight located below the first deck above the lowest weather deck must be provided with an inside deadlight. Each deadlight must be efficient, hinged, and arranged so that it can be effectively closed watertight.

(g) An opening in a vessel below the weather deck which is used for discharging water or debris resulting from processing or sorting operations must be fitted with a means to ensure the opening can be closed weathertight. This means of closing must be operable from a location which is outside the space containing the opening.

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§28.565   Water on deck.

(a) Each vessel with bulwarks must comply with the requirements of this section.

(b) Except for a vessel that operates on protected waters, the residual righting energy, “b” in Figure 28.565, must not be less than the water on deck heeling energy, “a” in Figure 28.565.

(c) The water on deck heeling energy must be determined assuming the following:

(1) The deck well is filled to the top of the bulwark at its lowest point and the vessel heeled to the angle at which this point is immersed;

(2) Water does not run off through the freeing ports;

(3) Vessel trim and displacement are constant and equal to the values of the vessel without the water on deck; and

(4) Water in the well is free to run-off over the top of the bulwark.

(d) The residual righting energy is the righting energy from the value where the righting arm equals the water on deck heeling arm up to the lesser of the values of 40° (0.70 radians) of heel or the downflooding angle.

eCFR graphic ec01fe91.068.gif

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§28.570   Intact righting energy.

(a) Except as provided in paragraph (c) of this section, each vessel must have the following properties in each condition of loading:

(1) An initial metacentric height (GM) of at least 1.15 feet (0.35 meters);

(2) A righting arm (GZ) of at least 0.66 feet (0.2 meters) at an angle of heel not less than 30° (0.52 radians);

(3) A maximum righting arm that occurs at an angle of heel not less than 25° (0.44 radians);

(4) An area under each righting arm curve of at least 16.9 foot-degrees (0.090 meter-radians) up to the lesser of 40° (0.70 radians) or the angle of downflooding;

(5) An area under each righting arm curve of at least 10.3 foot-degrees (0.055 meter-radians) up to an angle of heel of 30° (0.52 radians);

(6) An area under each righting arm curve of at least 5.6 foot-degrees (0.030 meter-radians) between 30° (0.52 radians) and the lesser of 40° (0.70 radians) or the angle of downflooding; and

(7) Except as provided by paragraph (b) of this section, positive righting arms through an angle of heel of 60° (1.05 radians).

(b) In lieu of meeting the requirements of paragraph (a)(7) of this section, a vessel may comply with the following provisions:

(1) Hatches in the watertight/weathertight envelope must be normally kept closed at sea (e.g., the live tank hatch is only opened intermittently, under controlled conditions); or

(2) Unintentional flooding through these hatches must not result in progressive flooding to other spaces; and

(3) In all cases, a vessel must have positive righting arms through an angle of heel of at least 50° (0.87 radians) and the intact stability analysis must consider that spaces accessed by such hatches to be flooded full or flooded to the level having the most detrimental effect on stability when free surface effects are considered.

(c) In lieu of meeting the requirements of paragraph (a) of this section, a vessel may comply with the provisions of §170.173(c) of this chapter, provided that righting arms are positive to an angle of heel of not less than 50° (0.87 radians).

(d) For the purpose of paragraphs (a) and (c) of this section, at each angle of heel a vessel's righting arm must be calculated assuming the vessel is permitted to trim free until the trimming moment is zero.

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§28.575   Severe wind and roll.

(a) Each vessel must meet paragraphs (f) and (g) of this section when subjected to the gust wind heeling arm and the angle of roll to windward as specified in this section.

(b) The gust wind heeling arm, Lw in figure 28.575 of this chapter, must be calculated by the following formula:

KEn(Vn2AnZn)/W

where:

K = 0.00216 when consistent English units are used or 1.113 when consistent metric units are used.

En = series summation notation where n varies from 1 to the number of elements in the series;

Vn = S[0.124LN(0.3048hn) + 0.772], in feet per second S[0.127LN(hn) + 0.772], in meters per second and is the wind speed for profile element “n” on a vessel;

S = 64 (19.5, if metric units are used) for a vessel that operates on protected waters; or 85.3 (26, if metric units are used) for a vessel that operates on waters other than protected waters;

LN = natural logarithm;

hn = the vertical distance from the centroid of area An to the waterline for profile element n, in feet (meters);

An = projected lateral area for profile element n, in square feet (square meters);

Zn = the vertical distance between the centroid of An and a point at the center of the underwater lateral area or a point at approximately one-half of the draft, for profile element n, in feet; and

W = displacement of the loaded vessel, in pounds (Newtons).

(c) The angle of roll to windward, A1, is measured from the equilibrium angle, Ael, and is calculated by the following formula:

A1 = 109kXY[Square root of (rs)], in degrees,

where:

s,X,Y = factors from table 28.575;

r = 0.73 + 0.6 Zg/d;

Zg = distance between the center of gravity and the waterline (+ above, − below), in feet (meters);

k = 1.0 for round bilged vessels with no bilge keels or bar keels; 0.7 for vessels with sharp bilges, or the value from table 28.575 for vessels with a bar keel, bilge keels, or both;

B = molded breadth of the vessel, in feet (meters);

d = mean molded draft of the vessel, in feet (meters);

Cb = block coefficient;

Ak = aggregate area of bilge keels, the area of the lateral projection of a bar keel, or the sum of these areas, in square feet (square meters);

L = length, in feet (meters);

T = 1.108 BC/square root of GM, in seconds; 2.0 BC/square root of GM, if metric units are used;

GM = metacentric height corrected for free surface effects, as explained in §28.540, in feet (meters);

C = 0.373 + 0.023(B/d)−0.000131L or 0.373 + 0.023(B/D)−0.00043L, if metric units are used.

(d) The angle of equilibrium, Ael in figure 28.575, is calculated by determining the lowest angle at which the gust wind heeling arm, Lw, is equal to the righting arm.

(e) The area “b” in figure 28.575 must be measured to the least of the following:

(1) The angle of downflooding, (Af);

(2) The angle of the second intercept, Ae2 in figure 28.575, of the wind heeling arm curve, Lw in figure 28.575, and the righting arm curve; or

(3) A heel angle of 50° (0.87 radians).

(f) The angle of equilibrium, Ael in figure 28.575, must not exceed 14° (0.24 radians).

(g) Area “b” in figure 28.575 must not be less than area “a” in figure 28.575.

Tables 28.575—Roll Factors

B/dX
2.41.0  
2.50.98
2.60.96
2.70.95
2.80.93
2.90.91
3.00.90
3.10.88
3.20.86
3.30.84
3.40.82
3.50.80

Note. Intermediate values must be obtained by interpolation.

CbY
0.450.75
0.500.82
0.550.89
0.600.95
0.930.97
0.701.0

Note. Intermediate values must be obtained by interpolation.

100Ak/(LB)k
01.0
1.00.98
1.50.95
2.00.88
2.50.79
3.00.74
3.50.72
4.00.70

Note. Intermediate values must be obtained by interpolation.

TS
  60.100
  70.098
  80.093
120.065
140.053
160.044
180.038
200.035

Note: Intermediate values must be obtained by interpolation.

eCFR graphic er29se08.000.gif

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[56 FR 40393, Aug. 14, 1991, CGD 88-079; 56 FR 47679, Sept. 20, 1991, CGD 88-079, as amended by CGD 95-072, 60 FR 50461, Sept. 29, 1995; USCG-2004-18884, 69 FR 58344, Sept. 30, 2004; USCG-2008-0906, 73 FR 56509, Sept. 29, 2008]

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§28.580   Unintentional flooding.

(a) Applicability. Except for an open boat that operates on protected waters and as provided by paragraph (i) of this section, each vessel built on or after September 15, 1991 must comply with the requirements of this section.

(b) Collision bulkhead. A watertight collision bulkhead must be fitted and must meet the following:

(1) Openings in the collision bulkhead must be kept to a minimum, and each must be fitted with a watertight closure device;

(2) A collision bulkhead must not be fitted with a door below the bulkhead deck;

(3) A penetration or opening in a collision bulkhead must be—

(i) Located as high and as far inboard as practicable; and

(ii) Fitted with a means to rapidly make it watertight which is operable from a location aft of the collision bulkhead;

(4) The collision bulkhead must be located at least 5 percent of the length from the forward perpendicular unless the vessel has a bulbous bow, in which case the forward reference point will be extended by half the distance between the vessel's forward perpendicular and the forwardmost point of the bulbous bow as shown in figure 28.580; and

(5) The collision bulkhead must not be stepped below the bulkhead deck.

(c) Each vessel must meet the survival conditions in paragraph (f) of this section in each condition of loading and operation with the extent and character of damage specified in paragraphs (d) and (e) of this section.

(d) Extent and character of damage. Except where a lesser extent of damage or a smaller penetration would be more disabling, in evaluating the damage stability of a vessel the following penetration must be assumed:

(1) Longitudinal extent—L/10, or 10 feet (3.05 meters) plus 0.03L, whichever is less. Transverse watertight bulkheads that are separated by at least this distance may be assumed to remain effective;

(2) Transverse extent—30 inches (0.76 meters) from the side measured at right angles to the centerline at the level of the deepest operating waterline; and

(3) Vertical extent—from the baseline upward without limit.

(e) Each space containing a through hull fitting, such as the lazarette and the engineroom, must be assumed to be flooded.

(f) Survival conditions. A vessel is presumed to survive the assumed damage and unintentional flooding described in paragraphs (d) and (e) of this section if:

(1) The angle of equilibrium after flooding does not exceed 25° (0.44 radians); and

(2) Through an angle of 20° (0.35 radians) beyond the angle of equilibrium after flooding, the following are met—

(i) The righting arm curve is positive;

(ii) The maximum righting arm is at least 4 inches (102 millimeters);

(iii) Each submerged opening is capable of being made weathertight; and

(iv) The heeling arm caused by deploying all fully loaded davit-launched survival craft on one side of a vessel does not exceed the righting arm at any angle of heel beyond the equilibrium angle when launching is assumed on the damaged side.

(g) Permeability. The permeability of each space must not be less than the following:

(1) For an accommodations space—95 percent;

(2) For a propulsion machinery space—85 percent;

(3) For a tightly packed storage space—60 percent;

(4) For a void or an auxiliary machinery space—95 percent;

(5) For an empty fish hold—95 percent;

(6) For a full fish hold—50 percent; and

(7) For tanks—95 percent (less if a tank must be full to attain the draft under consideration.)

(h) Buoyancy of superstructure. A deckhouse or a superstructure may be included in the buoyant volume of a vessel provided it is:

(1) Sufficiently strong to withstand the impact of waves;

(2) Fitted with a weathertight or watertight closure device for each opening;

(3) Equipped with an efficient, hinged, inside deadlight, for each window and each portlight, arranged so that it can be effectively closed watertight; and

(4) Fitted with interior access from the spaces below.

(i) A vessel may obtain and maintain a Load Line Certificate under subchapter E of this chapter in lieu of meeting the requirements of paragraphs (c) through (g) of this section.

eCFR graphic ec01fe91.070.gif

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[CGD 88-079, 56 FR 40393, Aug. 14, 1991; 56 FR 47679, Sept. 20, 1991, as amended by CGD 88-079, 57 FR 364, Jan. 6, 1992]

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§§28.590-28.630   [Reserved]

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