Title 46

SECTION 174.207

174.207 Damaged stability criteria.

§ 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 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.

Table 174.207(a) - Extent of Damage

Collision Penetration
Longitudinal extent (vessels with LBP not greater than 45 meters [143 feet])	.1L or 1.8 meters (6 feet), whichever is greater in length.
Longitudinal extent (vessels with LBP greater than 45 meters [143 feet])	3 meters (10 feet) + .03L.
Transverse extent*	760 millimeters (30 inches).
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	Permeability
Storerooms	60 percent.
Accommodations	95 percent.
Machinery	85 percent.
Voids and passageways	95 percent.
Dry-bulk tanks	0 (*) or 95 percent.
Consumable-liquid tanks	0 (*) or 95 percent.
Other liquid tanks	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.