Code of Federal Regulations Title 46. Shipping § 46.172.150 Survival conditions

(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:

(b) Heel angle.

(c) Range of stability. Through an angle of 20 degrees beyond its position of equilibrium after flooding, a tankship must meet the following conditions:

(d) Progressive flooding. Pipes, ducts or tunnels within the assumed extent of damage must be either—

(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 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.