46 CFR §172.110

1. (a)Paragraphs (c) and (d) of this section apply to a hopper barge and paragraphs (e) through (i) apply to all other tank barges.
2. (b)A barge is presumed to survive assumed damage if it meets the following conditions in the final stage of flooding:
3. (c)A hopper barge must not heel or trim beyond the angle at which—
   1. (1)The deck edge is first submerged; or
   2. (2)If the barge has a coaming that is at least 36 inches (91.5 centimeters) in height, the intersection of the deck and the coaming is first submerged, except as provided in paragraph (d) of this section.
4. (d)A hopper barge must not heel beyond the angle at which the deck edge is first submerged by more than “fa” as defined in § 172.090(c).
5. (e)Except as provided in paragraphs (h) and (i) of this section, each tank barge must not heel beyond the angle at which—
   1. (1)The deck edge is first submerged; or
   2. (2)If the barge has one or more watertight trunks, the deck edge is first submerged by more than “fa” as defined in § 172.090(c).
6. (f)Except as provided in paragraphs (h) and (i) of this section, a tank barge must not trim beyond the angle at which—
   1. (1)The deck edge is first submerged; or
   2. (2)If the barge has one or more watertight trunks, the intersection of the deck and the trunk is first submerged.
7. (g)If a tank barge experiences simultaneous heel and trim, the trim requirements in paragraph (f) of this section apply only at the centerline.
8. (h)Except as provided in paragraph (i) of this section, in no case may any part of the actual cargo tank top be underwater in the final condition of equilibrium.
9. (i)If a barge has a “step-down” in hull depth on either or both ends and all cargo tank openings are located on the higher deck level, the deck edge and tank top in the stepped-down area may be submerged.