46 CFR §170.200

1. (a)Each tank vessel that does not carry a material listed in either Table 1 of part 153 or Table 4 of part 154 of this chapter may comply with this section in lieu of § 170.175 if it—
   1. (1)Is 150 gross tons or greater;
   2. (2)Is of ordinary proportions and form;
   3. (3)Has a flush weather deck, one or more longitudinal bulkheads, and no independent tanks; and
   4. (4)Is designed not to carry cargo above the freeboard deck.
2. (b)When doing the calculations required by §§ 170.170 and 172.065, the vertical center of gravity of a tank vessel in the lightweight condition must be assumed to be equal to the following percentage of the molded depth of the vessel measured from the keel amidship:
   1. (1)For a tank ship—70%.
   2. (2)For a tank barge—60%.
3. (c)As used in this section, molded depth has the same meaning that is provided for the term in § 42.13-15(e) of this chapter.