46 CFR § 125.115 - Oil fuel tank protection.
(a) An OSV of at least 6,000 GT ITC (500 GRT if GT ITC is not assigned) that is delivered after August 1, 2010, with an aggregate capacity of 600 cubic meters or more of oil fuel, must comply with the requirements of Regulation 12A of Annex I to MARPOL 73/78 (incorporated by reference, see § 125.180) at all times.
(b) Transfer of excess fuel oil from the fuel supply tanks of an OSV of at least 6,000 GT ITC (500 GRT if GT ITC is not assigned) to an offshore drilling or production facility will not cause Subchapter D of this chapter to apply to the OSV, provided that the vessel is -
(1) Not a tankship as defined in 46 CFR 30.10-67; and
(2) In the service of oil exploitation.