((a)) When the application of a law of the United States to a vessel depends on the vessel’s tonnage, the vessel shall be measured under this part.

((b)) If a statute allows for an alternate tonnage to be prescribed under this section, the Secretary may prescribe it by regulation. Any such regulation shall be considered to be an interpretive regulation for purposes of . Until an alternate tonnage is prescribed, the statutorily established tonnage shall apply to vessels measured under chapter 143 or chapter 145 of this title.

((c)) The head of each Federal agency shall ensure that regulations issued by the agency that specify particular tonnages comply with the alternate tonnages implemented by the Secretary.