46 U.S.C. § 53901: Definitions

a documented vessel with a registry or coastwise endorsement under chapter 121 of this title; an undocumented vessel owned or chartered by or made available to the United States Government; and a tug, barge, or other watercraft (whether or not documented) owned by a citizen of the United States and used in essential water transportation or in the fisheries, except only for sport fishing. The term “cargo” includes a loaded or empty container on a vessel. The term “transportation in the waterborne commerce of the United States” includes the operation of a vessel in the fisheries, except only for sport fishing. any part of a loss excluded from marine insurance coverage under a “free of capture or seizure” clause or analogous clause; and any other loss from a hostile act, including confiscation, expropriation, nationalization, or deprivation.