19 CFR § 4.0 - General definitions.
For the purposes of this part:
(a) Vessel. The word vessel includes every description of water craft or other contrivance used or capable of being used as a means of transportation on water, but does not include aircraft. (19 U.S.C. 1401.)
(b) Vessel of the United States. The term vessel of the United States means any vessel documented under the laws of the United States.
(c) Documented. The term documented vessel means a vessel for which a valid Certificate of Documentation, form CG 1270, issued by the U.S. Coast Guard is outstanding. Upon qualification and proper application to the appropriate Coast Guard office, the Certificate of Documentation may be endorsed with a: (1) Registry endorsement (generally, available to a vessel to be employed in foreign trade, trade with Guam, American Samoa, Wake, Midway, or Kingman Reef, and other employments for which another endorsement is not required), (2) coastwise endorsement (generally, entitles a vessel to employment in the coastwise trade, and other employments for which another endorsement is not required), (3) fishery endorsement (generally, subject to federal and state laws regulating the fisheries, entitles a vessel to fish within the Exclusive Economic Zone (16 U.S.C. 1811) and landward of that zone and to land its catch) or (4) recreational endorsement (entitles a vessel to recreational use only). Any other terminology used elsewhere in this part to describe the particular documentation of a vessel shall be read as synonymous with the applicable terminology contained in this paragraph. Generally, any vessel of at least 5 net tons and wholly owned by a United States citizen or citizens is eligible for documentation except that for a coastwise, or fisheries endorsement a vessel must also be built in the United States. Detailed Coast Guard regulations on documentation are set forth in Title 46, Code of Federal Regulations, § 67.01-67.45.
(d) Noncontiguous territory of the United States. The term noncontiguous territory of the United States includes all the island territories and possessions of the United States, but does not include the Canal Zone.
(f) Arrival of a vessel. The phrase “arrival of a vessel” means that time when the vessel first comes to rest, whether at anchor or at a dock, in any harbor within the Customs territory of the U.S.
(g) Departure of a vessel. The phrase “departure of a vessel” means that time when the vessel gets under way on its outward voyage and proceeds on the voyage without thereafter coming to rest in the harbor from which it is going.