46 U.S.C. § 12502: Identification numbers, signal letters, and markings

(a) For the identification of a vessel of the United States, the Secretary of Transportation—(1) shall maintain a unique numbering system and assign a number to each vessel of the United States; (2) may maintain a system of signal letters for a documented vessel; (3) shall record a name selected by the owner of a documented vessel approved by the Secretary as the vessel’s name of record; and (4) may establish other identification markings. (b) The manufacturer or owner of a vessel shall affix to the vessel and maintain in the manner prescribed by the Secretary the number assigned and any other markings the Secretary may require. (c) Once a number is assigned under this section, it may not be used by another vessel. (d) Once a documented vessel’s name is established, the name may not be changed without the approval of the Secretary. (e) A person may not tamper with or falsify a number or other marking required under this section.