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

shall maintain a unique numbering system and assign a number to each vessel of the United States; may maintain a system of signal letters for a documented vessel; shall record a name selected by the owner of a documented vessel approved by the Secretary as the vessel’s name of record; and may establish other identification markings. 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. Once a number is assigned under this section, it may not be used by another vessel. Once a documented vessel’s name is established, the name may not be changed without the approval of the Secretary. A person may not tamper with or falsify a number or other marking required under this section. the next time the vessel is documented, numbered, or titled. January 1, 1995 .”