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

(a) To identify U.S. vessels, the Secretary of Transportation must keep a numbering system and give each U.S. vessel its own number. The Secretary may also keep a system of signal letters for a "documented" vessel — one formally registered with the government. The Secretary must record the name the owner picked for a documented vessel, once the Secretary approves it, as that vessel's official name of record. The Secretary may also set up other kinds of identification markings. (b) The person who built or owns the vessel must attach the assigned number, and any other required markings, to the vessel, and keep them there, following the rules the Secretary sets. (c) Once a number is given to a vessel, no other vessel may use that same number. (d) Once a documented vessel's name is on record, it can't be changed unless the Secretary approves the change. (e) No one may tamper with or fake a number or other marking required by this section.