State registration number and certificate of number

Registration & documentation · Power & sail

Any boat with an engine of any kind used on US waters, including a sailboat with an auxiliary, needs a state-issued number and a certificate of number aboard, unless it is Coast Guard documented. Your state runs the system within federal rules (33 CFR 173.11, 173.15, 173.21).

Which boats must be numbered

• Federal numbering covers every vessel fitted with propulsion machinery of any type that is used on US waters, plus US-owned boats on the high seas. A sailboat with an outboard or inboard counts (33 CFR 173.11).
• A boat that has, or is required to have, Coast Guard documentation is outside the numbering rules (33 CFR 173.11(e)).
• You number the boat in its 'state of principal operation', the state whose waters you use most during a calendar year (33 CFR 173.3, 173.15).
• Every state now runs its own approved numbering system, so you apply to your state boating agency, which sets the fee and the application process (33 CFR 173.71; 33 CFR 173 appendix A).
• States may go beyond the federal minimum, for example by numbering boats without engines, or by requiring a title, proof of insurance or proof of taxes paid before they issue a number (33 CFR 174.11(b), 174.31).

The certificate aboard

• Whoever is operating must have the valid certificate of number, or a temporary certificate from the state, aboard and must hand it to any federal, state or local law enforcement officer who asks to see it (33 CFR 173.21, 173.23, 173.25).
• Since July 5, 2024 the federal rules let you carry the certificate in hard copy or digital form, following a 2022 change to the law (33 CFR 173.21(a); 46 U.S.C. 12304(a)). Check how your state issues and accepts a digital version.
• If the certificate is lost or destroyed, tell the state and apply for a duplicate (33 CFR 173.29(c), 173.71(c)).

How long it lasts, and other states

• Your state sets the expiration date, but federal rules cap any certificate of number at 3 years (33 CFR 173.77(a), 174.27; 46 U.S.C. 12304(a)).
• A boat numbered in one state is treated as compliant while it is temporarily operated in another state (33 CFR 173.17(a); 46 U.S.C. 12302(c)).
• If the boat's state of principal operation changes, the new state must recognise your old number for 60 days, and the old certificate becomes invalid 60 days after the boat stops being principally operated in the issuing state (33 CFR 173.17(b), 173.77(d)).
• The certificate also becomes invalid when the boat is documented, when you transfer all your ownership, when the boat is destroyed or abandoned, if the application was false or the fees unpaid, or if you lose the boat through legal process (33 CFR 173.77).

What to tell the state, and how fast

• Within 15 days, the owner named on the certificate must notify the state, in the way the state prescribes, of: a change of address; theft or recovery of the boat; loss or destruction of the certificate; transfer of all or part of the owner's interest; destruction or abandonment of the boat (33 CFR 173.29).
• When the certificate becomes invalid, for example after a sale, documentation or the boat's destruction, the owner must surrender it as the state directs (33 CFR 173.31).
• Remove the number and the validation decal from the boat when it is documented, when the certificate is invalid because of a false application or unpaid fees, or when the boat is no longer principally operated in that state (33 CFR 173.33).

The rules: 33 CFR 173.3 · 33 CFR 173.11 · 33 CFR 173.15 · 33 CFR 173.17 · 33 CFR 173.21 · 33 CFR 173.23 · 33 CFR 173.25 · 33 CFR 173.29 · 33 CFR 173.31 · 33 CFR 173.33 · 33 CFR 173.71 · 33 CFR 173.77 · 33 CFR 174.11 · 33 CFR 174.27 · 33 CFR 174.31 · 46 U.S.C. 12302 · 46 U.S.C. 12304

A plain-language summary of federal rules for recreational boats, checked against the rules’ own text and a second source, and written in our own words. It isn’t legal advice. States add rules of their own, and rules change — the links above go to the current official text.