Boat Registration Numbers: Size, Spacing and Placement Rules
How boat registration numbers must be displayed: the federal 3 inch rule, spacing, and where states differ, plus what our lettering can and cannot do.
Boat registration numbers are lettering with rules. The federal rule sets the size and spacing of the characters, and your state sets where they go and which stickers go with them. This page explains what the rules say and, plainly, what our lettering can and cannot do for a hull. It is a summary: check your own state's boating agency before you apply anything to a boat.
What the federal rule says
The Coast Guard rule for state-numbered boats is in 33 CFR 173.27. In plain words:
- The number goes on both sides of the forward half of the boat.
- The characters are plain vertical block letters and numbers, at least 3 inches tall.
- They are a color that contrasts with the hull and read from left to right.
- A space or a hyphen separates the letter groups from the number groups, about as wide as a letter.
The rule is written for the number itself. It does not say how to attach it, so placement details come from your state.
How states differ
States add their own details, usually about the validation sticker and distances. Examples we confirmed from state agencies:
- California asks for the decal about 3 inches from the number.
- Florida places the decal on the port side within 6 inches of the number.
- Texas asks for the decal 3 inches aft of the number, in line with it.
- Wisconsin has different decal positions for documented boats.
Other states differ too. Use your own state's boating agency page, and do not copy a neighbor's layout.
Documented boats are different
A boat documented with the Coast Guard follows other lettering rules. The vessel name and hailing port are marked in letters at least 4 inches high (46 CFR 67.123), and the official number is marked inside the hull (46 CFR 67.121). Many states still ask a documented boat to carry a state decal.
What our lettering can do for a boat
Honest answer, so you do not order the wrong thing: our standard decals are up to 24 inches wide. A typical registration number of about ten characters, such as a two letter prefix, four digits and two letters with spaces, fills that width with letters about 2 inches tall. That is under the 3 inch minimum the federal rule asks for. Because of that, we do not recommend our standard decals for the registration number on a hull.
What they are good for: boat names and other decorative or informational lettering where no regulation sets the size, and the numbers and lettering on a trailer, a dock box or a tow vehicle. If you need full-size 3 inch registration characters, contact us with your number and the length you need and we will tell you what we can make.
Before you buy lettering for a boat
- We make the lettering, not the number or the sticker. The number and the validation decal come from your state.
- Check the vinyl for your use. Our vinyl is outdoor sign vinyl made for vehicles. We have not tested it for marine use, saltwater or immersion, so we do not claim it. Ask us if you are unsure.
- Hull numbers are not registration numbers. The long identification number the builder stamps on the hull (the HIN) is a different thing.
- Nothing here is legal advice. Boat rules are set by your state and the Coast Guard, and they change.
Sources
Frequently asked questions
How tall do boat registration numbers need to be?
At least 3 inches, in plain block characters, according to 33 CFR 173.27. California words it as more than 3 inches in some state materials, so leave a little margin.
Where does the number go?
On both sides of the forward half of the boat. Your state tells you where the validation decal goes in relation to it.
Can you make 3 inch registration numbers?
Our standard decals top out at 24 inches wide, which is not enough for a typical number at 3 inch height. Contact us with your number and we will say what we can do.
Is the number the same as the HIN?
No. The HIN is stamped by the builder. The registration number is issued by your state.
Do you sell the validation sticker?
No. The sticker is issued by your state.
Checked 2026-10-13. Rules change, so confirm with your agency.
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