Boat Registration Number Rules, Plainly Stated
The federal rule, in full. Under 33 CFR 173.27, a registration number must:
- be painted on or permanently attached to each side of the forward half of the vessel;
- be in plain vertical block characters of not less than 3 inches in height;
- contrast with the colour of the background and be distinctly visible and legible;
- have spaces or hyphens between the letter and number groupings equal to the width of a letter other than “I” or a number other than “1” — so TX 1234 AB, not TX1234AB;
- read from left to right.
Why it is one rule and not fifty
Boat numbering comes from the Federal Boat Safety Act, and states administer it under a federally approved numbering system. That is why the core requirements are identical from Florida to Alaska: a state can add requirements, but it cannot issue you a number and then let you display it smaller than 3 inches.
So when a shop tells you “your state is different,” what they almost always mean is one of three things: your prefix, your issuing agency, or where the validation decal goes.
The rule most people miss is contrast. There is no required colour — but white numbers on a white hull are not “distinctly visible and legible,” and that is a failed inspection. Dark hull, light numbers. Light hull, dark numbers. Our order form flags the combination before it gets cut.
The five failures we see
- Characters under 3 inches. Usually because someone bought a set sized to fit a small panel instead of sizing the panel to the rule.
- No contrast. White on white, or a dark navy on black.
- No spacing. TX1234AB run together, because that is how it looks on some registration cards.
- Script or outline fonts. The rule says plain vertical block. An outline font with a hollow centre is not plain block.
- Too far aft. They have to be on the forward half. Numbers on the stern quarter are a common and easily avoided ticket.
What about documented vessels?
Different rules entirely. A USCG documented vessel does not display state registration numbers at all — it carries its name and hailing port in 4-inch characters instead. See our documented vessel guide.
Ready to order?
$19 a pair, free shipping, cut and shipped the next business day. The preview shows your exact lettering before you pay.
Questions people actually ask
How big do boat registration numbers have to be?
At least 3 inches tall. Federal rule 33 CFR 173.27 sets 3 inches as the minimum for the block characters on the bow, and every state adopts that floor. Nothing stops you going bigger, and a few owners do for readability.
What font is legal for boat registration numbers?
Plain vertical block characters. Script, italic, outline and heavily stylised faces are not legal for the registration number, because 33 CFR 173.27 requires plain block letters that read clearly at a distance. A boat name on the transom has no such rule, so script is fine there.
Do boat registration numbers have to be a certain colour?
No specific colour, but they must contrast with the hull. The rule says the characters must be of a colour that contrasts with the background so they are distinctly visible - white on a dark hull, black on a light one. White on cream is the common failure.
Do I need spaces or hyphens between the number groups?
Yes - the prefix, the digits and the suffix must be separated by a space or a hyphen equal to the width of a letter. IA 3717 ZW, not IA3717ZW.
Where do the registration numbers go on a boat?
On the forward half of both sides of the hull, reading left to right. The validation decal goes within six inches of the number, which side and which end depends on your state.
Are boat registration number rules the same in every state?
The display rules are federal and identical in all 50 states. The number FORMAT differs: the two-letter vessel prefix is not always the postal code, and a few states allow letter patterns others do not.
Do you ship boat lettering to my state?
All 50 states and DC, free. We cut for every state's registration number format and ship the next business day.