📋 Boat Registration Numbers & CF Numbers — Size, Placement & State Rules

Every motorized vessel and most sailboats operating on US waters must display a state-issued registration number on the hull. The rules look simple but the details matter — wrong size, wrong placement, or wrong font can earn you a citation. This guide covers the federal baseline, what individual states change, how to buy compliant decals, and every common mistake to avoid.

Quick Answers

What is a CF number?

A CF number is a California boat registration number. When you register a boat with the California DMV, it’s given a permanent number that starts with CF — California’s state code in the federal boat numbering system (California uses CF, not CA) — followed by up to four numbers and up to two letters:

• Display it on both sides of the bow (front half of the boat), in plain block letters at least 3 inches tall, contrasting with the hull, with a space or hyphen between each part: CF 1234 AB or CF-1234-AB.
• Sticker: put the current California registration sticker on each side, in line with the number and about 3 inches toward the stern (behind it).
• Who needs one: any undocumented motorboat in California, and sailboats over 8 feet long.

What is a CF number for the DMV, and where do I find mine?

The CF number is how the California DMV identifies your boat. You’ll find it on your vessel registration card, on your DMV renewal notices, and on the bow of the boat. You need it to renew your registration, transfer ownership, replace a lost sticker or registration card, and report a stolen boat. The CF number is permanent and stays with the boat when it’s sold, so a used boat should already have one — ask the seller for the registration card. Bought a boat that was never registered in California, or brought one from another state? Register it with the DMV and you’ll be issued a CF number. Federally documented boats don’t get a CF number.

What does a boat registration number mean?

Every US state registration number has three parts: two letters for the issuing state (FL Florida, CF California, WN Washington, HA Hawaii, NY New York, TX Texas…), then up to four numbers, then up to two letters — or up to three numbers followed by up to three letters, like WN 567 EFG. The letters I, O and Q aren’t used in the suffix because they look like 1 and 0. The number is how police, the Coast Guard, search-and-rescue crews and your state agency identify the boat. It is not the same as the HIN (hull identification number), the 12-character serial number molded into the transom by the builder. See number format below.

Do yachts need registration numbers?

It depends on whether the yacht is state-registered or federally documented:

• State-registered yacht: yes — it displays its state registration number and sticker on the bow like any other boat, whatever its size.
• USCG-documented yacht: no state numbers on the hull. Federal rules (33 CFR 173.11) exempt documented vessels from state numbering. Instead it shows its name and hailing port on the hull in letters at least 4 inches high, and its official number is marked inside the hull. Boats of at least 5 net tons can be documented — typically about 25–26 feet and up for a sailboat.
• Check your state: some states still require documented boats to register with the state or display a state decal, even though they don’t display state numbers. See documented vessels below.

Do sailboats need to be registered?

Any sailboat with a motor (outboard or inboard) must be registered in every state unless it’s federally documented. For sailboats without a motor, it varies by state: California, for example, requires registration for sailboats over 8 feet, while some states exempt small non-motorized sailboats. Check your state boating agency’s rules.

How do I avoid common boat registration mistakes?

The mistakes that most often get boaters cited: numbers under 3 inches, script or italic fonts, numbers on the back half of the hull or on removable canvas, groups run together (FL1234AB), numbers that blend into the hull color, an expired or missing sticker, and leaving the registration card at home. The full list and typical fines are in common mistakes to avoid below.

Federal Baseline Rules (33 CFR 173)

The following requirements apply in every US state. States can add stricter rules, but none can require less than this.

Registration Number Format

All US state registration numbers follow the same three-part structure:

• State prefix: Two letters identifying the state of registration. Most match the postal abbreviation (FL = Florida, NY = New York, TX = Texas), but not all: California is CF (not CA), Washington is WN, and Hawaii is HA.
• Numeral group: Up to 4 digits assigned by the state DMV or boating agency.
• Letter suffix: Up to 2 letters. Federal rules (33 CFR 174.23) also allow up to 3 digits followed by up to 3 letters (e.g. WN 567 EFG). The letters I, O and Q are never used in the suffix.
• Separators: Each group must be separated by a hyphen or space of letter-width. Both FL-1234-AB and FL 1234 AB are valid. FL1234AB with no separation is not.

Letter Size & Font Requirements

Minimum Height: 3 Inches

Three inches is the federal floor for state-registered boats. This means the actual printed character height — not the font size in your design software — must measure at least 3 inches from top of letter to bottom.

Allowed Font Styles

Placement Rules

Where the Numbers Go

• Must appear on both sides of the hull (port and starboard).
• Must be in the forward half of the vessel — the bow 50% of hull length.
• Must be above the waterline and below the deck/gunwale, clearly visible.
• On most sailboats and powerboats, numbers go on the bow area — the typical location is on each bow, forward of any cabin or deck hardware.
• Must not be placed on a removable item (not on a bimini, not on a canvas cover).

Height Above Waterline

Federal rules do not specify a precise height above the waterline — they only say "between the waterline and the deck." Practically, aim for a position that is:

• Clearly visible when the boat is at normal flotation (not hidden by spray rails, rub rails, or waterline).
• Not so high that it sits above the sheer line or gunwale.
• Consistent on both sides — same height port and starboard looks professional and avoids questions.

Color & Contrast Requirements

The rule is simple: letters must contrast with the background. There is no federally mandated color — any color works as long as it's clearly visible against the hull.

Validation Stickers (Registration Decals)

Your state issues annual or biennial validation stickers (decals) along with your registration card. These prove your registration is current and must be displayed near the registration numbers.

Federal Baseline

• Sticker must be placed within 6 inches of the registration numbers.
• Must be on the same side as the registration number — one sticker per side.
• Must be clearly visible and legible.

Common State Variations

• Maryland: Sticker may be placed within 3 inches of the number in any direction.
• Pennsylvania: Within 6 inches, must be horizontally aligned with the registration number.
• Some states: Specify port side only, others require both sides; always follow the instruction sheet that came with your decals.
• Ohio, Michigan, Minnesota: Sticker goes after (aft of) the registration number on the starboard side.

Common Boat Registration Mistakes to Avoid (Dos & Don'ts)

Common Violations & Penalties

State-by-State Differences

All states follow the federal 33 CFR 173 baseline. The table below highlights where specific states go further or have notable quirks. If your state isn't listed, the federal baseline rules apply without modification.

Documented Vessels (USCG)

Vessels with USCG federal documentation (common on boats over 26 feet and boats used commercially) follow different rules:

• Display the vessel name and hailing port on the hull — not a state registration number.
• Name and hailing port must be in Roman alphabet letters not less than 4 inches in height.
• The USCG documentation number must be marked on an interior structural member in 3-inch Arabic numerals.
• A documented vessel still needs a state use decal or sticker in many states for operating on state waters.

Where to Buy Compliant Registration Decals

Pre-cut, pre-spaced marine vinyl decal sets are the easiest and most reliable way to stay compliant. Avoid hand-cut or generic signage vinyl — marine-grade products resist UV, salt, and fuel splashes far better.

What to Look for When Buying

• Marine-grade or outdoor-rated vinyl — minimum 5-year UV rated. 3M 180/280 series or Avery MPI series are the industry standards.
• Pre-spaced kits — letters and numbers already positioned with correct separator spacing on a transfer tape backing. Much easier than spacing individual characters yourself.
• Two-set kits — you need one set for each side of the hull. Many budget listings on Amazon are single sets — read carefully.
• Block (not serif) style — confirm from the product image that the font is plain block, not a decorative style.
• Minimum 3-inch character height — verify this in the listing, not just the product title.

✅ Pre-Season Registration Number Checklist

• □ Numbers on both sides of the bow
• □ Letters are at least 3 inches tall (measure if unsure)
• □ Plain block font — no italic, no script
• □ Contrasting color against hull — clearly legible at 20 feet
• □ All three groups properly separated by hyphens or spaces
• □ Numbers in the forward half of the hull
• □ Current-year sticker within 6 inches of number
• □ No sticker layering — old sticker fully removed
• □ No peeling, cracking, or fading — replace if in doubt
• □ Registration card on board and current