State Compliance Guide

California Boat Registration Decal Requirements

Every motorized vessel operated on California public waters must display its CA-prefixed registration number on both sides of the forward half of the hull, along with the current state validation decal. California enforces specific rules on letter height, font style, color contrast, separator spacing, and exactly where the validation decal sits relative to the number. The summary below covers the requirements most commonly missed during inspections.

Quick reference

Letter height
3″ minimum
Font
Plain, vertical block font
Contrast
Required — must contrast with hull
Separator
Space or hyphen
Decal placement
Exactly 3 inches behind (aft of) the registration number sequence

Detailed rules

Letter height and font

Letters and numbers must be at least 3 inches tall, in plain, vertical block font. Script, italic, shadowed, and outlined fonts are not acceptable. Stroke width should be heavy enough that the sequence reads cleanly from at least 100 feet away in daylight.

Color and contrast

The number must be a color that sharply contrasts with the hull. Light hulls (white, cream, light gray) require dark letters; dark hulls require light letters. Reflective vinyl is permitted as long as the underlying contrast holds during the day.

Separator between prefix and digits

Space or hyphen must separate the CA prefix, the digit group, and the suffix letters. Example: CA 1234 AB or CA-1234-AB. Running the characters together is a violation.

Validation decal placement

Exactly 3 inches behind (aft of) the registration number sequence. The decal must be on both sides of the forward half of the hull and clearly visible from the side of the vessel.

Position on the hull

Numbers go on both sides of the forward half of the vessel, above the waterline, in an unobstructed location, reading left to right. Anything that covers or partially obscures the sequence — rub rails, fenders, accessories — can cause an inspection failure.

Common compliance mistakes

  • Using script, italic, or outlined fonts that look great on a boat name but fail California inspection.
  • Placing the validation decal in the wrong position relative to the number — see the rule above for exact California placement.
  • Letters under 3" tall because they had to fit a narrow accent stripe.
  • Low-contrast color combos like dark navy numbers on a black hull stripe.

Frequently asked questions

How tall do California boat registration numbers have to be?

At least 3 inches tall, measured from the top to the bottom of the character, in plain, vertical block font.

Can I use a stylized or script font on my California boat?

No. California requires plain, vertical block characters. Script, italic, shadowed, and outlined fonts are not compliant.

Where does the validation decal go on a California-registered boat?

Exactly 3 inches behind (aft of) the registration number sequence, on both sides of the forward half of the hull.

Do I need a hyphen between CA and the numbers?

Space or hyphen. CA 1234 AB and CA-1234-AB are both acceptable; CA1234AB is not.

Decals must be securely affixed on the forward half of each side of the hull — anything I should know?

Decals must be securely affixed on the forward half of each side of the hull.

Ready to design your CA decals?

Our online designer enforces the 3-inch height, plain block font, and contrast rules automatically — so what you preview is what passes inspection.

Source: Reference · Always verify current requirements with your state boating authority before relying on this guide for compliance.