Many states issue a validation sticker (decal) with the certificate of number. The federal rule sets only a frame for state systems: if a state issues validation stickers, its rules must require them to be displayed within 6 inches of the number, and the stickers are approximately 3 inches square (33 CFR 174.15(a)-(b)).
The rule also fixes a colour rotation for the year a sticker expires: blue, international orange, green and red in turn, starting with blue for 1973 (174.15(c)).
What this means for your layout
- Leave room within 6 inches of the number for the sticker, on the side your state says (often aft of the number).
- Exactly where, and on which side, is the state's rule. Read your state's boating guide before you letter.