The registration number and registration decals must be displayed as follows.
- Number must be painted, applied as a decal, or otherwise affixed to the forward half of each side of the vessel, placed for maximum visibility.
- No other numbers may be displayed on either side of the bow.
- Number must read from left to right on both sides of the vessel.
- Number must be in at least three-inch-high, bold, BLOCK letters.
- Number's color must contrast with its background.
- Letters must be separated from the numbers by a space or hyphen: IA 3717 ZW or IA-3717-ZW.
- Decals must be affixed on each side of the vessel, toward the stern of the registration number, 4 inches from and in line with the number.
For vessels with sails, the requirements may be different from those above.
- If a vessel is propelled by sail alone, the registration number may be placed in a position to provide maximum visibility, including placement on the mast.
- A sailboard is not required to display the registration number, but the decal must be placed on the bottom surface of the bow of the sailboard.