A boat hull number is an identification number required for all boats imported or manufactured after November 1972. Known as a hull identification number, it is 12 characters long and unique to each boat.
The first three characters of the hull identification number display the manufacturer’s identification code. The U.S. Coast Guard assigns these codes to manufacturers and importers. The next five characters are a manufacturer-assigned serial number, and the last four characters indicate the date of manufacture and the model year.
The boat's owner must permanently attach the hull number to the outside of the boat on the rear starboard side. Boats built or imported after August 1984 must have another copy of the number attached in a hidden location inside the boat or under a piece of hardware.