A HIN is a boat's serial number, set by US federal rule in 33 CFR 181.25. It has 12 characters. The first three are the manufacturer identification code, the next five the builder's serial number, then a letter for the month and a digit for the year of build or certification, and the last two are the model year.
On a US boat it's on the starboard outboard side of the transom, near the top, with a second, identical number hidden inside the boat. European boats carry a watercraft identification number (WIN) under the Recreational Craft Directive, with the country code in front.
What a surveyor checks
That the HIN is there and legible, on the transom and in its hidden spot if it can be found. That it matches the title, registration and bill of sale, and the model year the seller claims. A HIN that's been ground off or doesn't match is a finding, because it raises the question of whose boat it is. Decode it with our HIN decoder.
In the report
Record the HIN in the vessel particulars, exactly as read, and where it was read. "HIN read on the starboard transom, matches the registration certificate and the model year stated."