All boats manufactured or imported on or after November 1, 1972 must bear a HIN (Hull Identification Number), a 12-character alpha-numeric ID that uniquely identifies your boat.

A HIN is not the same as a State registration number, which is usually displayed on the bow of your boat. The boat’s registration number is a State requirement similar to the license plate on your car. The HIN, however, is required to be shown on the State certificate of registration just as the VIN is required for a vehicle.

The boat manufacturer must display a hull identification number, no less than one-fourth of an inch high, on each boat hull. The primary HIN must be permanently attached to or engraved into the outer right (starboard) side of the transom within two inches of the top. On boats without transoms or on boats on which it would be impractical to affix a number to the transom, the HIN must be affixed to the starboard outer side of the hull, aft within one foot of the stern and within two inches of the gunwale. Catamarans and pontoon boats may have the HIN on the rear crossbeam within one foot of the starboard hull attachment.

Boats manufactured or imported on or after August 1, 1984, also have a duplicate secondary HIN somewhere on an unexposed location inside the boat or beneath a fitting or item of hardware. It is illegal for anyone (manufacturer, dealer, distributor, or owner) to alter or remove a HIN without the express written authorization of the Commandant, U.S. Coast Guard.

The first eight digits of a HIN have the same meaning for all boats.

THE FIRST THREE CHARACTERS are the Manufacturer Identification Code (MIC) assigned by the Coast Guard to the manufacturer or the person importing the boat. You can check the USCG website for meanings:

The Manufacturer's Identification Code may be similar or identical to the company name, such as "AMF" or it can be confusing. My Mistral 12 dinghy, for example, was manufactured by Canadian Yacht Builders of Quebec, indicated by the letters ZMI_ _ _ _ _ _ _ _ _ (see photo). Spacing of characters means nothing!

CHARACTERS FOUR THROUGH EIGHT are the serial number assigned by the manufacturer (_ _ _00394_ _ _ _). These are normally numbers, but letters (except I, O, or Q) may also be used in the serial at the discretion of the manufacturer.


The last four digits can be confusing thanks to government agents who invented the system. Here is an attempt to clarify the different types.

EARLY HIN TYPES, November 1, 1972 through July 30, 1984

The manufacturer had the option of giving either the model year or date of manufacture. As with cars, a model year can be several months different from the date of manufacture.

A. Straight date HIN: Example: ABC123451272 (December, 1972)
The 9th and 10th characters give the month and the 11th and 12th characters denote the year of manufacture.

B. Model Year HIN: Example: ABC12345M67J (May, 1967)
The 9th digit is an "M", which stands for model year.
The 10th and 11th characters are numeric and denote the model year.
The 12th and final digit gives the month of manufacture using letters of the alphabet.

Because some months have the same beginning letters (March and May, January, June and July) it is understandable that one can't use the first letter of each month, so inventors of the system decided to use letters of the alphabet consecutively (A through L). Here comes the stupid part! "A" stands for August, but not because the month's name begins with an "A". The government officials simply decided to start lettering months with August and end with July! In order to figure out your HIN you may need to check the following chart:

A=August, B=September, C=October, D=November, E=December,

F=January, G=February, H=March, I=April, J=May, K=June, L=July

NEW HIN, August 1, 1984 through present

If the 9th character in a HIN is an "M" or a number, it is a pre-August 1984 boat.

The 9th character now designates the month of manufacture in alphabetical form, but the sequence is now logical A= January and L= December .

The 10th character is now the confusing one. It designates the year of manufacture, but gives only the last digit. This must be interpreted by the final two characters, which designate the model year. If the last four digits are J900, the boat is a 2000 model built in October, 1999. If the last four digits are G000, the boat is a 2000 model built in July, 2000.

Individuals building boats for their own use and not to sell must obtain a 12 character HIN from their State. The Manufacturer Identification Code at the beginning of the HIN for a "home built" boat is an abbreviation for the State followed by a "Z" which indicates that it is a State identification.

Some manufacturers add additional information after the HIN, such as -21 to indicate that the craft is a 21-foot model.

The government will have to change the system again before 2084 to avoid confusion, but a 17-character internationally recognized HIN is likely coming soon.