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HIN decoder: read the hull number of a boat

Type in the hull number of your boat. The decoder splits it into its parts and shows the country of manufacture, the manufacturer code, the serial number, the month and year the boat was built and its model year. The number stays in your browser; only the manufacturer code is looked up when you ask for it.

Where to find the number on the hull, how to read it and when you need it is covered in our guide HIN number on a boat.

Enter the number

Examples:

The decoder only checks whether the number follows the required structure. It cannot tell whether the number is genuine or belongs to this boat. For that, compare the number on the hull with the papers and ask the builder if in doubt.

How the hull number is built

Under the EU Recreational Craft Directive every craft placed on the market must carry an identification number that includes the manufacturer's code, the country of manufacture, a unique serial number, the year of production and the model year. The detail is set out in ISO 10087: 14 characters plus a hyphen after the country code, with no spaces or slashes. This is the number often called the CIN.

European format, the builder Buster's own example: FI-BUSA0001K506
Positions 1 and 2	Country of manufacture as an ISO 3166 code, such as GB, FR or IT, followed by a hyphen.
Positions 3 to 5	Manufacturer code, issued by a competent body in the country of manufacture.
Positions 6 to 10	The builder's serial number in letters and digits, excluding I, O and Q.
Position 11	Month of production as a letter, from A for January to L for December.
Position 12	Last digit of the year of production.
Positions 13 and 14	Last two digits of the model year.

Boats built for the US market carry a HIN, the Hull Identification Number, under US Coast Guard rules. It has 12 characters with no hyphen, and the country code US may be placed in front of it. The 12 characters match positions 3 to 14 of the European number.

US format under 33 CFR 181.25
Positions 1 to 3	Manufacturer identification code (MIC) assigned by the US Coast Guard, or the importer's code for imported boats.
Positions 4 to 8	Serial number, excluding I, O and Q.
Position 9	Month of manufacture or certification, A for January to L for December.
Position 10	Last digit of the year of manufacture or certification.
Positions 11 and 12	Last two digits of the model year.

Build year and model year are not always the same. The model year is the twelve month period in which a model is meant to reach the market for the first time; if that period spans two calendar years, the builder chooses which year to use. A boat built in the autumn for the following season therefore often carries next year as its model year.

Where the number sits on the boat

US rules fix the place exactly: on the outside of the transom on the starboard side, within two inches of the top. Boats without a transom carry it at the stern on the starboard side of the hull. A second, identical number must be fixed in a hidden place inside the boat or under a fitting.

For CE marked craft, ISO 10087 sets out where and how the number is applied. Look first on the outside of the transom, starboard side. The number is stamped, moulded in or on a plate fixed so firmly that it cannot be removed without trace.

Signs that a number has been tampered with

US rules require the number to be fixed so that any change or removal is obvious, and a plate must be attached so that taking it off leaves marks on the hull. When buying, look out for these signs:

The area on the transom has been sanded, filled or freshly painted, or the gelcoat there is a different shade.
The plate is held by new rivets, screws or glue, or it moves.
The characters are of uneven depth, crooked or in different typefaces.
A hidden second number inside differs from the one on the transom or has been made unreadable.
The number does not match the bill of sale, invoice, declaration of conformity or registration papers.
The decoder reports a structural error, such as I, O or Q in the serial number or a month letter after L.
The build year or model year in the number does not match the year given in the advert.

If you see any of these signs, do not buy until the boat's history is clear. Check the number against the list of stolen boats and report any suspicion to the police. Also look at the boat recalls for the model.

Guide: HIN number on a boat Used boat checklist Stolen boats Boat recalls

Sources

Manufacturer codes: US Coast Guard list (MIC.csv, file dated 18 Oct 2019), a work of the US Government in the public domain. Only the code and company name are used.