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Deciphering an HIN

Deciphering an HIN

Sponsored by Good Old Boat Magazine

How to read your boat's "birth certificate"
by Don Launer

Unless you have a really old boat, you probably have a set of 12 characters embedded on the upper starboard side of your boat's transom. This is your boat's birth certificate, the Hull Identification Number (HIN). It shows the parent-age and date of birth of your vessel. This identification is similar to the 17-character automobile identification number that's on the lower left side of any auto dashboard close to the windshield -- the Vehicle Identification Number (VIN). All boats that were either manufactured or imported after November 1, 1972, are required by law to have an HIN and -- just as you would have a duplicate of your own birth certificate -- it's a good idea to record your HIN or a rubbing of it in your records.

The HIN on my schooner, Delphinus. THB represents the builder, Ted Hermann Boats. It is hull #31, and uses the pre-1984 straight-year format, with 08 representing August and 80 for 1980.

In addition to manufactured boats, this regulation also applies to backyard boatbuilders. Even though an individual plans to build a boat for his own use, he must obtain the 12-character HIN number from his state's boating agency. In the case of a home-built boat, the first three characters in the HIN, which are the Manufacturer's Identification Code, are composed of the 2-character state identification followed by "Z" -- indicating a home-built boat. Thus, for a home-built boat in Minnesota, the first three characters in the HIN would be "MNZ."

The 12-character HIN bears no relationship to your state boat registration number, the number you apply to the port and starboard sides of your bow (unless your boat is documented). Instead, the HIN is federally mandated. In spite of the fact that it is a federal number, it must be shown on the state boat-registration certificate.

To read your boat's birth certificate, you have to be able to decipher the format of those 12 characters on the stern. There have been several formats for the HIN over the years, and it's probable that new formats will emerge in the future. From its inception on November 1, 1972, the HIN was designated by one of two formats.

HIN formats

The manufacturer had a choice of using either the model-year format or the straight-year format, both of which identified the month and year of production.

• Characters 1, 2, and 3 of the HIN are the Manufacturer's Identification Code, and are assigned by the federal government.

• Characters 4 through 8 are the alpha-numeric serial number, which is assigned at the discretion of the manufacturer (I, O, or Q cannot be used in this serial number).

• In the model-year format, the 9th character will always be M, indicating the manufacturer is using the model year format. Then characters 10 and 11 indicate the year, and character 12 is a letter indicating a month, starting with August. Thus, if characters 9 through 12 of the HIN were "M80B," the boat was built in September of 1980. Why the lettering of the months in the model year system began with August is incomprehensible.

• In the numerical straight-year format, characters 9 through 12 are simply the month and year of production. Thus, 0879 would indicate August 1979.

This Hunter sailboat shows the manufacturer's code, HUN, and since the hull is pre-1984, the model-year format was selected. Many manufacturers add additional, optional information to the goverment'mandated HIN. In this case, the -27 included after the 12-character HIN shows
that this boat is their 27-foot model.

New format

Optional, as of January 1, 1984, was a new-format version, simply called new format. This format became mandatory August 1, 1984, replacing the two previous formats.

• In the new format, characters 1, 2, and 3 of the HIN are still the Manufacturer's Identification Code. Sometimes the letters of this manufacturer's code easily identify the manufacturer. In other cases they bear no relationship to the manufacturer's name.

• Characters 4 through 8 are still the alpha-numeric serial number assigned at the discretion of the manufacturer. Some of these manufacturer-assigned characters are laid out very logically, and some defy logic. On a 37-footer, which is hull #51, the number might be 37051; but it also might be a set of characters that only makes sense to the builder.

• Character 9 indicates the month of manufacture or certification. A designates January, B February, and so on through December (a big improvement over the original lettering system that started in August).

• Character 10 is a numeral that indicates the last digit of the year of manufacture or certification.

• Characters 11 and 12 indicate the model year. Thus, 82 would indicate the boat's model year was 1982.

• Some manufacturers also add additional information after the HIN, such as -27, which might indicate that this is their 27-foot model.

After August 1, l984, boat manufacturers were required to display two identical Hull Identification Numbers, one on the outside starboard side of the transom, within two inches of the top of the transom, gunwale, or hull-to-deck joint, whichever is lowest. On boats where this is impossible, such as double-enders, the HIN must be on the starboard side of the hull, within one foot of the stern and within two inches from the top of the hull, gunwale, or deck joint.

The second HIN must be inside the hull in an unexposed location or beneath a fitting or item of hardware.

The HIN characters, both inside and outside the hull, must be no smaller than -inch high, but many manufacturers make them much larger. It is illegal for anyone to alter or remove one of these numbers without written permission of the Commandant of the Coast Guard.


Although the HIN provides a great birth certificate for your boat, there are a few hitches in the system:

• One problem is that foreign manufacturers might use a Manufacturer's Code that is not listed in the United States or might use the same letters as an unrelated U.S. manufacturer. Some United States builders have taken it on their own to add "US" to their HIN to establish the country of origin and solve this problem.

• The present 12-character HIN is becoming obsolete and outdated in today's global marketplace. For years the National Association of State Boating Law Administrators has been recommending that the HIN be increased to 17 characters -- the same number of characters as your automobile's VIN. This expanded HIN would allow additional important information, such as the country of origin, type of vessel, hull material, length of vessel, propulsion, and fuel type.

For now, the 12-character HIN system will serve you as you trace the lineage of the boat you own or the boat you plan to buy . . . until the next format change comes along, of course.

Author's bio

Don Launer is a Good Old Boat contributing editor. He has held a USCG captain's license for more than 20 years. He built his two-masted schooner, Delphinus , from a bare hull and sails it on the East Coast from his home on Barnegat Bay in New Jersey.

Sponsored by Good Old Boat Magazine

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