HINs Explained

A boat's Hull Identification Number (HIN) is similar to the Vehicle Identification Number (VIN) found on cars and trucks. As per the U.S. Coast Guard, all boats built in the U.S. since 1972 must have a unique HIN. Like a VIN, a HIN's location for display is standardized, though that location varies more with boats as they tend to be of radically different designs.

Anatomy of a HIN

To paraphrase the formal regulations, some of the current requirements for a valid HIN are as follows:

  • It must contain 12 uninterrupted digits comprised of English alphabet letters and Arabic numerals.
  • The letters I,O, and Q are prohibited from use within the manufacturer's serial number portion of the HIN (digits 4-8).
  • The first three digits must represent a valid Manufacturers' Identification Code (MIC) issued by the United States Coast Guard (USCG).
  • The last four digits must comprise a proper dating code sequence containing the month and year of production as well as the model year of the boat.
  • A two-letter country code may be installed to the left of the HIN and separated by a hyphen. This code (example: "US-") is not technically part of the HIN here in the United States.

What is a HIN?

boat diagram

H=Hull, I=Identification, N=Number
A HIN is the nautical equivalent of the VIN (Vehicle Identification Number) on your car. It is 12 digits in length but may be preceded by two letters and a hyphen, which represents the country of origin code (e.g. "US-"). These two letters and the hyphen are not technically part of the HIN in the U.S., but they are part of European Union country HINs.

Where is the HIN located on a boat?

Generally speaking, looking at the boat from astern (from the back), the HIN should be in the upper right corner of the transom. It should be within the 2 inches below the rub rail and usually within 12 inches of the side of the boat. Locations can vary somewhat but it should always be on the starboard (right) side of the transom.

What is HIN validation?

HIN validation is the process by which a HIN is tested or inspected to see that it complies with the federal rules mandating the length, composition, and format of a "legal" hull identification number.

Does every boat have a HIN?

As per the USCG, all 1973 and newer model boats have HINs. If your boat is older, it probably does not have a HIN.

A VIN describes the car it's on. Does a HIN describe its boat?

Generally speaking, NO. The VIN is longer and contains codes for engine type, model, and color, but a HIN does not. There has been talk of expanding the HIN to 17 digits to accomodate these identifying codes, but this has not yet come to pass. The information a HIN does contains includes the manufacturer, the model year, when it was built, and the production or serial number that the builder assigned to the hull.

What does a HIN look like?

Most often the HIN will appear in one of two ways. It may be molded into the hull using reverse lettered tape, so you will look for a narrow rectangular indentation with letters and numbers in it. It will usually be the same color as the hull, roughly one half inch high, and 3 inches long. The second common HIN application is a metal plate usually held on by two rivets. Regular screws are not allowed. On the plate is stamped or engraved the HIN. A HIN could also appear to have been carved or engraved on the hull.

Is the HIN the boat's serial number?

Like the VIN on a motor vehicle, the HIN is the unique identifier for the whole vessel as defined and named by law. There are many parts which have serial numbers that go into making a car or boat but there is only one VIN or HIN. When we talk about the "manufacturer's serial number portion of the HIN," this is referring to digits 4-8 of the HIN (see "Anatomy of a HIN" above). Those five digits represent the serial number of this particular hull, but they are only one component of the 12-digit HIN.

Does the HIN ever get checked by marine police or the U.S. Coast Guard?

Yes. It is currently part of the USCG's routine or Standard Operating Procedure (SOP) to include the HIN on reports stemming from vessel stops or inspections. Some law enforcement officers check it and some don't, but they may see it if they wish to.

Is the state registration number on the bow a HIN?

Although law enforcement can identify a boat using the State Numbering System (SNS) registration number/stickers found on the bow of a boat, that number is not the HIN. The HIN will be found at the other end of the boat on the transom.

If the third letter of a HIN is a "Z" why should I take special notice?

When the third digit of a HIN is a "Z," this indicates that the HIN has been state-issued or "re-tagged." In these cases, the "Z" will be preceded by the issuing state's abbreviation (e.g. "NYZ" or "FLZ"). There are a few ways this can happen. It could have been a home made boat and its builder requested that a HIN be issued by the state; this is completely legal and correct. Such a HIN may also indicate that the vessel had been sold as "salvage" and part or most of it was refurbished and presented as a "home built" or "custom made" boat. It may not look home made, but this too is legal within certain guidelines. The important thing is that you are advised of this before you buy the vessel so you can ask any questions you may have about its history and how it came to be re-tagged.