Every boat built or imported since 1972 carries a 12-character Hull Identification Number. Here's where to find it, what each part means, and how to instantly identify the manufacturer from the first three characters.
Enter the first 3 characters of your HIN (the MIC), or a builder name.
A modern HIN looks like this — 12 characters, no spaces. Here's how it breaks down:
Characters 1–3 — Manufacturer Identification Code (MIC). A unique code the U.S. Coast Guard assigns to each boat builder. This is the most useful part for identifying who built your boat — and it's exactly what HullSource looks up. In the example, BWC is Boston Whaler.
Characters 4–8 — Hull serial number. Assigned by the manufacturer to that individual hull. There's no universal standard for how builders number their hulls, so the serial alone rarely decodes to anything without the builder's own records.
Characters 9–12 — Date of certification / model year. Under the current (post-1984) format, these encode the month and year the boat was built plus its model year. Older HINs used different date formats, so this portion can be ambiguous on pre-1984 boats.
Look on the starboard (right) side of the transom — the flat surface at the very back of the boat — in the upper corner, within two inches of the top. It's stamped, molded, or on a riveted plate. On boats built since 1984, a second, identical HIN is hidden in an unexposed spot elsewhere on the hull (under a fitting, inside a locker) as a theft deterrent. If you can't find it on the transom of an older boat, check the transom plate, the interior, or your registration and title documents.
The MIC reliably identifies the builder, which is why it's the anchor of this site: type your three characters above and you'll get the official Coast Guard record plus, for many builders, company history and where owners find parts. The date portion gives you a build/model year on standard modern HINs. The serial number, on its own, usually can't be decoded to a year or model without the specific builder's production records — and for many defunct builders those records no longer exist. We don't guess at those; where the honest answer is "the builder's records would be needed," we say so.
MIC codes are not permanent. When a builder closes, the Coast Guard can reassign its three-character code to a different company years later. That means a very old hull number might return a builder that has nothing to do with your boat — and it's one reason old-boat identification is genuinely hard. If your lookup returns something that doesn't fit, that mismatch is itself a signal your builder may be long out of business.
Where is the HIN located on a boat?
The primary HIN is stamped or molded into the hull on the starboard (right) side of the transom, in the upper corner within two inches of the top. Since 1984 a duplicate HIN is also placed in an unexposed location elsewhere on the boat. On older boats it may be on a plate.
What do the first three letters of a hull number mean?
The first three characters are the Manufacturer Identification Code (MIC), a unique code the U.S. Coast Guard assigns to each builder. You can enter those three characters in the lookup on this page to find the builder.
Can a hull number tell me the exact year of my boat?
The HIN encodes a model year and a month/date of certification, but the format changed over the years and older or non-standard HINs can be ambiguous. The MIC (builder) portion is the most reliable part to decode.
What if my MIC isn't found?
MIC codes are sometimes reassigned after a builder closes, and some older codes were retired. If your code returns no match or an unexpected builder, that itself is a clue the original builder may be out of business.
Is a HIN the same as a VIN?
No. A HIN (Hull Identification Number) identifies a boat's hull, similar in spirit to a car's VIN but with its own 12-character Coast Guard format and its own rules.
Ready to identify your boat? Browse all builders, jump to builders by state, or use the lookup at the top of this page.