What Is a HIN? Hull Identification Number Explained
5 min read · Updated May 2026
A Hull Identification Number (HIN) is a 12-character alphanumeric code assigned to every recreational boat manufactured or imported in the United States after November 1, 1972. Think of it as a VIN for boats — a permanent, federally required identifier that follows a vessel throughout its entire life.
The USCG first required HINs under 33 CFR Part 181, which mandated that every boat builder permanently affix a unique identifier to each hull. Before HINs existed, tracking ownership, recalls, or accident history for a specific vessel was nearly impossible. Today, the HIN is the primary key used by every state DMV, the Coast Guard, insurance companies, and services like HullTrace to identify and retrieve records for a boat.
“The HIN is the primary identifier used by every state DMV, the USCG, and insurance companies to retrieve records for a vessel.”
Where to find the HIN on a boat
Federal regulations require the HIN to be permanently affixed in two locations:
- Primary location: On the starboard (right) side of the transom (the flat rear panel of the hull), within two inches of the top of the transom. On most boats this means the upper-right corner of the back of the boat.
- Secondary location: In an unexposed interior location — often under a seat cushion, beneath a hatch cover, or inside a storage compartment. This second HIN is required on boats built after 1984 and exists specifically to detect tampering.
The HIN is usually stamped directly into the gelcoat or hull material, or mounted on a metal plate. If you're inspecting a boat and the primary HIN appears freshly painted over, replaced, or missing — that is a serious red flag. A mismatched or altered HIN can indicate the boat is stolen.
How to read a HIN
Every HIN built after 1984 follows a standardized format. Here's how to decode each segment using an example:
Why the HIN matters when buying a used boat
The HIN is the key that unlocks a boat's history. With a valid 12-character HIN, you can retrieve title transfer records, outstanding liens, Coast Guard-reported accidents, salvage events, and open safety recalls. Run a free HIN lookup on HullTrace to see what records exist for any vessel.
Before agreeing to any used boat purchase, always:
- Physically verify the HIN matches the title and registration documents.
- Check that the secondary (hidden) HIN matches the primary.
- Run the HIN through a history service to check for liens, accidents, and stolen status.
A clean title does not guarantee a clean history. Boats can be damaged, salvaged, or rebuilt and still carry a clean title in many states because marine titling laws are far less uniform than auto titling laws.
HullTrace's free HIN decoder breaks down any 12-character HIN into its manufacturer, serial, production month, production year, and model year — instantly, no account needed.
Frequently asked questions
What is a HIN on a boat?
A HIN (Hull Identification Number) is a 12-character alphanumeric code permanently affixed to every recreational boat manufactured or imported in the US after November 1, 1972. It works like a VIN for boats and is used to track ownership, recalls, and accident history.
Where is the HIN located on a boat?
The primary HIN is on the starboard (right) side of the transom, within two inches of the top. Boats built after 1984 also have a secondary hidden HIN inside a storage compartment or under a hatch cover.
How do I decode a HIN?
Characters 1–3 are the Manufacturer ID Code, 4–8 are the serial number, character 9 is the production month (A=January through L=December), character 10 is the last digit of the production year, and characters 11–12 are the two-digit model year. Use HullTrace's free decoder for any HIN.