HIN decoder: read a boat’s hull identification number
Reviewed 5 primary sourcesSee sources
Every boat built or imported for sale in the U.S. since November 1972 carries a hull identification number. Federal rules fix what each of its 12 characters means, so you can read the builder code, the build month and year and the model year yourself.
The HIN layouts
Current layout (required from August 1, 1984)
| Characters | What they are |
|---|---|
| 1–3 | Manufacturer identification code (MIC). Assigned by the Coast Guard to the builder or importer.[1] |
| 4–8 | Hull serial. Chosen by the manufacturer; letters and digits, but never I, O or Q.[1] |
| 9 | Month. A letter for the month of certification or manufacture: A is January through L for December.[1] |
| 10 | Year digit. The last digit of the year of certification or manufacture.[1] |
| 11–12 | Model year. The last two digits of the model year.[1] |
Model-year layout (November 1972 to July 1984)
| Characters | What they are |
|---|---|
| 1–8 | MIC and serial. As in the current layout.[2] |
| 9 | The letter M. Marks this layout.[2] |
| 10–11 | Model year. Two digits.[2] |
| 12 | Month of production. A letter, with A for August through L for July.[2] |
Straight-year layout (November 1972 to July 1984)
| Characters | What they are |
|---|---|
| 1–8 | MIC and serial. As in the current layout.[2] |
| 9–10 | Month of production. Two digits.[2] |
| 11–12 | Year of production. Two digits.[2] |
Assigned HIN (issued by a state or the Coast Guard)
| Characters | What they are |
|---|---|
| 1–3 | Issuer. A state’s two-letter code followed by Z (for example OKZ), HQZ when the Coast Guard issues it, or USZ when the National Vessel Documentation Center does.[2] |
| 4–8 | Serial. Chosen by the issuer, without I, O or Q.[2] |
| 9–12 | Date of issue. Month letter, then the year written as its last digit followed by its last two digits (2020 is written 020). There is no model year.[2] |
Rules worth knowing
- A HIN is exactly 12 characters, with no slashes, hyphens or spaces.[1]
- “US-” is the only country code allowed next to the HIN; any other number within 2 inches must be set apart by a border or a separate label.[1]
- Boats built abroad and imported for sale carry the U.S. importer’s manufacturer code.[2]
- The same HIN may never be given to two boats, and nobody may remove or alter one without Coast Guard authorization.[1]
- Most manufacturer codes are three letters; a few early ones include digits, and a code can be reassigned once its holder has been out of business for more than ten years.[2]
- Mistyping one character, such as 1 for I, 8 for B or 0 for O, turns a valid HIN into one for a boat that doesn’t exist.[2]
- Before registering or renewing a boat, states check that its HIN meets the federal format and has a valid manufacturer code; a boat over ten years old with an invalid HIN gets a state-assigned one.[3]
- The Coast Guard keeps the list of manufacturer codes, and states use it to confirm a code when they check a HIN.[5]
Where to find the HIN
- On boats with a transom, the primary HIN is on the starboard outside of the transom, within 2 inches of the top of the transom, gunwale or hull-deck joint, whichever is lowest.[1]
- Without a usable transom, it is on the starboard side of the hull near the stern, within a foot of the stern and 2 inches of the top of the hull side.[1]
- On catamarans and pontoon boats with replaceable hulls, it is on the aft crossbeam within a foot of the starboard hull attachment.[1]
- A second, identical HIN is hidden inside the boat or under a fitting; it wasn’t required before August 1, 1984.[2]
Worked examples
BMA45678H485: Current layout: built August 1984, model year 1985 (Coast Guard chart).[2]ABC34567H920: Current layout: built August 2019, model year 2020 (Coast Guard example).[2]BAY68240M83E: Model-year layout: model year 1983, produced in December (Coast Guard example).[2]CCMT23C50379: Straight-year layout: produced March 1979 (Coast Guard example).[2]OKZ12345G818: An Oklahoma-assigned HIN issued in July 2018; the boat itself was built in 2012 (Coast Guard example).[2]
What a HIN can’t tell you
- The HIN gives only the last digit of the build year and two digits of the model year. The decoder picks the decade and century nearest the model year, which is our inference rather than part of the rule.[1]
- The hull serial is the builder’s own; a HIN doesn’t encode the model, length, hull material or engine.[1]
- Boats built before November 1, 1972 had no required HIN; builders used their own serial numbers.[2]
- Assigned HINs (state codes ending in Z, HQZ and USZ) record when the number was issued, not when the boat was built.[2]
Official lookups
- Coast Guard Manufacturer Identification Code search: Enter the first three characters of the HIN to see which builder or importer holds that code, and whether it is still in business.[4]
Sources
Facts on this page are restated in our own words from the regulations, Coast Guard guidance and manufacturer documents below. Check the document for your exact model and year.
- 33 CFR Part 181, Subpart C: Identification of BoatsOffice of the Federal Register / GPO (eCFR) · 33 CFR 181.21-181.35 · §§ 181.23–181.35 (read through the eCFR API, current as of October 1, 2026) · retrieved
- HIN Validation & Verification Guideline (2020)U.S. Coast Guard Boating Safety Division (CG-BSX-2) with NASBLA · Enclosure (1) to CG-BSX-2 Policy #2020-1 · Slides 7–13 (HIN layouts), 25–28 (assigned HINs), 33 (good and bad examples) · retrieved
- Policy 2020-1: Verification of Hull Identification NumbersU.S. Coast Guard CG-BSX-2 · 16751 / Policy #2020-1 (24 Sep 2020) · Paragraph 3.a-3.d · retrieved
- Manufacturers Identification - Search Manufacturers ListU.S. Coast Guard Boating Safety Division · Search form and result pages · retrieved
- Manufacturers of Boats and Associated EquipmentU.S. Coast Guard Boating Safety Division · 'Manufacturer's Identification Code' and 'Apply for a Manufacturer's Identification Code' blocks · retrieved
Primary publishers: Office of the Federal Register / GPO (eCFR), U.S. Coast Guard Boating Safety Division (CG-BSX-2) with NASBLA, U.S. Coast Guard CG-BSX-2, U.S. Coast Guard Boating Safety Division. Spotted an error? Email the address in the footer with the model and the document you are using.