At a glance
- Length
- 12 characters, with no dashes or spaces
- Characters 1 to 3
- Manufacturer identification code (MIC) from the Coast Guard
- Characters 9 and 10
- Month and last digit of the year the boat was certified or built
- Characters 11 and 12
- Model year
On this page
How to read a boat HIN
Coast Guard rules set the layout of every hull identification number on a boat built or imported for sale (33 CFR 181.25). Here it is on a 2025 boat from a Coast Guard recall:
| Characters | What they mean | On BLBX1001F425 |
|---|---|---|
| 1 to 3 | Manufacturer identification code, assigned by the Coast Guard to a builder or importer | BLB: Brunswick Family Boat Co. Inc., Knoxville, Tennessee |
| 4 to 8 | Serial number, in letters, numbers or both, but never I, O or Q | X1001 |
| 9 | Month of certification or manufacture: A for January through L for December | F: June |
| 10 | Last digit of that year | 4: 2024 |
| 11 and 12 | Model year | 25: 2025 |
From Coast Guard recall 26MF0172, which covers 81 model year 2025 D20 boats. A HIN has no check digit, unlike a VIN.
Example: built in 2024, sold as a 2025
The HIN above says the boat was certified or built in June 2024 and carries model year 2025. The rules allow that: characters 9 and 10 give the month and year of certification when one is required, or the date of manufacture otherwise, and that date can't be earlier than the start of construction or later than the day the boat leaves the plant (33 CFR 181.25(c)). Three HINs from Coast Guard recalls:
| HIN | Builder in the Coast Guard's MIC list | Built or certified | Model year | Recall |
|---|---|---|---|---|
| RGR40777D424 | Ranger Boats, Flippin, Arkansas | April 2024 | 2024 | 25CG0018, Ranger VS1665SC |
| BLBX1001F425 | Brunswick Family Boat Co. Inc., Knoxville, Tennessee | June 2024 | 2025 | 26MF0172, D20 |
| DXV14529C525 | Four Sons, Fair Bluff, North Carolina | March 2025 | 2025 | 26CG0010, Coastal Skiff 145 |
Names can differ between records: the Coast Guard's MIC list gives Four Sons for DXV, while recall 26CG0010 names Wilkes Marine.
How to look up a boat manufacturer code
Every builder or importer that puts HINs on boats for sale must ask the Coast Guard for a manufacturer identification code, and a code can't be sold, transferred or borrowed (33 CFR 181.31 and 181.33). When you enter a HIN above, the tool looks up its first three characters in the Coast Guard's MIC list. You can also search that list yourself in the Coast Guard's MIC database.
Expect a lot of history. The Coast Guard's download holds 16,188 codes, and 11,666 of them carry an out-of-business date. Four Winns' old code 4WN, for example, shows Cadillac, Michigan, and an out-of-business date of May 1994. A MIC also follows different rules from the rest of the number: the ban on I, O and Q covers only the serial, so 4,764 codes contain one of those letters, such as AAI for Liberator Boats in Crowley, Texas.
Is a HIN the same as a VIN?
No. A VIN is a 17-character number under NHTSA's rules (49 CFR Part 565), with a check digit in position 9. A HIN is 12 characters under the Coast Guard's rules (33 CFR Part 181) and has no check digit, so NHTSA's VIN database can't read one. That's why this page treats a 12-character entry as a HIN.
The trailer that carries the boat is a road vehicle with its own 17-character VIN; see the trailer VIN decoder. For cars, trucks and motorhomes, use the main VIN decoder or the RV VIN decoder. Selling the boat? Put the HIN on a free boat bill of sale.
Where is the HIN on a boat?
Every boat carries two identical HINs (33 CFR 181.29):
- Primary: on the starboard (right) outer side of the transom, within 2 inches of the top of the transom, gunwale or hull-to-deck joint, whichever is lowest. Boats without a usable transom carry it on the starboard side of the hull, within 1 foot of the stern. Catamarans and pontoon boats with replaceable hulls carry it on the aft crossbeam, within 1 foot of the starboard hull.
- Duplicate: somewhere hidden inside the boat, or under a fitting or piece of hardware.
The characters must be at least a quarter inch high and fixed so that any change would be obvious. "US-" in front of a HIN is a country code, not part of the number (33 CFR 181.27).
Older, homemade and imported boats
The Coast Guard's HIN rules date from a 1983 rule (48 FR 40718), so an older boat's number may not follow the layout above. Someone who builds or imports a boat for their own use, not for sale, gets a HIN from the issuing authority in the state where the boat is mainly used (33 CFR 181.23(b)). An importer of foreign-built boats gets its own MIC, or may use another country's numbering system if the Coast Guard has accepted it (33 CFR 181.31(b)). Nobody may remove or alter a HIN without the Coast Guard's permission (33 CFR 181.35), so a missing or reworked number is a reason to stop and ask questions.