The HIN is on the starboard (right-hand) side of the transom, within two inches of the top of the transom, gunwale or hull-deck joint. That position is set by federal regulation, so it is the same on every boat built for US sale since 1972 — you are looking at the back right corner of the boat, near the top edge.
Stand behind the boat looking at the transom. Starboard is on your left as you face the stern from behind. The number will be either stamped directly into the fibreglass or metal, or on a riveted or bonded plate. On outboard boats it is often partly hidden behind the engine bracket or swim platform, so it is worth getting low and looking under overhangs before deciding it is missing.
On a pontoon boat the transom is not a single flat panel, so builders normally place the plate on the starboard rear crossmember or the top of the starboard log at the stern. Our Bennington pontoon page covers this in more detail.
On boats built for US sale since August 1984, federal rules also require a duplicate HIN in an unexposed location — somewhere not visible without dismantling part of the boat. Builders choose their own spot and do not publish it, which is exactly the point: a thief who grinds off the transom number does not know where the second one is.
Common hiding places include under the deck or sole, inside a locker or bilge, beneath the console, under trim near the helm, or laminated inside the hull-deck joint. If you are buying and the seller cannot help you locate it, the manufacturer's customer service can often tell you where that model hides it.
Marine surveyors report that a common reason a transom HIN cannot be read is not tampering at all. When a boat is repainted, a yard may spray high-build primer straight over the number instead of masking it with tape first. Look for a faint outline of the characters or the edges of a plate under the paint.
Do not sand or scrape it yourself on a boat you do not own yet. On boats built since August 1984, find the hidden duplicate HIN instead and check it against the title and registration. Older boats have no duplicate, so the paperwork and a professional survey carry more weight. Ask the seller to have the transom number uncovered properly before you buy. If neither number can be read, treat that as a reason to stop, not something to take on the seller's word.
| Document | Notes |
|---|---|
| State registration card | Carry it aboard; quickest way to confirm the number |
| Title certificate | Must match the transom exactly |
| Insurance policy | Listed as hull number or serial number |
| Bill of sale | Check it before signing, not after |
| Manufacturer's certificate of origin | New boats only |
Because the HIN is the one thing tying a physical boat to its paperwork, it is the thing a fraudulent seller has reason to alter. Treat any of these as a reason to stop:
A mismatch is not always fraud — clerical errors on old paperwork are real — but it must be resolved before money changes hands, not after.
Type the 12 characters from your transom and get the model year, build date, manufacturer on record and open recall status — free, no account needed.
Run a free HIN checkFound the number? Read it character by character, or check what a HIN actually records. Buying rather than checking your own boat? Boat title vs HIN explains which document proves what.