Boat Hull ID (HIN) Lookup: Where It Is, How to Decode It, What It Means for Value
Every boat built or imported since 1972 carries a 12-character Hull Identification Number. It tells you who built the hull, when, and — matched against the title and engine — whether the boat is what the seller says it is.
By Joey Bouza, Founder, US Marine Connection · Updated August 29, 2026
The Hull Identification Number is the boat's equivalent of a car's VIN: a 12-character code the manufacturer molds or engraves into the hull under Coast Guard rules. It is the first thing a surveyor, an insurer, a lender and a buyer will ask for, and it is the fastest way to confirm a boat's model year — which is the single biggest input to any honest valuation. This guide shows where to find it, how to read it, and what to do when it doesn't match the paperwork.
Where to find the HIN
- Primary location: the outside of the transom (the flat back of the hull), on the upper starboard (right, facing forward) corner, within about two inches of the top edge. On most fiberglass boats it is molded into the gelcoat or on a riveted plate.
- On boats with a swim platform, outboard bracket or transom extension that covers that corner, look on the starboard side of the hull just forward of the obstruction, or on the bracket itself.
- Every boat also has a second, hidden HIN somewhere inside — under a hatch, beneath a seat base, inside a locker. Manufacturers do not publish the location; surveyors look for it to confirm the visible number hasn't been altered.
- Pontoons carry the HIN on the starboard rear corner of the deck frame or on a plate on the transom crossmember, not on the tubes.
- Personal watercraft (Sea-Doo, WaveRunner, Jet Ski) put it on the rear of the hull, usually starboard, near the boarding step or beneath the rear grab handle.
Don't confuse the HIN with the engine serial number (on the outboard bracket or a plate on the block), the trailer VIN (on the tongue), or the manufacturer's capacity plate. The HIN is the 12-character code that starts with three letters and ends with the model year.
How to decode a HIN
Since August 1984 the format has been fixed: three letters, five characters, then four characters for the dates. Read it left to right.
| Characters | What they are | Example: SERT1234J506 |
|---|---|---|
| 1–3 | Manufacturer Identification Code (MIC), assigned by the Coast Guard | SER = Sea Ray Boats |
| 4–8 | Hull serial number — the builder's own sequence; letters and digits | T1234 |
| 9 | Month of certification (the month the hull was built), A = January through L = December | J = October |
| 10 | Last digit of the year of certification | 5 = 2005 (read with characters 11–12) |
| 11–12 | Model year | 06 = model year 2006 |
Two things trip people up. First, a boat certified in October 2005 can be a model year 2006 — builders start the next model year in late summer, just as car makers do, so characters 10 and 11–12 will disagree by one and that is normal. Second, boats built between November 1972 and July 1984 used two older formats: one ending in the month and year as letters and digits (for example "M83C" for March 1983), the other ending in a model-year code. If the last four characters don't look like a month letter plus three digits, you are probably looking at a pre-1984 hull.
Looking up the manufacturer code
The Coast Guard publishes a searchable Manufacturer Identification Code database (uscgboating.org). Type the first three characters and you get the builder, its address and whether it is still in business. This matters for value: a hull from a builder that no longer exists can be a fine boat, but parts and factory records are harder to come by, and buyers price that in.
Check it against the paperwork
- Title or registration: the HIN on the state title must match the transom character for character. A one-character difference is usually a clerical error that can be corrected at the DMV or state boating agency before sale — but it must be corrected, because a lender or insurer will refuse a mismatch.
- The hidden HIN: if you can find it, it should match the transom exactly. A transom HIN that has been ground off, re-stamped or covered with a new plate is a red flag for a stolen or rebuilt hull.
- Engine serial: outboards and sterndrives carry their own serial number and model year. An engine several years newer than the hull is a repower — good news if it was done well, and something to confirm with receipts.
- Trailer VIN: a separate title in most states. Confirm it is included in the sale and titled to the seller.
What the year means for value
Once the HIN gives you a model year, you can place the boat against what the market is asking right now. Below is the live median asking price of boats on this site by decade of manufacture; the pattern — a steep drop in the first decade, a long flat tail after — is why the year is the first field on every appraisal form.
| Decade built | Median asking | Listings |
|---|---|---|
| 1990s | $8,247 | 14 |
| 2000s | $12,998 | 46 |
| 2010s | $39,000 | 105 |
| 2020s | $72,495 | 197 |
Year is the starting point, not the answer. Engine hours, whether the boat lived in fresh or salt water, and whether it was stored under cover matter as much as the decade, which is why our value guide asks for all of them.
Frequently asked questions
- Is the HIN the same as the boat's serial number?
- The hull serial number is characters 4–8 of the HIN. The full 12-character HIN is what titles, registrations and insurers use; when someone asks for the serial, give them the whole HIN.
- My boat was built before 1972 and has no HIN. Can I still sell it?
- Yes. Boats built before November 1972 were not required to carry one. Most states will assign a state-issued HIN when you title or register the boat; do that before listing so buyers can get insurance and financing.
- The HIN on the title doesn't match the transom. What now?
- Compare the two carefully — O versus 0 and I versus 1 are the usual culprits. If it is a genuine error, your state boating agency can correct the title with an inspection. Do not sell until it is fixed; the buyer cannot register the boat otherwise.
- Can I look up a boat's history from the HIN?
- Partly. The Coast Guard MIC database gives the builder; state agencies can confirm current registration and liens; paid boat-history services check theft, salvage and lien records against the HIN. There is no single free national record the way there is for cars.
- Where is the HIN on a Sea-Doo or WaveRunner?
- On the rear of the hull, usually the starboard side near the boarding step or under the rear grab handle. Some models also carry it on the footwell or under the seat.
- Does the month letter matter?
- Only to tell a late-year build from an early one. A boat certified in August through December is usually the next model year, which is the number that sets the value.
- What is a state-assigned HIN?
- A 12-character number a state issues for homebuilt boats, pre-1972 boats or hulls whose original HIN is unreadable. It begins with the state's two-letter code followed by Z. It is legal and titleable, but buyers will ask why the boat has one.
- Will a re-stamped or replaced HIN plate lower the value?
- It will lower the number of buyers willing to touch the boat, which comes to the same thing. Get a surveyor to document why it was replaced and keep the paperwork with the title.
About the author
Joey Bouza — Founder, US Marine Connection
Working musician and founder of Prospects International, a marketing firm that runs lead and appointment campaigns for dealers — including boat dealers — across the country.
Prices and counts in our guides come from live listings on this site and are recalculated hourly. Where we quote industry-typical figures (transport quotes, survey fees, winterizing, repower quotes) we say so, and we never publish a number we haven't measured or sourced.