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Decode any boat's HIN. Check for recalls. Free.

Paste a Hull Identification Number and we'll show the registered builder, the model year encoded into the hull, and any open USCG recalls that touch that builder. 16,188 manufacturers and 1,639 recalls indexed. No signup.

12 characters · letters and digits only · find it on the upper-right transom corner

How to read a Hull Identification Number

Every HIN issued since August 1, 1984 follows one fixed 12-character format. Take ABC​12345​D485 as a worked example:

CharactersExampleMeaning
1–3ABCManufacturer Identifier Code (MIC) — assigned by the USCG, decodable above
4–812345Builder's hull serial number (letters and digits, builder's own scheme)
9DMonth of certification: A = January through L = December, so D = April
104Last digit of the certification year — here 1984
11–1285Model year — here 1985

So ABC12345D485 reads: hull 12345 built by manufacturer ABC, certified April 1984, sold as a 1985 model. The certification-year digit repeats every decade by design — the model year resolves which decade you're in.

Older formats (1972 – July 1984)

Boats from the first HIN era used one of two formats, both 12 characters with the same MIC + serial structure but different endings:

  • Straight-year format: the last 4 digits are the month and year of production, e.g. …0378 = March 1978.
  • Model-year format: character 9 is the letter M, characters 10–11 are the model year, and character 12 is a month letter where A = August (model years started in August), e.g. …M78A = model year 1978, designated in August.

Boats built before November 1972 predate the HIN requirement entirely — many have no HIN at all, which is normal for the era, not a red flag in itself.

HIN fraud: what a buyer should check

The HIN is the boat's identity, and altering it is the marine equivalent of VIN tampering. Builders stamp the primary HIN on the upper-starboard transom corner and hide a duplicate somewhere inboard — inside a hatch, under a gunwale, or laminated into the hull. Before money moves on a used boat:

  • Confirm the transom HIN matches the registration and title paperwork character-for-character.
  • Find the secondary HIN and confirm it matches the transom. A mismatch ends the deal.
  • Inspect the transom plate area for fresh gelcoat, paint, or rivet work — scrubbed HINs are usually hidden sloppily.
  • Decode the HIN above and confirm the builder and model year match the listing. A "2005" boat whose HIN decodes to 1998 is a misrepresented listing, whatever the explanation.

HIN vs. registration number vs. documentation number

Three different numbers identify a US boat, and listings confuse them constantly. The HIN is permanent and assigned by the builder — it never changes. The state registration number (e.g. TX 1234 AB, displayed on the bow) is issued by the state, changes when the boat moves states, and identifies the registration, not the hull. A USCG documentation number replaces state registration for federally documented vessels (mostly 5+ net tons used in commerce or kept offshore). For a used-boat purchase the HIN is the number that matters: it's what recalls, manufacturer records, and our Deal Reports key on.

HIN decoder FAQ

What is a HIN?
A Hull Identification Number is the 12-character serial number every US boat builder has stamped onto the upper-starboard transom corner since August 1984. The first 3 characters are the MIC (Manufacturer Identifier Code) assigned by the USCG; the next 5 are the builder's serial; the last 4 encode the certification date and the model year.
Where do I find the HIN on a used boat?
Outside, upper-starboard corner of the transom — the back of the boat, right side as you look forward. Builders are required to display it permanently there. A secondary HIN is also molded into a less visible spot (often inside a hatch or under a gunwale), which is what we use to catch swapped or scrubbed transom plates.
Why didn't my HIN return a manufacturer?
Three common reasons: (1) the hull is pre-1984 and uses an older HIN format; (2) it's a foreign-built boat (only US builders register MICs with the USCG); or (3) the HIN was mis-keyed (zero vs. letter O, one vs. letter I). Re-check the transom plate carefully.
Are these recalls current?
Yes. We ingest the full USCG recall dataset (~1,640 campaigns going back to the early 1980s). Recalls are matched both by MIC (from your HIN) and by builder name, so we surface both hull-specific and brand-wide campaigns.
Can I look up a boat's owner by HIN?
No — and be wary of sites that claim otherwise. Owner information lives in state registration databases and USCG documentation records, which are not public lookup services. A HIN decode tells you the builder, plant, serial, and model year; ownership history requires asking the seller for registration paperwork and matching it against the transom plate.
How do I check if a boat is stolen?
Run the HIN through the NICB's free VINCheck service (it accepts hull identification numbers, not just car VINs) and ask local marine police to run it against state records. Red flags before you even get that far: a transom plate that looks re-riveted or freshly painted around the edges, a primary HIN that doesn't match the hidden secondary HIN, or a seller who can't produce matching registration.
Is a HIN lookup the same as a boat history report?
No. A HIN decode (this page) reads what's physically encoded in the number — builder and model year — and cross-references recalls. Paid 'boat history reports' add auction photos and some title-brand data, but US boat history coverage is far thinner than Carfax-style car data, with no central title database in most states. For a specific boat you're about to buy, a survey plus our Deal Report covers what a history report can't: actual condition, fair value, and known model defects.
Is this really free?
Yes — the decoder and recall checker are free, no signup. We charge $49 for a full BoatVerdict Deal Report on a specific used-boat listing: fair value vs comparable sales, engine-risk score, ownership cost, inspection checklist, and a negotiation script. If you're about to buy a specific boat, that's what justifies the $49.