How to check if a used boat is stolen before you buy

Compare the hull identification number on the transom with the title and registration, character by character. Decode it to confirm it matches the builder and model year in the advert. Then look hard at the plate itself: a number that is missing, ground down, painted over or riveted back on ends the deal.

That covers most of it. The rest of this guide is the detail behind each step, two places the check gets skipped (Coast Guard documented boats and the trailer), and what to do when the numbers don't line up. Nothing here needs a surveyor. A phone camera, a pencil and a sheet of paper are enough.

Where is the HIN, and what does tampering look like?

Every boat built for sale carries two identical hull identification numbers. The Coast Guard's construction rule puts the primary one on the starboard outboard side of the transom, within two inches of the top of the transom, gunwale or hull-to-deck joint, whichever is lowest. A boat without a transom carries it on the starboard side aft, within a foot of the stern. Pontoon boats and catamarans with replaceable hulls carry it on the aft crossbeam, within a foot of the starboard hull. The duplicate goes somewhere hidden, inside the boat or under a fitting (33 CFR 181.29).

The same rule says how the number has to be attached, and that tells you what tampering looks like. It must be carved, stamped, molded or bonded on so that "alteration, removal, or replacement would be obvious." If it is on a separate plate, the plate has to be fastened so that taking it off would normally leave scarring. And it may not go on a part of the boat that can be removed.

Read against that rule, these are the things that should make you stop:

• No number at all where the rule says one should be, on a boat that looks factory built.
• Fresh filler, gelcoat or paint over the number or around it, on a transom that is weathered everywhere else.
• A plate held on by new screws or pop rivets, or a plate with clean, unscarred hull around it. The rule expects removal to leave a mark, so a plate that looks easy to swap is worth asking about.
• Characters that do not line up, differ in depth or style, or look stamped by hand into a factory molding.
• A number on a removable part, such as a bolted-on swim platform or a motor bracket.
• A primary and duplicate that disagree, or a duplicate nobody can find. Look for it yourself before you ask.

States treat this seriously, and some put the risk on the buyer as well as the person who did the grinding. Washington makes it unlawful for anyone to destroy, remove, alter, cover or deface a HIN (WAC 308-93-280). Florida goes further: it is a third-degree felony to knowingly buy, receive or possess a vessel whose assigned number has been altered, removed, destroyed, covered or defaced (Fla. Stat. 328.07). Those are two examples. Your own state's law is the one that applies to you, but neither of these lets "the seller said it was fine" stand in for checking.

How do you match the HIN to the title and registration?

Photograph the transom number, then put the title and the registration card next to it and read all three one character at a time. The Coast Guard's guidance to state agencies puts the stakes plainly: "Entering even one character incorrectly causes you to alter the boat's identity entirely" (USCG HIN guidance for states). An honest typo on a title is fixable at the agency, but it is the seller's fix, and it should happen before money moves.

A pencil rubbing is worth taking as well as the photo. Florida's own form for certifying a vessel's HIN tells owners to lay the paper over the number and rub lightly with a lead pencil (FLHSMV form HSMV 87183). A rubbing picks up characters a photo flattens out, and it shows you whether the stamping is even. The same Coast Guard page lists the ways a state may verify a HIN when you register the boat, including pencil tracings, photographs, a physical inspection by a state official and a check of the National Insurance Crime Bureau's database. In other words, the number will get checked at registration whether or not you check it first. Checking it first just means the problem is found before you have paid.

Then check that the number belongs to the boat in the advert. The first three characters are the builder's code and the last four carry the certification date and the model year, so decode the HIN and compare it to the listing (33 CFR 181.25). A hull that decodes to a different builder, or a model year that does not fit the boat in front of you, needs an explanation. One more rule is worth knowing here: nobody may assign the same HIN to more than one boat (33 CFR 181.23). If the number on this transom also shows up in another listing on a different boat, at least one of them is wrong.

Last, match the names. The owner on the title and registration should be the person selling, and their driver's license should say so. Whether your state titles this boat at all depends on its length, age and the state, and the state-by-state title requirements say which case you are in. If the seller has no title to show you, what "no title" really means on a used boat sorts the harmless cases from the ones that are not.

What if the boat is documented with the Coast Guard?

Bigger boats can skip the state title. Any vessel of at least five net tons, wholly owned by U.S. citizens, is eligible for federal documentation (46 CFR 67.5), and a documented boat carries an official number rather than relying on a state title for proof of ownership. A small trailer boat will not get there, but a larger cruiser can, so ask the seller directly whether the boat is documented.

Two public records cover documented boats:

• The Coast Guard's PSIX vessel search. The Port State Information Exchange search takes a vessel name, call sign or hull identification number. Check that the name, number and particulars it returns match what you are being shown.
• The Abstract of Title. Any person may ask the National Vessel Documentation Center for a General Index or Abstract of Title on a vessel (46 CFR 67.301). The Coast Guard sends ownership questions about documented vessels to the NVDC and lists the abstract at $25 per vessel (USCG documentation contacts, checked October 20, 2026). It takes longer than a phone search, so on an expensive boat, order it before you agree a price rather than on the day.

The NVDC will not release information protected under the Privacy Act, so do not expect a full owner profile. You do not need one. What you need is for the record and the seller's paperwork to tell the same story.

Is the trailer titled separately?

Often, yes. In many states the trailer is its own titled or registered vehicle with its own VIN on the frame. Florida, for example, requires a title for trailers of 2,000 pounds or more and exempts lighter ones (FLHSMV titles). Thresholds differ from state to state, so check the rule where you will register it.

Treat the trailer as a second purchase and run the same check on it. Find the VIN on the tongue or frame, compare it to the trailer's own title or registration, and make sure the name matches the seller. A boat with clean paperwork sitting on a trailer with none is a common way to end up owning one thing and holding papers for another. The physical side of the trailer is covered in the trailer checks before you buy. Write the motor's serial number on the bill of sale as well, so every part of the rig you pay for is named on paper.

Which seller behavior should stop the deal?

Paperwork catches most problems. How the seller handles your questions catches the rest. Walk away when:

Payment pressure, recycled photos and the move off Marketplace are their own set of warning signs, and the boat scam patterns on Facebook Marketplace covers each one with the check that settles it.

What should you do if something doesn't match?

Don't pay, don't sign and don't take the boat. A mismatch is not proof of theft, but under a law like Florida's, knowingly buying a boat with a defaced number is the buyer's crime too. Ask for an explanation in writing and see whether it can be checked.

Some mismatches have a legitimate answer that comes with paperwork. Washington assigns a new HIN at registration when the original was never affixed or has been altered, removed or defaced, and the department can authorize an owner to put the previous number back (WAC 308-93-280). Florida assigns numbers to homemade boats and to boats that never had a manufacturer's number, and a court can order a replacement number where the original is missing or altered (Fla. Stat. 328.07). A seller with a state-assigned number can show you the state's paperwork for it. A seller without that paperwork is asking you to take their word for it.

If what you find looks like a deliberately altered number, leave it to the people who can check it. Call the local police non-emergency line or your state's marine law enforcement, and give them your photos, the listing and the number you read. Florida's statute, for example, says a number that is not clearly displayed is probable cause for an officer to inspect the vessel to establish its true identity. Do not confront the seller. Your part ends at getting the details to someone who can look up the number.

The checks in one table

Every check above, where to do it, and what a failed result means. The rules cited are federal unless a state is named, and the state rows are examples rather than the law everywhere. Checked October 20, 2026.

This is general information about checking a used boat's identity, not legal advice. The rules that apply to you are your state's, and every rule named above links to its source so you can read it yourself.

Header photo by David McElwee on Pexels.