The last two characters of the HIN are the model year; characters 9 and 10 are the month and year the hull was actually built. Both are in the same 12-character number, and on a lot of boats they do not match — which is normal, not a defect.
Take the last four characters of the HIN. The first of those is a letter, A through L, giving the month of manufacture. The next is a single digit: the last digit of the build year. The final two digits are the model year.
Example, from a published Coast Guard record: RNK70395C202 ends “C202”. C is March; 2 gives a build year ending in 2; 02 is the model year — a Rinker hull built in March 2002 as a 2002 model. Where the build and model year agree like that, the boat was built in the first half of its own model year.
Boat manufacturers start building the next model year in the autumn, exactly as car makers do. A hull laid up in September, October or November is routinely badged as the following year's model. So a HIN ending “K819” means built November 2018, sold as a 2019 model. Neither number is wrong — they are answering different questions.
| Use | Which year is used |
|---|---|
| Resale value and pricing guides | Model year |
| Insurance quotes | Model year |
| Registration and titling | Model year, in most states |
| Recall eligibility | Build date — recalls run by production range |
| Warranty start | Usually date of first sale, not either HIN year |
The one that catches owners out is recalls. A recall campaign is defined by when hulls came off the line, so it is the build date — characters 9 and 10 — that decides whether a specific boat is affected, regardless of what model year is on the title.
Older hulls use the reversed format: two digits of year followed by two digits of month, and no separate model year. A HIN ending “8103” is March 1981. Only 1972 through 1984 are valid under those rules, so a four-digit date block outside that window means the number has been misread.
If the title says one model year and the HIN decodes to another, the HIN is the physical evidence and the paperwork is the claim — but do not assume fraud. Clerical errors at registration are common, especially on boats titled in the autumn. Get it corrected before selling, because a buyer running the same check will find the same discrepancy and it will cost you either the sale or the price.
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 checkThe full character-by-character breakdown covers the other eight characters. What is a HIN explains what else the number is tied to.