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How many characters are in a boat's Hull Identification Number (HIN)?

12 characters, with no dashes or spaces.

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  1. 12 ✔
  2. 10
  3. 17

Why: 33 CFR 181.25 says a HIN has twelve characters with no slashes, hyphens or spaces. The first three are the maker's code and the last two show the model year.

Huh, didn't know that: Boats carry two identical HINs: one on the starboard side of the transom and a hidden duplicate inside.

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References

Answer: 12. 33 CFR 181.25 says a HIN has twelve characters with no slashes, hyphens or spaces. The first three are the maker's code and the last two show the model year.

  1. 33 CFR 181.25 Hull identification number format www.ecfr.gov/current/title-33/chapter-I/subchapter-S/part-181/subpart-C/section-181.25
    must consist of twelve characters, uninterrupted by slashes, hyphens, or spaces
    Checked 2026-10-09.
  2. 33 CFR 181.29 Hull identification number display www.ecfr.gov/current/title-33/chapter-I/subchapter-S/part-181/subpart-C/section-181.29
    The duplicate hull identification number must be affixed in an unexposed location on the interior of the boat or beneath a fitting or item of hardware.
    Checked 2026-10-09.

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