The Importance of a Hull Identification Number

by | Monday, December 30, 2013 |

A Hull Identification Number (HIN) is a unique 12-digit number assigned to vessels by the manufacturer. It’s what distinguishes vessels from each other, much like a Social Security Number or a Vehicle Identification Number. All vessels must have an assigned HIN in accordance with Federal Regulation, Title 33 CFR 181, Subpart C.

Understanding the Hull Number Format

U.S. §181.25 explains that hull numbers are to be 12 characters long with no spaces or hyphens. Manufactures must assign the characters as follows:

  • First three characters – The first three characters are the manufacturer’s identification code.
  • Characters four to eight – The next five characters are the unique serial number that the manufacturer assigns. It can consist of any numeral or letter, provided it’s not an I, O, or Q.
  • Characters nine and 10 – These two characters represent the month and year of production. Months are written in an associated letter format, e.g., January is “A”, February is “B”, and so on. Only the last digit of the year of manufacture is used. So for a vessel manufactured in March of 2013, hull number characters nine and 10 would read “C3.”
  • The last two characters – The final two characters indicate the vessel model year, e.g., 13 for 2013.

Rules Regarding HIN Display

Manufactures must affix the hull numbers on each boat hull in characters that are no less than one-fourth of an inch high. It must be affixed in such a way that it would be obvious if someone attempted to alter, remove, or replace it.

The Code of Federal Regulations explains that the HIN can be:

  • “carved;
  • burned;
  • stamped;
  • embossed;
  • molded;
  • bonded; or
  • otherwise permanently affixed to the boat.”

The HIN number must also be placed in a second location, which is dependent upon the manufacture and the model of the vessel.

Why are hull numbers so important?

HINs serve several purposes. First, it’s the primary way a vessel is identified. It gives government agencies and ship owners a viable means to track the history of a vessel from the time it was manufactured. This can be very useful, for example, in the sale and purchase of a previously owned vessel.

Another reason hull numbers are so important is to assist in manufacturer recalls. If a manufacturer should ever recall a vessel or a vessel component, it will need vessels’ HINs to positively identify defects. It will also enable the manufacturer to contact you to inform you of any recalls.

Lastly, HINs are essential because you cannot register your vessel without one, nor can you apply for vessel certificate documentation which is a federal mandate.

Keeping Track of all Your Vessel’s Documentation

We understand how important it is for vessel owners to keep detailed, compliant records. At, we offer a unique selection of logbooks that will help you not only meet logging mandates, but also help your business operate smoothly.

If you’re unsure of what logbooks might pertain to your particular vessel, download our free Logbook Quick Reference Guide. For further questions, or to place your order, call today at (888) 468-3757.

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