How to Find Boat Hull ID Numbers

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Finding the hull identification number, or HIN, on your boat is a simple matter of walking to the right spot. The HIN isn't the state-issued number emblazoned on your boat's bow. Its location may vary slightly depending on the type of boat -- whether it has a transom or not, and if it has more than one hull. The HIN is always 12 characters long: the first three letters identify the manufacturer, the boat's serial number is next, followed by the four-digit date indicating when the hull was built. The law requires the numbers to be permanently attached to the vessel.

Inspect the starboard side of your boat's transom, about two inches from the top of the transom. The letters and numbers must be at least 1/4-inch high.

Move to the starboard side of the boat if you don't see the HIN on the transom. Look on the outside of starboard side. The HIN should be found not more than 1 foot from the stern and not more than 2 inches from the top of the hull's side, or the joint between the hull and the deck.

Move to the stern of a catamaran or trimaran and look on the after crossbeam. The HIN is located on the after crossbeam, within 1 foot of the point where the crossbeam attaches to the starboard hull.


  • The HIN's four-digit date code uses both letters and numbers. The first character represents the month; January is represented by the letter "A," February, by "B" and on through the letter "L." The second character of the date is the last number of the year the hull was built. The third and fourth characters are the last two numbers of the year the hull was built.
  • You boat's HIN is stamped or engraved on your boat in a second, secret location, to aid in identifying the boat should someone steal it.