I bought a new to me boat from out of state and will have to change the registration number. What is the safest/best way to remove the letters from the hull? Heat gun? Goof off? Let me know what worked best for you...thanks.

Rubbing alcohol will work, it's slow but doesn't hurt anything.

I use my wife's hair dryer, with a plastic window ice scraper. A heat gun is to hot.

3M Eraser wheel. You can buy one at your local body shop supply place.

Acetone

I've got some options now...4 posts with 4 different techniques to try.

Bring it to New York !

Goo gone might work?

If the numbers are self adhesive and the hull is straight gelcoat, heat them up with a hair drier and peel them off. Any remaining adhesive can be removed with Acetone. If the hull is painted, you can still use the hair drier, but use citrus cleaner to remove the adhesive.

If the numbers are painted on, use Easy Off Oven Cleaner.

Are they vinyl? If so, a little heat and a scraper to get the edge up then heat and peel. Acetone for the remaining residue and some wax afterwards.