Salty,
When you buy a boat you can deduct the interest on the loan as long as it is a secured loan. That is, the boat is held as collateral. This is for Federal taxes if you itemize, not NJ.
There are three other qualifications; you must be able to cook on it (portable stove or the like), sleep on it (cutty with v-berth acceptable) and use the bathroom on it (porta-potty acceptable). That is the way it was explained to me by my tax man when I was writing the interest off for taxes when I purchased mine until the loan was off.