thanks!!

If a NYS resident you're liable for use tax even if you paid a sales tax at the state you bought the boat. NY will usually give you credit for the sales tax you paid.
The important thing is, NY's use tax is due the moment you enter NY waters even 10 years after the purchase! There are no time limits.
Ronbo

I guess you have to pay even if you are less than 90 days in the state if you are a NY resident....

Beware, NY will collect. Don't ask me how I know.