In Rhode Island-
No sales tax ever if you physically moor
dock.marina or,it's just there!
You register there also.
Many domicile new
purchase yachts there for this reason-but vessel physically Must live there for this.
This not to say you can't sail it around the world either- you can!
Oh,and also you do NOT have to live there either !
Google -"John Kerry yacht tax Rhode Island"
Think Delaware has tax relief also.
All the Best