Absolutely it is true. The boat is taxed where it resides and/or is registered. RI has no sales tax on boats. A couple of caveats though. RI has a very high annual registration
fee you will have to pay, and they also charge you to have your head
inspected and then you get to have a giant ugly sticker plastered on the stern of your boat. It is also expensive and sometimes difficult to obtain dockage or a mooring
in RI. New York
is particularly aggressive about trying to tax you on the boat, so don't be surprised if they claim you owe the tax, particularly if you document the boat with a NY hailing port. Be prepared with paperwork to demonstrate when and where you purchased the boat, where it is docked or moored, and have all the receipts to prove it. If you are a NY resident theoretically you can't ever bring your boat into NY waters or they can claim you are "using" it in NY and hit you up for the sales tax.
Skipmac, you'd better be careful. The letter of the law is that if you purchased it in NY while you were a NY resident you are liable for the sales tax no matter where you keep the boat or how long it was in NY before you moved it.