I am a Canadian and have sold a cdn registered boat in the
USA. However, I first had to
import it into the us and register as a us vessel. I had a
broker do the paperwork and I had to pay a small
import duty (amount depends where vessel was built and application of
current NAFTA agreement) and a brokerage fee. I was on
west coast and imported it into
Washington. When I sold the boat, the buyer would have had to pay
Washington state sales tax, so you may not save much. The other alternative is to take the boat out into international waters and complete the
sale and then return. This was quite common with sales of expensive mega yachts when BC had a thriving boat building industry.
Also, I think that some or all of the BC sales tax/GST is refundable if you remove the boat from BC. , but not sure. Anyways, it can be quite complicated and if the amount involved is significant, you should get expert
advice. Ie. iyacht brokersge or a document