If you import a boat from Canada into the US that was built in Canada, there is no duty (NAFTA.) If it was built in the US than a US built returned goods entry must be made with customs. The import duty for boats built in most other countries like Taiwan or China is only 1.5%. If the Taiwan boat had been imported into Canada from the US in the past, and records were kept of the Entry Summary, and the sale was in the US not Canada, then the old Entry is still valid. If the sale was in Canada then the duty paid status is no longer valid.
There are new restrictions for engine emissions controls for boats built recently, most older boats can be imported.
Best to check with a customs broker so you know exactly what your situation will be.
Tucker Fallon CPYB