John, just to point out, the excise tax and the sales/use tax in MA are two completely different things. The sales/use tax has the usual rules. Basically if you owned the boat outside of MA for the first six months you are OK. However, the excise tax is due for any boat moored in the Commonwealth, even ones where a sales tax has been paid. It's paid to the town not the State. It's also a very small amount, varying by the town tax rates, much much smaller than the sales/use tax.. hope that helps.
Steve McInnis