No, the annual excise/use tax on the boat is set by the town that the boat is kept in. Where I keep my boat, the fee is based on the length and age of the boat and has very little to do with the value of the boat. You're confusing the annual use/excise taxes for the one-time SALES TAX, which btw, is now 6.25%, not 5%.
I now understand the tax you are paying, which is based on the ownership of personal property, not the purchase of it.
I'm not confused with the use/sales tax. If you stay in MA long enough, they want use tax in excess of the sales tax you paid when you bought the boat. Since I'm in RI, I paid none. Therefore, I have to be sure not to stay in MA long enough to trigger their use tax. One time or not, I'll bet it is 100 times the annual excise/use/registration fees. I couldn't care less that they don't have a time triggered registration fee. By comparison, it would be peanuts.