Just because you register it in NH, which you should because you will use it here, doesn't mean you can't get a Mass title.
I would not bother getting a Mass title because it will raise all kind of issues with Mass sales tax, but if the bank demands a Mass title as proof of ownership, you may be stuck because NH does not title boats.
Here is link on getting a Mass title on a boat bought in a non-title state.
http://www.mass.gov/dfwele/dle/instructionspage.htm
You may want to talk to a NH bank or see if your bank can set up a loan that doesn't require a title, it would be shame to have to pay Mass sales tax on a boat that never enters Mass.