Re: Please recommend sailboat museums NE US
I loved Mystic and many of the other suggestions sound great, but if you're right in that area anyway, you have to see Plymouth Plantation.
It's not a boat museum, though it's about people who came in boats. Like Mystic, it's a re-created town. You're in early 17th century New England--right smack dab in it. Unlike the mid 19th century, whose architecture surrounds us day-to-day, it's so very foreign to us that everything you see is a first. And you can interact with people who are in character and so good at it that you feel like an intruder in their world. I'm hard to impress but I'd go again in a heartbeat.
Read N. Philbrick's "The Mayflower" first and your time-travelling.