I'm sitting in Rockland on a mooring and it's not bad right now. I use my propane heater to take the chill off in the morning, but I'd suspect it would become an issue when it is really cold. If you were in a slip and could use an electric heater or have easy access to propane I would think it was do-able. Even though the season is really short compared to more southernly latitudes, Maine is a great place to cruise and I would think you would enjoy it greatly. Get a copy of A Cruising Guide to the Maine Coast, it's a great resource for any boat owner in or contemplating a visit to Maine.