I have a power boat with a small genset and A/C and I cruise the New England area you mention. I have never run the genset at anchor to keep the boat cool. If we get an occasional hot spell, we just don't go as like you we are retired and can generally go when we want to go.

I do appreciate the desire for A/C while at the dock. Marinas are usually tucked in someplace out of the wind and your boat will probably not be oriented for the wind to flow down the hatches, so it gets hot. So install A/C and use it on shorepower only.

Charging batteries can be done on the hook with a solar panel installation a lot cheaper than with a genset. Look into a pair of lightweight, flexible solar panels that you can sew onto your bimini like these: http://www.amazon.com/Renogy%C2%AE-Monocrystalline-Bendable-Solar-Panel/dp/B00IK19VF6/ref=sr_1_1?ie=UTF8&qid=1426605621&sr=8-1&keywords=flexible+solar+panel. If you do it yourself you can install a 200 watt system for about $600 that will produce about 70 amp hours of power on a sunny day.

I just read your objections to solar. Installed on the outer sides of the bimini they are out of the way and at anchor with the mast centered they don't get much shading, just from the mast. They have gotten a lot cheaper. The Renology ones are about $200 each for 100 watts. I do agree that the old Unisolar flexible panels lost output over a few years. Don't know about the newer Renology panels. But at $400 a pair they are a lot cheaper than a genset even if you have to replace them after a few years.

David

David