The Redwing 18 from Chesapeake Marine Design fits many of my ideals for a Harbor cruiser / adventure craft. It can take electric power with the efficient shape of a launch. You can beach it, and it has berths. At 18 ft, it should sit inside most garages. It has a small cabin. I love traditional picnic launches, but I think Boston requires some protection in order to enjoy spring and fall, the most quiet and thus best seasons for boating. CMD claims it can be built for $5000 in materials, which brings it out of the far reaches of the price stratosphere, where most boats float. Pang. They have the one for sale whose construction was documented over 3 issues of wooden boat magazine. Redwing 18 – Boat Plans and Yacht Designs — Chesapeake Marine Design.
UPDATE: CMD also wrote up a nice summary of choices in electric boat hull shape choices. Check out the PDF.