I think in this case a keel is a good thing. In my dreams I have an 18' square stern Chestnut just moving along with my 5 hp kicker about a hundred yards off shore and like Memaquay I hit a rock...
I'm guessing that other than beefing up support along the gunwales for the motor, it's for attaching ropes for towing and stuff. I think I will do something similar to mine, I really miss having a stern rope for towing, anchoring, lashing to trees, pulling a dead unicorn out of shallow water, that kind of thing.What is the structural or functional purpose of the thwart behind the stern seat?