RE: Good motor for SV 27?
That's not enough foam to keep it afloat with 12 cells. If you're luck enough to also have an air bubble in the bow when it goes down, that helps that puny piece of foam keep the boat afloat. Otherwise it WILL sink.
Doubt it? Take your boat to the lake, Have it loaded with the batteries inside (or equal weight) Fill the hull with water, and tell me what happens.