1. How do the foot pumps that work well compare in weight to hand pumps?

2. There is a potential safety issue with electric pumps and lead/acid batteries (which is what most car, motorcycle and marine batteries are). When the acid hits sea water, it produces chlorine gas, which is lethal. A marine store salesman said it has been an issue in many marine incidents.

You can try to keep the battery in a sealed compartment, but you are playing with your life.

He said most personal watercraft, which sometimes flip, use sealed gel cell batteries, because they leak less acid, but they are pricey.

BTW, auto and motorcycle batteries are not deep cycle marine batteries - lifetime will be very short if the pump is used much.

3. I've looked at built-in-battery powered bilge pumps (most use D cells). None of the ones I have found have an automatic shut-off switch, so you would have to open up your spray skirt (not always a good idea in conditions where you can flood), reach down to where the pump is, and turn it on and off.