I am a long ways from putting a bilge pump in my kayak but I keep thinking about what a poster from Canada said about using toilet plungers for the pumps. It would seem that two of them mounted as combination foot braces that your feet rests on and at the same time also being two large volume pumps would be an ideal marriage. I am not sure how the pumps would work, but wouldn't the bilge line from the rubber plunger to the bilge have a one way check valve on the end of it, and the discharge water line have a one way check valve on its end also but working in reverse of the bilge valve.

John