Originally Posted by Bash
it's not high enough for a bilge pump. think about how much good that thru-hull will do once you've got water above the floor boards.
I don't get it. He's talking about a manual pump that will have check valves, and he is willing to add a loop, though it should have an anti-siphon valve. ABYC says to have an anti siphon loop and a seacock if your pump discharge is underwater.
If you're talking about pumping efficiency, if I've thought this through correctly, once you've displaced the air out of the hose I don't think it matters how deep the outlet is.