I tried the submerge thing with the boat tied down to trailer early on. I think the hose insides may be sucking shut. Why a 3/4 hose on the outside and 1 1/4 hose to sea pump?? With everybodys help we will get to the bottom of this. I will keep you posted. Would this be a good time for a external sea water pickup or would it benefit this setup? Thanks Gus