I was talking to my Dad the other day and he told me when he was in the Navy on Guam, wwII, him an a buddy of his took a launch of somekind, about a 10 footer or so, they had a small gasoline engine pump in the bottom of the boat, my Pop held the "intake" hose over the side and his buddy held the "out take" hose over the stern and said it was quite effective. They spent the entire day "cruising" the harbor.