After a couple close calls (shown below) I began thinking seriously about Larry's earlier suggestion that I install a battery and pump. I found a sealed 7 amp hour battery and a small solar panel at a flea market. The solar panel is mounted permanently on the aft seat and wired to the battery which is mounted in a plywood box high on the transom. I still check the boat after a downpour but the little bilge pump/battery/solar panel arrangement has worked fine keeping water levels under control.