My solution to water backing up through the cockpit drain in my '76 M17 is a short piece of hose, slightly smaller than the drain, wrapped with duct tape for a snug fit. Jam the hose into the drain so a a couple of inches sticks out. This keeps water off the cockpit sole unless you're REALLY stern heavy, and, if you forget to pull it, you'll only get a couple of inches of water standing before it starts to drain.
Michael Towers M17 #226 _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats
