The cockpit on my 1980 O'day 25 drains slowly thru the thru-hull. It looks to be about 1&1/2" round, turns 90 degrees then turns 90 degrees again then out. I would take a look under the floor but I am a big guy and can't fit. Is there a back wash valve in the chamber that might be stuck closed or is it open thru and just plugged up? Would someone smaller than myself be able to disconnect from underneath and clean it out? What tools would be needed? I have tried running the garden hose thru it but with no luck. Thanks for any help, Jack