Sounds like you have a P-15. Our 1980 model had a UV damaged/disintegrated
cockpit drain fitting as well. I replaced it with a 'SeaFit' Motorwell Drain
Tube. West Marine #307498. It's as close as you can come to the original
equipment drain tube. It was sort of a trick to install, but they're cheap
at two bucks a pop. Good luck...
Bill de Ment P-15 #1044 'Sukoshi'
Eagle, Idaho