Thanks fellas....no I'm talking FRP/GRP full tube. No Inflatable. Now that I think about it, perhaps a cardboard Sonotube as plug. West System epoxied and through-bolted to hull. Alternatively, wonder if a guy could use the tubes off of an old Avon Hypalon. Cut the soft floor out. Its just I see a pattern with PVC tubes failing prematurely, new tubes costing way too much, and attempted refits sent to the dumpster. Clear as mud?
BTW, I live 2 doors down from a fiberglass textile plant. Cheers