The issue is the rail located directly above the pumpout opening. I ran into this problem the first time I tried to pumpout, where the pumpout facility's fittings were all too tall to work (interfered with the overhead railing). I managed to get the attendant (for $20.00) to borrow a tapered rubber 'cork-type' fitting from an adjacent boat repair facility. It has to be pushed into the boat's pumpout fitting by hand and held down tight the entire time while pumping to avoid any air leaks. It worked, barely, because it was still at an angle due to the stiff pumpout hose pressing against the rail. I was warned to hold down tight, and I noticed the attendants all moved back. LOL If the seal is lost or the level in the tank gets low and starts sucking air, the vacuum starts and stops while the hose pulsates rhythmically. Then the "sh#!" can backflow through the hose, pulsating with significant pressure (due to head pressure of the 'liquid' and air expansion from vacuum back to atmospheric) which may lead to a "Sh#! shower". Hope that makes sense.
I made 4 fittings of various configurations (2 like Brian B and Rworton described above) because I plan to travel to many locations. I made mine out of all black polypropylene material like the 1 1/4" pumpout fitting (for 'obvious' reasons?). I keep them in the propane locker. While test fitting them in the driveway, I accidently dropped one as it came unscrewed. That got me thinking.....will they float...NOPE! So I added floating keychain fobs to each (doesn't take much).
Now I can hardly wait to pump my "Sh#!" out. :ugeek:
Todd
