sewage backs up into head when boat heeled
I installed a new holding tank under the V berth in my Catalina 27. The tank inlet is now above the outlet from the toilet. On a recent sail while heeled over the head started to fill from the holding tank.
Is the only solution to install a vented loop between the holding tank and head? Or, is replacing the joker valve enough to prevent backflow?
There is no overboard pumpout in the circuit, so siphoning of seawater is not a concern.
I would rather not have to drill a hole in the topsides for the vented loop to vent overboard. I am also concerned about how difficult it would be to empty the toilet completely with the vented loop in place, since the toilet doesn't seem to pump water through very well as it is.
Soggy 1975 Catalina 27 #2056