[TSOJOURNER]

The head on my 1967 CAL 25 is located on the port side. When I am heeled past 18 degrees on a Starboard tack the head overflows. Sewage in the holding tank comes back up through the toilet. Is there a one way valve that can be installed to prevent this situation. The current system is a type III. Waste goes from toilet to tank then either overboard or through a pumpout.

 

[RichH]

What you need is not a backflow preventer (check valve) as they commonly do not work after long term service. What is normally recommend is a ****vented loop**** , a discharge that goes approximately 3-4 ft. from the head/toilet straight up, then a vacuum breaker mounted at the top (will close when there is fluid being pumped, but will open when the pumping is stopped and allows air to enter) then a 3-4 ft vertical down pipe. ... thence to the holding tank. (Think of an inverted letter "U", with a air valve on the the top of the inverted "U"). Without the vented loop you risk siphoning the holding tank contents back through the toilet.... or risk sinking the boat if you are pumping overboard. Any time you have a discharge plumbing device overboard or into a tank you SHOULD discharge through a vented loop or you risk siphoning backwards to those areas below the water line of the boat.
:-0

 

[Denr]

You do not need to replumb your boat to solve this problem. Don''t you think that CAL would have figured out decades ago that a vented loop was necessary (sailboats heel when under way, what a revelation) for this application. Replace the JOKER valve in the head or get a complete rebuild kit and do the whole toilet. EOS