Today I finished the project of replacing the sewer lines, joker valve and Y valve for the guest head. After our last trip the drain line has become clogged.

The Y valve is a bit of an obsolete item since it is designed to allow you to switch where the sewage goes, from directly overboard or to the holding tank. However since anywhere we boat in the US and Canada there is no where that you can legally pump overboard without the sewage going through the holding tank. In fact the US Coast Guard likes to see that Y valve locked or zip tied in the holding tank side rather than allowing people to pump overboard.

I considered just completely removing the Y valve and having a check valve that would just allow flow to the holding tank. The problem with that plan however was that I would then have an extra thru-hull drain with an open hose on the end of it. So I went with an exact replacement of what was there.

The guest toilet was at the point that it would not drain due to excess buildup int he Y-Valve and 1″ drainline to the Y-Valve.

Here is the diagram from the owners manual on the plumbing systems.

With this hose change and Y Valve change it has significantly improved the flow over what we have ever seen in the 4 years of using the boat. Next on to the other head to replace that y-valve.

Lesson learned, if you are buying older than about a 10 year old boat, I would suggest replacing these items, or at least comparing the flow rate on the toilet to one that has good flow.