The Marine Head version 1.0 on Talmid is about to receive a much needed upgrade. Since day one the water level in the bowl would gradually over time rise to 1/2″ shy of the rim.  To counteract this annoyance I was compelled to shut the seawater inlet at the thru-hull; a good practice for times left unattended but a royal pain for after each use as it involves latching the privacy door out of the way, lifting up a floor panel setting it aside and then swinging a stiff awkwardly located handle 90 degrees. A bucket up on deck would be easier. Keep in mind that the reverse procedure (opening) is also required before use every time and sometimes in the darkness.

Reason? The rim happens to be near sea level which is too close for comfort. When the boat heels or moves about its axis in a seaway the contents would slosh out. Talmid wasn’t going to sink but nevertheless; water in the bilge…

I mistakenly believed that the tight fitting clearances of the rubber seawater intake pump impeller would be enough to halt this perpetual “running toilet”. So, a restoration kit was ordered but this rejuvenation was not a cure.  An engineered fix is required.

Version 1.5 will be the addition of a vented loop for the inlet. As it stands, outside water pressure has a direct equalization path to the bowl interruptible only by the manual seacock method.  Adding a bend to the inlet line and mounting that bend ABOVE the outside water level is the proper solution. v1.5

But hold on; the new loop may not work because of the siphon principle. As a prevention I will have to include a siphon break. That is the purpose of the [diagramed] gizmo mounted at the apex of the loop. It is an electrically actuated solenoid which allows external air to enter the loop forming an air lock.  Water ingress is cleverly blocked by the laws of fluid dynamics. The work of gravity will allow the water to fall away — the suction broken by atmospheric pressure.

The electric push-to-flush button is parallel wired to energize the solenoid which simultaneously actuates the vent closed, and runs the seawater intake pump. The seawater pump is self-priming so the air pocket previously introduced via the vent loop openstate will not impede.

Can’t wait to see if the fix works version 1.5 working properly.