This is a series of posts which details the work which was required to outfit our boat with a holding tank for toilet waste. The project grew over time to include a refit and reconfiguration of the entire bathroom space.

With all the prep work out of the way (detailed in the first post), the tank mounted in place (the second post) we now get to the reassembly and the reconfiguration of the cabinetry.

An installation like this requires an insane amount of hose clamps. I mean really insane! I did an early sketch and estimated we would need about twenty but the finished installation required about 40 in the end!

We’ve taken the approach to use dual hose clamps on any hose connection where there is the potential for standing water in the hose which it fastens. This includes all thru-hull connections and all drainage connections from the tank and the flushing hoses. So it quickly adds up.

We needed two additional valves for the installation. One valve to select whether to flush the bowl contents to the waste tank or to flush it overboard. This of course so that in the event where the tank is full or blocked for some reason, the toilet can still be used.

Another valve was needed to be able to drain the contents of the tank overboard. This valve would sit below the tank and make it possible by the pure strength of gravity to empty the tank.

For both valves, we decided to go with the composite valves manufactured by Trudesign, a company based in Auckland, New Zealand. After having read up on customer reviews, it was easy to make a choice. Their waste direction selection valve is also really user-friendly in appearance and operation.

For the hoses, we went with a 38mm dual layer odour resistant sanitation hose for all wastewater connections. The hose is manufactured by Italian company Hoses Technology” and goes by the brand name of “Sanipomp/W”. This is a tough hose to cut and to bend (although it is marketed as flexible). It consists of an inner layer of black rubber and an outer shell of off-white rubber. A metal spiral runs through the length of the hose, making cutting the hose a tough job. With this toughness, however, comes the comfort that the hose will hold for at least five years of frequent use.

For the seawater flushing hoses, we went with a 19 mm transparent PVC-hose with a metal spiral running through it. This was a cost-effective and visually appealing choice. It does provide the comfort of being transparent which should help locate any potential blockage in the inlet.

I had carefully calculated the mounting location of the anti-siphon valves so that they would remain above the waterline under all circumstances. I took the opportunity to reconfigure also the location of the hand pump on the toilet to sit on the left side of the bowl. This made it possible to mount the anti-siphon valves and hose loops within the new cabinetry. I also splurged on a new Jabsco hand pump, replacing the older model.

As we neared the point where we would close up the cabinetry I also took the opportunity to mount the Gobius 4 Tank level monitor. Being able to monitor the tank level is a legal requirement in some countries, and the Gobius tank gauge does this using a vibration-type sensor mounted externally.

The Gobius has three sensors which need to be mounted at a height representing 1/4, 1/2 and 3/4 of the tank volume. To get these heights right, Gobius has an excellent tool on their website where you enter the tank dimensions, and it will tell you the heights. Brilliant!

Wiring the tank sensor to the main DC-panel required running some new cable ducts under the salon sofa.