Holding tanks.

After a number of modifications the sewage holding tanks are now up to my liking. ‘Waratah’ will have two heads (= toilets, for those not familiar with the marine lingo), one forward, and one aft next to the master cabin. Each has a holding tank, to allow storage of sewage in waters where you can not just dump it overboard. The holding tanks are made of steel, and have a capacity of about 45 – 50 liters each.

Now when I sailed professionally as a marine engineer, I had to be able to fix whatever breaks down on a seagoing vessel. The jobs I hated most, was working on the sanitary systems. So for ‘Waratah’ I wanted a system which first of all has few components that can fail, and further is easy to maintain and repair. For the toilets I selected standard hand operated ones, which require little more regular maintenance than adding a bit of vegetable oil in the hand pump once every 1 – 2 weeks.

For the holding tanks I wanted a system without any pumps, because they are the biggest source of trouble. And to replace and repair them is literally a ‘shitty’ job. So I decided to place my holding tanks high, above the heeled waterline of the boat. In restricted areas, or in a marina, the sewage goes into the tank from the top. There is a discharge line at the bottom of the tank, with one valve at the tank, and one valve at the hull. Where dumping of the sewage is allowed, I simply open both valves, and gravity does the rest. If this line gets blocked, it is easy to unblock it by pushing a spring through it from the inspection cover. That way I don’t have to open hoses and connections inside the boat. Because THAT is really not a nice job.

The tanks can also be pumped out from a connection on deck. In unrestricted waters, the two discharge valves would be open, and the sewage coming from the toilets, would go through the tanks and straight down and overboard. Another advantage is that by placing the holding tanks that high, is that I don’t have to install a vented loop (which goes above the waterline) into the discharge line. Another source of failures, and bad smell.


About Stranded Mariner

Marine Engineer and passionate sailor and cruiser, working in the marine business in China.
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