Fitting a holding tank
Neil Fuller only narrowly avoided disaster designing and installing his holding tank
PBO reader designs and fits his own heads holding tank
My Westerly Konsort Koto was built in 1980 and featured a loo outlet connected direct to the sea via a 11∕2in Blakes seacock. But having decided to join the Emsworth Cruising Association summer cruise to Holland, we definitely required some means of retaining black water and being able to dispose of it via pump-out, so a holding tank was needed.
I looked on the Westerly Owners’ Association (WOA) website and elsewhere for articles about fitting a tank to a Konsort and found plenty of inspiration, including one owner who ended up fitting his tank in the bow beneath the water tank. That all looked a bit complicated to me, so in the end I decided to design my own.
The cupboard above and behind the loo seemed the ideal location for the tank, but
it would only accommodate a 30lt tank, which seemed a bit small for my liking. However, by moving the cupboard frontage so it ran parallel to the cabin side, rather than at right angles to the bulkheads, I could fit a 70lt tank, which sounded a much more practical size.
I spent a long time measuring everything and when I double checked it all looked good. It was only when I made a mock-up of the tank in cardboard that I discovered it was actually too big to get through the heads door – something I hadn’t thought to measure!
Having recovered from the ribbing doled out by friends in the marina, it was back to the drawing board. I had to reduce the size down to a 50lt tank which is about as small as I would want to go. This time the cardboard mock-up did go through all the necessary apertures (just). I am just glad I
found my mistake when I did.
Once happy, I drafted up the tank in detail using the Microsoft Visio programme I had on my computer.
I then committed myself and ordered a custom tank plus all fittings needed from Tek-Tanks. I looked into some cheaper options, but I went with the company that is well known and the product quality and service were excellent. I supplied my scale diagram to Tek-Tanks who converted it to a proper CAD diagram with all the elevations and a perspective view that you then have to approve. That way it’s your fault if it is not correct!
I took out the old, impractical sliding sink from behind the loo which made way for an outlet valve, in this case a TruDesign plastic ball valve (38mm). The top of the tank had connections for the loo (38mm), breather vent (38mm), pump out (50mm