Talking Heads

[Maurice55]

Here is a question to heads users.
I'm re-building this Dutch steel boat and thought, as space is precious, that I would build the holding tank as integral part of the boat. It's formed by the sides of the boat,the bottom(which is the floor) two part bulk-heads and the side-deck beeing the top. The filler hose connection is through the top (no opening at the bottom whatsoever !) Now, this means that there is an about 0.9m-3ft climb from the pan to the top, so if I use a normal sea- toilet I will use quite a lot of water to push the bowl content up this rise to be sure that it's resonably well flushed.So I was thinking that by using a "Lavac" type toilet with the pump mounted on the bulk-head near the top of the tank, with therefore the pump sucking more than pushing I might not need so much water.
Another idea is to use the vaccum system (needing the least water )but I'm not keen on an electric pump,ever heard of a hand one?
Any experiences, toughts, comments, ideas (low tech please) most apreciated .
Yours ......Maurice.

 

[Col]

I'm not sure about your pumping arrangement, but I certainly wouldn't use the inside of the hull as part of the tank.
A mate of mine runs a fabrication company, and often does work on our local river trip boats ( Byron would know the ones I mean)
He has just had to replace some of the hull plating due to corrosion from the waste tank, of the type you describe. Not sure if it is because there is some thing "corrosive" in the slurry, but I would fit a separate tank.

<A target="_blank" HREF=http://www.arweb.co.uk/argallery/colspics> Cols Picture Album</A>

 

[Maurice55]

I know that pumping s..t is not the most pleasant part of sailing, but we all do it.!
Is there no pump expert out there ? please....M.

 

[Guest]

had a similar design prob in my cat - the only place i could put the tank meant a rise of 3 ft vertically from the toilet outlet and then a gentle fall into the tank. worked fine - no more water consumed, but since there would be some efluent standing in the vertical pipe, i did pipe it with solid abs waste pipe, not flexible. this pipe is not porous (apparently, the process to make flexible means that all flexible pipe is slightly microporous). other advantage is that you can solvent weld the pipe together, so no jubilee clips and no poss of leaks from joins. result - toilet works and is absolutely smell free.

pipe and solvent came from b&q.

would strongly advise against making the hull into part of the tank. sewage is corrosive.

pm me if you want more details of piping system

 

[LadyInBed]

If you want to use a holding tank for ecological reasons, the problem becomes finding places to pump it out. If you don’t mind, and are able to pump to the sea, then there is no problem, so consider using a padded bladder in a top access tank. A good ecological alternative is a Portapotty, if you don’t mind the chore of carrying the holding tank to a convenience.
My boat came fitted with an electric flush toilet and the ability to switch it to the holding tank, but due to the volume of water the electric pump puts through the system, the holding tank soon becomes full.

 

[Guest]

There are all sorts of rumours about the enhanced corrosive properties of sh1t. In my experience the problem is no greater then that in an integral steel water tank. And (I know it' a bad way start a sentence!) the greatest area of concern on my part would be the condition of the hull plating immediately above the tank top, not the area of the tank interior, althought that can also be a problem due to lack of maintenance.. Many Dutch boats are built with no consideration of the effects of water traps on tank and stringer tops.

 

[petery]

I think it's TekTank's web site that points out that urine is so corrosive that it will effect even stainless steel - they suggest you look at the stainless urinals in public toilets! .. so heaven knows what it will do to other types of steel.

 

[spark]

I was part of a delivery crew of a big steel ketch last year, Dutch built. It had a grey water tank built into the top part of the keel as additional ballast. When the keel filled to near the top a float switch activated a discharge pump.

Somewhere off Cap Finnistere we found a lot of very nasty grey water sloshing around the floor of the engine room. Blockage in the pipe to the discharge pump. Stopped at a marina in Portugal and spent the best part of a day dismantling pipework in the engine room to gain access to the top of the grey water tank and then a very messy time cleaning it out. The blockage was being caused by large flakes of rust that had fallen away from the sides of the tank.

The boat was a luxury motor-sailer, built to a high spec and, from what I could see, very well finished. All of the other steel, inside and out, had been properly painted so there is no reason to assume the inside of the keel had been missed out from the original paint job. The boat was only 12 years old.

I would never, ever, use mild steel for a tank and definitely not build a tank onto the inside of a steel hull. Install a plastic tank that you can, if required, easily remove and replace. The only thing worse than having diluted jobbies leaking into the bilge would be having them leak out through a hole in the hull due to corrosive power of pee.

 

[Gunfleet]

Your experience sounds dire. However <<I would never, ever, use mild steel for a tank >> is a bit extreme. It just depends on the application. My C&N 26 is over 30 years old and has a galvanised freshwater tank in absolutely perfect condition.

 

[warrior40]

The Lavac, what else? The only loo to consider..

 

[Maurice55]

I thank you all for your interrest and concern.
On the corrosion level,I am quite aware that human waste, specialy mixed up and stored, is a very nasty piece of work indeed but I need to use the space I've got to the best, and a few coats of paint is thinner than anything else.So, through the large inspection hole in my tank (2ft x 2ft) I have sand blasted the inside to bare metal, applied 3 coats of Jotamastic 87, filleted the corners with epoxy filler and then applied 2 coats of Sikagard 62, which is probably equivalent to fitting a plastic bladder without the risk of chaffing ?. I still will have a plastic inspection hole in the top giving me visual access to the entire tank so if corrosion occur I still have the option to put a bladder in it.
My concern at the moment is more on finding a water thrifty way of pumping jobbies and wee-wees 3ft up with something simple, easily repairable and preferably non electric.........over to you..

 

[ArthurWood]

VacuFlush would be my recommendation. V. reliable, no smell except from vent pipe after being left unused for time, (charcoal filter is available),uses v. little water, but the vac pump is a bit noisy for a few seconds after flushing.

 

[LadyInBed]

Just put a toilet seat over the tank /forums/images/icons/smile.gif
Oh! I've already suggested that - Portapotty