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GMac · 11-07-2006, 23:23

I'm toying with the idea of fitting one of those toilet holding tanks you fit up high on a bulkhead by the loo and gravity feed the contents out when in deeper water.

I don't have the room, power to run or the desire to put some serious pumped number in anywhere else.

Anyone had any experiance with these? Specifically do they work.

Catamount · 12-07-2006, 03:25

I don't have any experience with this set up, although it is something I have been considering too. Some people will say that any openings into a waste holding tank should be through the top only, never out the bottom. I suppose we shouldn't ever drill any holes through the bottom of our boats, either. The one piece of advice I have heard is that you should have a valve at the opening at the bottom of the tank, so that you don't have waste standing in the hose between the tank and your seacock.

Regards,

swagman · 12-07-2006, 03:40

Hi,
We've this set up in each of two heads - came as standard items when we took delivery two yerars back.
Ours are both stainless and the base outlet for each is maybe 12 inces max from the seacock. No valve at the bottom of the tank as suggested by Tim above - but they are working just fine.
Cheers
JOHN

SkiprJohn · 12-07-2006, 18:02

Aloha All,
It sounds really interesting but I'm having a hard time conceptualizing what you are talking aout (how it is plumbed). Does anyone have a diagram?
Kind Regards, --John--

Catamount · 12-07-2006, 18:20

See these links for the "KISS Type III MSD holding tank system"

http://www.southwindssailing.com/art.../KISS0008.html

http://www.sailcopress.com/editorial%20MSD.htm

As I mentioned above, one addition to this system that I've seen recommended is a valve at the tank outlet so that you don't have waste standing in the hose between the tank and the seacock.

Regards,

coot · 12-07-2006, 23:28

I have a similar configuration. The waste tanks are above the waterline, have a drain in the bottom and there is no valve at the bottom of the tank.

There is a manual bilge pump under each tank for pumping it overboard. I suspect this clears the tank faster than gravity drain. I can pump it out so fast that I'm not really sure how long it takes... Just open the through-hull valve and crank the pump handle until you hear air bubbles outside. I guess it is maybe a minute?

I am not aware of any problems as result of this configuration -- no leaks, no permeation of the hose.

Pumping the tank overboard clears the tank so completely that nothing drips out when you remove the fitting from the bottom. (I discovered this when I was replacing a defective hose.; the hose was bad when it was installed, not as a result of this configuration.)

GMac · 12-07-2006, 23:34

All good so far.

I was thinking about putting mine about 3 feet above the loo so it would be well above the waterline hence drain well. No way do I want to have to poke and prod anything in there.

The loo is just a manual Jabsco so I'm hoping it will pump up that high. Anyone thinking I not thinking right :-)

Do I need that vent off the top? Anyone not got one and still works well?

**Alan Wheeler** · 13-07-2006, 00:04

No you have to have the vent GMac. The air has to go somewhere as you fill the contents. Otherwise something might hit the fan.

GMac · 13-07-2006, 00:18

Ahhrr.. good call. I did not think of that but can imagine the end result and it's all not good :-)

coot · 13-07-2006, 19:58

Quote:

Originally Posted by GMac

The loo is just a manual Jabsco so I'm hoping it will pump up that high. Anyone thinking I not thinking right :-)

The output hose in my system rises about 4 feet (~ 1.2 meters) above the base of the pump unit.

I find that I have to replace the joker valve about once a year or so. You can tell when it needs replacing because some of the liquid in the hose flows slowly back into the bowl. That is, I flush the head and then a couple hours later the water came back up a few inches. Fortunately, the hose does not hold enough fluid to fill the bowl, so it can't overflow.

I suggest keeping a few spare joker valves on hand. I haven't been able to find any Jabsco joker valves since June. (Not that I'm trying really hard, but it's the part of the head that most needs regular replacement, so you would think even West Marine could keep them in stock.)

Dreaming Yachtsman · 13-07-2006, 22:52

The original head installation on our Fountaine-Pajot included manual Jabsco pumps discharging to the tank positioned above the toilets. The tanks are slender so the bottom is about 1.2 m above the toilet while the top is closer to 2 m above. We had no problems with that set up but decided to upgrade both heads to Vacu-flush for other reasons, primarily to avoid the "natural" smell when flushing with stagnant seawater. There is no valve at the bottom of the tank but the run from the tank to hull valve is only about 6 inches (0.25 m) on one head and 3.2 ft (1 m) on the other.

Draining the tanks is accomplished rapidly by opening the ball valve at the hull fitting located just above the water line. The only problem we have had in two years with any part of this system is a small seepage under the hose clamp on the top connection to the discharge valve on one head.

If possible, plumb your discharge lines with PVC pipe to avoid odor seepage. No matter how good, any hose eventually will pass odor.

swagman · 14-07-2006, 06:29

Yup - can confirm the vent is vital in any holding tank. If you think about it the stuff that's carried bio-degrades, and in doing so heats up and generates gases.
No vent and you'll almost certainly end up with at least a burst pipe - and a messy cleanup.
JOHN

GMac · 14-07-2006, 17:49

OK and thanks all.

A vent is needed.
Don't leave 'things' in the discharge pipe. Valve at each end of pipe.
Maybe lower the tank a bit to stop those 'things' drifting back into the bowl.
Shape tank to minimise the 'things' getting stuck in the corners.
Flush system with something a few times a year.
All good and easy.

One more question:
Any idea how many litres to the 'flush' i.e. is a 15 litre (4 US Gal) tank big enough?
We have lots of deep water very close by 95% of the time so the storage time would be very short and usually 24 hrs would be max time required.
Crew generally 1 bloke who is good mates with the backstay, if you catch my drift, and 3 females (the spooky part)

shoosteer · 29-05-2008, 00:39

Hi, I've spent six years rebuilding a floating wreck and now have a lovely Ganely (5mm.steel hull & 3 &4mm.topsides) Snowbird 30, has 3 keels and is a magic pocket liveaboard. In NewZealand -Now base in the Bay of Islands NZ.
COMPRESSED AIR -- Holding Tank-- Shower under floor (6inches deep)drain tank-- ARE EVACUATED with the use of a small 12volt auto tyre pump. AND I can also pressurize the 350litre Deisol tank to make fuel line bleeding so so easy.
DISPLACEMENT PRESSURE is all that is required which = nearly no pressure.
40litre (approx10gals) over the side in 2 1/2 minutes
130litre holding tank-spotlessly empty in 9 minutes.
IT WORKS LIKE MAGIC
I carry a spare $25 NZD compressor.
I Have copied this idea off a larger yacht I had years ago
NO hair-gunge and muck blocking and clogging conventional pumps
ZERO maintenance and it has never failed on me ------------------------yet