Holding tank driving me nuts

[MickeyB]

Hey all. Starting week 2 of 4 out and about the loo is causing me grief. Ti be exact it is the holding tank.

All pipes clean and clamped. Undid then all. New seals etc on loo itself, jabsco.

I have an ss holding tank. Roughly square. Gravity out at the very bottom to sea cock. Clear (dont ask how I know).

Loo out into top of tank. Clear again.

Breather out of top of tank and over the side. Clear.

The tanknos situated so that I have to pull it out to do anything other than putting pipes on. Cannot see in and no inspection hatches

So what's the problem....

I think the tank is empty. Pump the loo and almost immediately it comes out the vent!!! 5 pumps Max?

Dowa anyone know the internal design of ss tanks - how can this be. I can only think that the vent pipe extends down to the bottom and something blocked...but the tank empties when I ask it.

Any advice appreciated.

Mike

[npmr]

Hi Mickey B,

Our 33i holding tank was a complete pest from day one. Not helped by various various marinas we rolled into, had no/broken pump out facilities. 

Much poking and stressing eventually discovered that the outlet to sea blocked inside the tank for a pastime.

Using a piece of narrow diameter hosepipe, pushed in from the pump-out hole in the deck, pushed up and down, rotated and generally agitating the contents vigorously, seemed to, eventually, cause a big gurgle and the perisher would empty loads of stuff. Not a good sight in a marina.

Paper of any sort is apparently, completely anathema to the system. Even what looks like really, really dissolvable stuff!

We have, after a couple of years, now cut a Y-valve into the system, with a new hole in the hull underwater and associated seacock, to bypass the tank, except when in marinas, when use of the heads is banned on our boat, except in cases of emergency.

As we rarely use a marina, this is not a problem for us.

We also put a Tec Tank external sensor on the tank, with a readout in the cabin, so we can see a problem looming, if we do use the tank.

[rene460]

Hi Mike, amazing how often we return to this topic, I think we should try and restart one of your earlier suggestions that we somehow between us, invent a better system.

I have no particular knowledge of the SS tank design, but I can’t see that it would be too different from the plastic tanks.  The hydraulic requirements are relatively simple.

I know you have had the boat for quite a while, and I am assuming that it used to work, so a new problem, rather than something from new.  Your comments imply that you have recently had the hoses off for cleaning and or replacement, and I assume the problem has appeared since that work.

The vent and the outlet from the toilet should go into the tank top, and neither should extend inside.

Obviously the outlet to seacock must be at the bottom, again without any internal projection.

The one which does extend down inside the tank is the pump out, which is intended for a vacuum pump on the jetty, so requires the pipe to extend down inside the tank in order to vacuum out the contents.  I am not suggesting that you suck on the deck outlet to test this one, but if you are at the jetty, and put some water in through the pump out connection, the jetty pump should then be able to remove that water.

I am wondering if in the hose cleaning and or replacement that you seem to have done, the vent and pump out connections have been inadvertently swapped.  This would explain the situation you have described, though I would have thought more pumps would be required.

Also, the vent outlet is below the top of the tank on mine.  It is essential that the vent hose does not have a low point loop that could accumulate a little, with the inevitable result as soon as you pump into the tank from the toilet.  This would then discharge after very few pumps, though I would have thought more than five, but would quickly clear if you keep pumping, at least until the next time.  From the highest point in the vent line, any contents should fall under gravity, either into the tank or out through the hull vent, with no low points for water etc to collect.

Otherwise it is a very mysterious observation.

Hi Npmr, our system seems to handle reasonable amounts of paper with the Jabsco manual pump.  We just use normal Supermarket paper, though we do select packages which claim to be suitable for septic tanks.  We use a chemical which claims to have a biological action to break down paper and solids, which seems to work.  As we are lake sailors, we always have to use the holding tank, and apart from the valves and seals being a regular maintenance job we have had no real problems.  I am sorry not to be able to offer more useful suggestions.

rene460

[lennies]

Mike, we have 34.2 also (2000 year).  We were having a hard time emptying the tank using the suction machine at the "pumpout station".  I bought a short piece of PVC pipe just small enough to slide down the deck fitting into the tank.  Then fixed a larger coupling onto one end of the pipe.  I use this to 'back flush' through the deck fitting with fresh water and a hose.  Sometimes the pump seems to struggle getting everything to come up and out and that's when I use the pipe.  Then it seems to work better.
    As to how it is put together, the tank has a pipe welded into it that goes almost to the bottom of the tank from the deck fitting.  When suction is applied to the deck fitting it sucks water and waste from the bottom of the tank until it gets to about a cm upon which it starts sucking air and the process stops.  If you want to get the last remaining wastewater out, you have to pour in more fresh water to dilute what's left and then suck that out.  We do this process about 3 times and call it good.
The other tank fittings are just a simple welded place to attach the appropriate hose.  If I remember correctly, they are all different size so you can't put anything onto the wrong fitting.
Also, I have used the pipe I made as a "dipstick", as the 'wet line' on the pipe when withdrawn shows me how much liquid is still remaining inside.  The pipe when fully inserted sticks out of the deck about 10cm.
hope this helps you.
Lennie

[reiner]

Hi,
for my understanding  the vent pipe should end at the top of the tank.
so if you fill it air will go out and during empty it air will come back.
If the vent pipe ends at the bottom under the water level,
during filling the pressure will increase and the level in the pipe goes up.
I think normally the vent has a smaller diameter, but are you sure that
no interchange with the suction pipe is possible?
I hope this could help good luck 
Reiner

[Mike]

Hi,

We have had problems with our 33i holding tank this year, and have had all of the symptoms in this thread. After a bit of research we found that the bottom of the tank can be covered in a hard silt which is similar to what you can find in the pump outlet pipe . We found that our suction outlet is almost directly above the tank outlet to the skin fitting, so with a bit of broddling with a cane I managed to clear the blockage. Unfortunately I too was also in a marina when I made this discovery.

The article we found suggested that a solution of white vinegar and water be left in the tank to dissolve the silt.

[rene460]

Hi Mike, I have often wondered about that part of the tank below the end of the tube for the pumpout nozzle.  Did the vinegar do the job?  And roughly how long did it take.

I remember one time putting a badly fouled joker valve and some other bits into a jar with some vinegar after servicing, and have the impression that several days later, there was no visible change to the deposits.  Perhaps I should have prodded around a bit with a stick to see if it had softened.

rene460

[billy]

Hi
I don't have a solution here but wonder if anyone has replaced sea toilet with a chemical Loo.
Our new (to us) SO32i has Loo and holding tank but next season on our home Lake there are no Pumpout facilities.
We used Chemical loo for 20yrs on our previous boat and I'm tempted to change.

Self pumping into drums is not a pleasant prospect!

The heads seems small for a typical Thetford type chemical loo?? Any thoughts?

[rene460]

Hi Billy,

Like you, I have many years of experience with the portable chemical toilets on small trailerable boats, if you consider 24 ft small when it is behind the car in a narrow street, that is.  (Took a wrong turn one day and found myself on a shared walkway in a busy suburban shopping centre.)

And I have also wondered whether it would be a reasonable option on the larger boat.  Certainly the maintenance is much easier, and they give fewer problems than the normal marine toilets.  

The main disadvantage is capacity.  The models with the small waste tank have to be emptied each two or three days, which gets a bit painful if your lakes are big enough for overnight trips, but no real problem if you only day sail.  The larger waste tanks are very heavy if you let them get too full.  And they all eventually have to be emptied.  So if there are no pump out stations, where do you empty them.  And it would become a pain if you sometimes escape the lake for a longer journey.

In the early days we used to take a small shovel and pick a suitable spot well away from the water to do what had to be done, but then pumping stations came in, and they all had provision to empty the portable ones as well.  We were usually back where we could find them every few days, but there were occasions when someone with a faster dingy would take a helper and several tanks back to town to be emptied.  It’s amazing what a friendly community will do for each other.

More recently, I have experienced the ones used in land based caravans.  The main issue with adapting these to a boat is how to access the cassette for emptying.  Don’t have the outside access that is available on a land based van.  And if you have the ones with the mascerator and pump out, I suspect you are back where you started.

 As MickeyB once said, there has to be a better solution, but I don’t yet know what it is.  But if you do a neat job with an eye to reversing the process if you or a future owner wish, I don’t see any real problem with the portable ones with the properly installed tie down clips.

Rene460

[MickeyB]

Sorry for starting a thread and then not returning.

So I have over the last week had every single pipe off. Literally. I have push pipes and things in all holes I could find. Nothing is stuck outside of the tank.

Something must be inside the tank that is taking up huge volume. Will go and buy 40 litres or so of coke cola and put it in, wait a few days then pump out and see what that delivers.

Thanks for all your help!

[so40gtb]

Gosh, we never had any holding tank issues with our SO34.2, but the awfully small tank on our SO40 was replaced the winter after we acquired the boat. The irony is that we could have put a tank of nearly any size in the SO34.2, but the best we could do in the SO40 was 75 liters.

[MickeyB]

So a final update for those who search this in the future.

After ascertaining that all pipes were clear, no blockages anywhere etc, I came to the conclusion that the only viable option was something stuck in the tank itself of very high volume.

So we decided to try and work out how much volume we had left.  To do this, I shut down the outlet pipe after ensuring she was empty (which of course she wasn't), and started pumping seawater through until it came out of the overflow pipe.  Counting the number of pumps and crude maths would allow me to work out roughly the magnitude of problem I have.

So I managed 10 pumps. Not many at all. We opened the outflow valve again and nothing came out.  So I assume that something is 'across' the higher portion of the tank and it slowly seeps through from top to bottom overnight - with solids seperated and making the problem worse again.

It was then that my alert wife said, the water coming out of the overflow was very brown and very chunky.  So we continued pumping, and sure enough, more and more chunks came out.  Now, being at the end of a 1000 other attempts, we thought one more wouldn't go amiss, and so I carried on pumping.  More and more chunks came out - logic being it is coming from somewhere.

(Forgot to mention that we are actually sailing at the moment - about 1/3 of way between Sicily and Malta on a lovelly calm day - we thought if moving at least we get some more suction on the holding tank)

For some reason I did carry on counting pumps.  At 150 ish, my wife said that what ever we were pumping was now changing consistancy, kind of like paper mache now.

At 400 (yes I need to regrease the plunger) all pressure from the pump vanished.  The overflow gurgled which it hadn't done before and a rather putrid bloom appeared behind us, for a good few minutes it poured out (sorry env).

So - we had something 'horizontal' in the tank, which blocked transmission downwards - and the workaround was pumping clean seawater over the top and out until it broke down enough for gravity/friction/neptune to assist.  I pumped a few hundred more I think to ensure clean, and half filled with valve closed, sloshed it around and emptied + repeat. 

Lets see how long it lasts.

[rene460]

Hi Mike, good to have a satisfactory end to the story.  Not something that is intuitive to guess.

I wonder if at some time in the past, it was left needing emptying for long enough that the solids formed a bridge and forever after only allowed the liquid to drain until the tank was essentially permanently full?  Do you normally use the tank and regularly pump out?  Or has your pattern changed recently.

Did you actually try your idea of the coke?  Or was it just the patient pumping that did it in the end?

rene460

[MickeyB]

Never got round to the coke as was on a month sailing trip at the time.  However, for wintering, we are going to do this around December time and see what happens.

We typically use the boat heavily - never out of use for more than 2 weeks absolute max in summer - but I think your thinking is roughly right.  We must have had something in there which 'dried' somehow in our heat here in Malta, resulting in a baffling mystery that would even test Sherlock Holmes.

Mike

[zaphod]

On my last boat I installed a macerator pump that worked beautifully. It sucked the tank out fully every time.

Our new boat is much simpler, with the overboard discharge being a simple ball valve that relies on gravity to empty the tank. While the simplicity of this setup is appealing, I am concerned that the drain could easily be blocked by something as insubstantial as a wad of toilet paper. Fortunately Jeanneau thoughtfully provided a cleanout/inspection port on the tank.

Mickeyb,

If your holding tank had an inspection port installed in it, troubleshooting and correcting the problem would have been a much quicker process. You should consider installing one for future use. It is likely the problem will happen again, and when it does you will be able to open the tank, shine a light in and see exactly what is going on. Ideally you should position the port above the bottom discharge port so you can use a stick to clear the blockage.

Installing the port would be a simple matter of buying a water tight deck plate and using the appropriate sized hole saw to cut the opening. A couple of hours work will save you many more hours of headache in the future.

[MickeyB]

Zaphod,  I was thinking about putting an access hole in, but my tank is stainless (no idea how thick).

Anyone know if i can get a large hole cutter for stainless and just drill?  Or does it require some serious equipment?

[zaphod]

Sept 16, 2019 6:20:37 GMT MickeyB said:

Zaphod,  I was thinking about putting an access hole in, but my tank is stainless (no idea how thick).

Anyone know if i can get a large hole cutter for stainless and just drill?  Or does it require some serious equipment?

I can't imagine the stainless is very thick. I have used regular carbide hole saws on stainless without too much trouble. Although a hole saw the size you will want could be a bit expensive, it is your best option. Another option would be use jig saw or rotozip cutter and cut it freehand which might be cheaper but harder to cut a clean hole.

[Don Reaves]

MickeyB,

I don't agree that this problem is likely to occur again, provided that the system gets regular use. After all, nobody has indicated that they have had the same problem. While an inspection port would be a good thing, if the problem never occurs again, it would be wasted effort. My recommendation would be to wait and see. If it happens again, that would be the time to consider installing a port.

Don

[sailbleu]

This has become ( for years now ) standard equipment in our boat .

www.aliexpress.com/item/32993472030.html?spm=a2g0o.productlist.0.0.375116d5OdZw31&algo_pvid=3a13d699-7795-498a-981f-9c6ebefd3be1&algo_expid=3a13d699-7795-498a-981f-9c6ebefd3be1-13&btsid=90a8a6ea-ef16-41ab-b40c-8dd93b9f8808&ws_ab_test=searchweb0_0,searchweb201602_9,searchweb201603_55

Mine is slightly different , more robust and has a removable display that works through wifi , but the functionality is similar .
I've used it on many occasion to track small parts in dark inaccessible corners of the bilge , and with the camera itself being waterproof I also use it to check the propellor for plastic bags , fish lines or nets that get caught whilst sailing . No rarity in the Med.
And yes , I even checked the inner state of my holding tank through the evac deckhole with it , build in leds as you know .

Regards