Bulkhead holding tanks

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GMac

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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.
 
Got a tall upright gravity evacuation one (tank higher than pan) on our Benny ex factory and it worked OK from new, I now have to use pump outs as the gravity outlet blocks often. I intend to fit a diaphragm pump to the sea outlet to overcome that situation though.

David
 
I put one in the weekend before last!!. The fact the bottom of the tank is benched to a central drain means that most of the waste should easily be pumped out. I put a Vetus tank in and went for the 80ltr rather than the 60ltr as it has a significantly bigger surface area for the all important gaseous exchange. I also changed the 16mm vent that is provided to a 38mm one, again to aid ventilation and gaseous exchange.
The boat goes back in the water tomorrow, I will let you know how the tank works.

cheers,
Ben
 
Had one- dont now!! Problems with paper accumulating and blocking exit pipe at the seacock - narrowest point - whilst the seacock was closed. Would have been ok except for the paper tho'.
Messy business clearing it..........
 
Had a stainless tank as original equipment on the Dehler. Changed it this year for a plastic one, because the 'poo' in the tank ate through the stainless (admittedly over 10 years).

Was concerned that paper might not break up enough to go through under gravity, but so far no problems. I pump some jollop for portable toilets into the tank before leaving the boat, to dissolve any 'non-liquid' bits.
 
ST Article

There was an article in the ST a couple of years ago about fitting one. Unfortunately i lent my copy to someone and it did not come back. From memory, it was quite informative. Maybe someone could identify the issue it was in.
 
Gmac I posted a .hread about this very subject on 12 June this year. A very simple morning's work . Go to www.caktanks.co.uk and get a copy of their catalogue. They are about 1/5 the price of the well known manufacturer and very solid. THey also supply all the fittings etc. Gravity emptying works perfectly well. PM me if you need help.
 
Made myself a 50 litre tank and installed last year. It works fine, and no paper probs, as also fitted an electric mascerating head. Made tank with a 25mm vent and no odour issues detected to date.
 
All sounds good so far. Great answers all, Thanks.

I'm only looking at 15lt odd tank as there is always lots of deep water close by so we don't need lots of storage, mind you 3 girls on board....... Ahhggggg

I'm thinking of putting the tank about 3 feet above a std Jabsco manual to get lots of fall to the outlet. Hopefully the loo will pump up that high.

I think I'll put a valve on the bottom of the tank as well as the thru-hull one. The theory being things sitting inside the pipe may settle and then I'll need to poke and prod. This I don't want to do :-)

FYI - I had a quick word with the local Jabsco guy and he said, amongst other stuff, "don't be cunning and pour stuff like olive oil and other things down the loo to lubricate it and the seals, it just damages the seals. Now and again mix a bit of washine machine powder up in a bucket of water and pour that down. Works better and does a lot less internal damage"
I did not know that and would have though a light oil or similar would have been best, ya learn something new everyday.

Do I really need the vent up to the deck or wherever?
 
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I'm thinking of putting the tank about 3 feet above a std Jabsco manual to get lots of fall to the outlet. Hopefully the loo will pump up that high.

I think I'll put a valve on the bottom of the tank as well as the thru-hull one. The theory being things sitting inside the pipe may settle and then I'll need to poke and prod. This I don't want to do :-)

FYI - I had a quick word with the local Jabsco guy and he said, amongst other stuff, "don't be cunning and pour stuff like olive oil and other things down the loo to lubricate it and the seals, it just damages the seals. Now and again mix a bit of washine machine powder up in a bucket of water and pour that down. Works better and does a lot less internal damage"
I did not know that and would have though a light oil or similar would have been best, ya learn something new everyday.

Do I really need the vent up to the deck or wherever?

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I'm not a fan of this type of installation, for several reasons. But since you seem to be committed to it, I'll try to answer your questions.

Your toilet should be able to lift bowl contents 3'...but unless you pump enough times in the dry mode after use, you'll leave a lot of water in the line to run back down into your toilet. The joker valve in the toilet will slow down a flood, but isn't supposed to prevent slow seepage...and won't. And unless you use enough flush water after bowl contents to rinse the hose after using the toilet, it won't be water that runs back down, it'll be waste.

A shutoff valve in the discharge is a good idea...among other reasons, it will allow you to add water to the tank to flush out sludge accumulation in the bottom of the tank.

I don't know who told your local Jabsco guy that detergent lubricates a toilet pump, but he couldn't BE more wrong! Detergent doesn't lubricate, it just the opposite--it emulsifies and DISSOLVES oils, stripping any lubrication out of the pump...and powdered detergent will clog the pump unless it's completely dissolved before using it. Although petroleum products are damaging to the rubber bits in a toilet, mineral oil or vegetable are not...a tablespoon of either once a week will keep your toilet pumping smoothly and reduce wear of the rubber seals and o-rings. However, the best and easiest way to keep a toilet lubricated is to take the top off the pump and put a healthy squirt of thick Teflon grease into it...pump a few times and put the top back on. It's a 10 minute job that only needs to be done once a year, instead of the never ending weekly use of mineral or vegetablel oil. But it's your choice...however, you did NOT learn anything new from your local Jabsco guy, you got very bad advice!

And fnally, yes...all waste tanks MUST be vented, and MUST be vented to the outside of the boat, because methane is flammable, and the gasses--hydrogen sulfide and sulfur dioxide--generated by waste breakdown in an anaerobic environment are toxic, even lethal in high enough concentration.
 
I fitted one of these to my Norlin 34 a couple of weeks ago, along with a new Lavac. It works beautifully and is a huge improvement on the previous stinky setup, which had two pumps, 30 feet of hose, 2 diverter valves, and leaky bladder holding tank. THe bottom of the 15gal tank is only about 15" above static waterline and the top of the tank is above the WL at all angles of heel. I have a hose to the deck pumpout fitting teed into the discharge hose ( live on East Coast USA and this is required) . We don't put paper into the system (truly, nothing you haven't eaten or drunk goes in) but if we did the Henderson pump on the Lavac would cope with it no problem. When we're well heeled on stbd tack the bottom of the tank is just under the WL, forcing water up thru the discharge hose and into the tank, which cleans it out.
I know Peggie Hall is no fan either of Lavacs or gravity drain tanks but I have absolutely no regrets, apart from losing a bit of hanging locker space. So far it's proven to be kidproof and guestproof. If you PM me I'll send you a photo of the tank and plumbing.
 
Where did you get the idea that I'm not a fan of Lavac toilets? They're excellent toilets..one of only two toilets costing less than £500 (the other being the Raritan PH II) worth having IMO. It's just not necessarily the best choice if you have small children or frequent landlubber guests.

However, I've never been a fan of any system that sends everything to/through a tank except for boats on "no discharge" inland waters. If you're in waters where you can flush directly overboard, why store it aboard or have to mess with maintaining a tank?
 
Peggie - I seem to recall from posts on other forums that you thought the Lavac was confusing to landlubbers- - which you have just affirmed. Maybe you're right - but I've only had to explain it to a couple of them so far!
Agree with you about tanks etc - but when outside the 3 mile limit here or when on passage we'll have the discharge seacock open all the time (the vented tank will act as a siphon break) and everything will just pass thru the tank on its way overboard. I wanted as simple and foolproof a system as possible - one pump, no diverter valves, minimum hose run - and I think that short of a direct overboard discharge, no-tank setup ( ah, those were the days!), I've achieved it. Certainly has improved the quality of life on board.
 
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Agree with you about tanks etc - but when outside the 3 mile limit here or when on passage we'll have the discharge seacock open all the time (the vented tank will act as a siphon break) and everything will just pass thru the tank on its way overboard.

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Something you may have overlooked: Because flushes pass through the tank, leaving the tank "dry," the potential for sludge to accumulate in the tank is much greater than in a tank in which solids and TP can dissolve. And, unlike tanks that are pumped out, some of that sludge goes into the hose from the tank to the thru-hull. Unless you want problems, the thru-hull should be closed and the tank flooded with water to rinse flush it out several times a season...something that rarely occurs to anyone to till they start wondering why waste that should be going overboard isn't any more. So it's not QUITE as maintenance free as it appears in the first few weeks.

Note that I haven't said "don't do it"... only that I'm not a fan of this system. 'Cuz while there's nothing intrinsicly bad about it, it does have some issues that "conventional" tank installations don't. That no y-valves or pump is required is a trade off that isn't necessarily advantageous.
 
We designed ours so that the tank has the minimum height from the bowl and the sea water level is just on the tank base.

While sailing on port tack it gets a good sloshing out and has never blocked.

Also the vent is fitted with a carbon filter connected by 1/2" quick fit hose connectors. We can then connect the washdown sea water pump to the top of the tank when we need to clean it out. Only done it once to check the theory. This also allows the washing and filling of the filter to be done in the cockpit. Of all the solutions it has proved the most reliable.
 
All great stuff. I did not realise what is involved to store a poo :-)

The venting I did not think thru but now see it as needed.
Most of the time we can discharge direct over board but just want some storage if tucked up in a bay for a bit. We have rules saying no dischrge if inside 500mts from land or less than 5mts of water depth. We would get outside that very often and easily so small storage is all that is needed.
Its a fast race yacht so I don't want to load it with to much gear, besides I'm a simple chap and like simple things to operate :-)
Washing powder out as are petroleum products for lubrication.
I have the ablity to make my own tank so a tapered bottom to minimise and bits getting stuck in corners is now the plan.
Valve on bottom of tank and one on seacock to keep discharge pipe empty when not in use.
Flush stuff thru tank and system to clean it out a few times a year is good.
'Drift' from the tank back into the loo is still a work in progress. 1st thought is a non-return valve but I'm thinking it could jamb up and that's yuck. Maybe lower the tank.

I see a plan coming togeather.

great replies all , Thanks.
 
Neil, I'm not sure what type of filter you've put on the vent line, but the filters that are marketed for that purpose should never get wet. Not only does it render the charcoal useless for trapping odor, but the charcoal can swell, blocking the vent line. For that reason, vent line filters are no recommended for use on sailboats because heeling can spill tank contents into the vent line.

Vent line filters actually help to create the very problem they're sold to solve, because it's oxygen is the key to odor elimination...when organic matter breaks down aerobically (oxygenated), it doesn't stink...it's only when it breaks down anaerobically (without oxygen) that it can create noxious hydrogen sulfide gasses. A filter traps those outbound gasses, but it also prevents any inbound air into the tank, preventing the exchange of air through the vent line necessary for aerobic conditions in the tank, causing the contents to become anaerobic. So not only do they create the problem they're sold to solve, but they only last a year at most...are toast immediately if they get wet...and cost about about $65/ea. At least that's the price of the Dometic/SeaLand vent filters.

Gmac, you're wise to rule out a non-return valve....that's just asking for a clog. Since you plan to install a Lavac, your runback should be minimal 'cuz the vacuum SHOULD move the bowl contents the whole distance. It's people who have piston/cylinder toilets who are most likely to find whole bowlfuls of their waste back in the bowl, 'cuz 99% of 'em stop pumping as soon as bowl is empty--leaving the contents sitting in the line--or have never bothered to learn how to use the "dry" mode to do anything more than clear the last the water from the bowl and rarely if ever replace the joker valve....which, btw, should be replaced at least every 2 years...annually if you live aboard.
 
G'day Headmistress,
Oh yes I have been a very very naughty boy....... opps sorry, another bloody flash back :-)

I see your point with the filter, I did not think of that either. I'm surprised at all the little things in there just to trap people like me. Damn handy having all of you out there though, thanks. Imagine the poo (excude the pun) I could have gotten into without asking first.

Going to stay with the manual jabsco at this stage, very power limited and, to be honest, a lazy prick so if it an't broke it's not going to be fixed :-)

I've just come back from the boat and my outlet is basically just in front of the keel as low as it could go so I think the bottom of my holding tank could be very close to the same level as the bowl. Hopefully this will relieve pressure on my joker valve (having just read the manual to find out what a joker valve acutally is /forums/images/graemlins/smile.gif ) This would put the bottom of the tank just above waterline and approx 500mm above the thru hull.

I'm thinking I'm getting close but having been at that point before I'm happy to be told where I'm still going wrong /forums/images/graemlins/smile.gif
 
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G'day Headmistress,
I've just come back from the boat and my outlet is basically just in front of the keel as low as it could go so I think the bottom of my holding tank could be very close to the same level as the bowl. Hopefully this will relieve pressure on my joker valve (having just read the manual to find out what a joker valve acutally is /forums/images/graemlins/smile.gif ) This would put the bottom of the tank just above waterline and approx 500mm above the thru hull.

I'm thinking I'm getting close but having been at that point before I'm happy to be told where I'm still going wrong /forums/images/graemlins/smile.gif

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There MIGHT be a couple more places:

If the discharge thru-hull is forward of the toilet intake thru-hull, pumping the toilet can "recirculate" the outgoing flush through the toilet. For that reason, the toilet discharge--or in this type of installation, the tank discharge--should always be AFT of the toilet intake.

If the bottom of the tank will be at the same level as the bowl, that's likely to put it below the waterline--if not all the time, when you're heeled...and since water does insist on seeking its own level, that will allow sea water to flood the tank to the waterline. Not only will that mean the tank won't drain, but could even fill up with sea water while underway if the seacock is left open.

Btw (this has nothing to do with your tank installation...pertains to the toilet)...there IS a vented loop in the toilet intake? Essential any time a toilet is below waterline...'cuz without it, sea water will flood the toilet bowl if the tollet is left in the "wet" mode or the wet/dry valve fails (a VERY common problem in Jabsco toilets made in the last 7-8 years). Install one if there isn't one. It does NOT go in the line between the thru-hull and pump...the pump can't prime if it's there....it has to go between the pump and the bowl, to replace the short piece of hose the mfr uses to connect 'em, and needs to be at least 6-8" above waterline at any angle of heel.

Both seacocks should always be closed while away from the boat. They really should remain closed at all times except when actually in use...but boat builders have taken to putting seacocks in such inaccessible places as to make that so impractical as to be impossible.
 
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