Holding tanks. We are going to have to fit one sometime, so......

Becky

Becky

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what advice can you give me? In particular, should I go for an easy-to-fit flexible tank, or would it be better to try and find or have made a rigid tank?

My fear with flexible tanks is that they may abrade through and leak, and that would be awful! With the rigid tanks, cost I believe will be considerable.

Second point; the waste pipe from the loo can eventually become impregnated with nasty odours. Can this happen with holding tanks?

We have 2 loos, should we fit tanks to both, or will just one suffice? And should we route washing-up and shower water to the holding tank, or can this be discharged overboard.

Our proposed cruising area will be N coast of France, down to theMed.Maybe later across the Atlantic when we have the boat bullet-proof (I really mean water-proof).
/forums/images/graemlins/grin.gif
 
Definately rigid rather than flexible - you'll never be able to fully empty it. To keep the plumbing simple I'd be inclined to connect one of the heads and in terms of sink waste water, it certainly makes sense to have them plumbed in - it'll ensure the poo tank is never left too long between emptying and will also reduce the possibility of crusty build ups inside the tank, resulting in extremely unpleasant 'chores'!!
 
I'll try to answer your questions one at a time:

"should I go for an easy-to-fit flexible tank, or would it be better to try and find or have made a rigid tank?"

Rigid...for several reasons, including those you mentioned. It's also MUCH harder to eliminate odor out the vent from a bladder because they're designed to hug the contents...no way to have flow of oxygen above the contents via the vent. And the tank MUST be vented--and vented to the outside of the hull, not inside the boat--if used for waste holding, for two reasons: 1. methane is flammable...2. waste produces gasses as it breaks down that can blow out fittings if it can't escape. Besides, a good quality bladder can cost MORE than a rigid tank. Tek-Tanks makes excellent quality plastic tanks and also includes an excellent (since it was adapted from my book, I think it is /forums/images/graemlins/smile.gif ) extensive article about tank installation and maintenance on their site at http://www.tek-tanks.com/Pages/frameset.htm


"the waste pipe from the loo can eventually become impregnated with nasty odours. Can this happen with holding tanks?"

No..at least not unless the tank is so flimsy that the walls can't even support of the weight of the contents. A plastic tank (and btw, plastic--polyethylene--is the ONLY recommended material for waste holding) that has a minimum wall thickness of at least 1/4" will not permeate.

"We have 2 loos, should we fit tanks to both, or will just one suffice?"

That depends on several factors. Are both loos used all the time, or is one a "guest" head used only occasionally? How much time do you expect to spend in waters where you'll be forced to use a tank? If the answers are "guest head" and "not very often," I'd put the tank on one--the LEAST-used toilet..better to be inconvenienced only occasionally than have to mess with maintaining y-valves etc on both, or even on the system you use mostly. If both toilets are used equally, you'll prob'ly want to put a tank on both. Depending upon where they're located--if a single tank can be located within about 6' or so of both, you might be able to get away with one larger tank for both loos...but not if the distance from one toilet is much further than that.

"And should we route washing-up and shower water to the holding tank, or can this be discharged overboard."

In most of the world gray water (galley, bath and shower water) can go directly overboard. However, there are a few places where it can't...and if the tree-huggers have their way, the number of those places will increase. But for now, don't worry about it. Besides, you'd need a separate tank for gray water anyway...plumbing sink and shower drains to a black water tank is not advised because e-coli and other harmful "critters" in waste can migrate into sinks and surrounding areas.
 
Because I haven't yet fitted a rigid tank in a boat. I have fitted two flexible ones. But mainly, when I don't know something, I use the resources available to me;namely those of you who may have done something like this before. Then I won't make the mistakes you may have done when learning how.
See?? /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
 
Thank you Peggie, that is exactly what I wanted to find out. I hoped that you would respond.
My partner and I will follow those recommendations.
Regards, Becky
 
From my experience, go with HeadMistress. Just one point, don't bother with a contents gauge. Everyone told me not to bother but I ignored the advice and paid £80 for it and it failed three months later. Probably gooed-up and I don't want to un-goo it /forums/images/graemlins/grin.gif
 
If it's only a clogged sender and not an electrical problem, it may not be hard to "ungoo". However, just 3 months is a bit short for the animal fats in waste to clog a sender...but it's worth a try anyway: Fill your tank with water to which you've added a mega-dose of heavy duty degreaser detergent. Go sailing and tack a lot to agitate...let it sit for a few days...then pump out or dump and rinse out the tank very thoroughly. If it is only "goo'd" that SHOULD ungoo it. If it doesn't, it's prob'ly not goo'd.

Problems of this sort aside, I do recommend a gauge of some kind... US and Canadian law requires a means of determining when the tank is at least 3/4 full...either accessible for visual inspection, or a gauge if not acessible for visual inspection. Whether ISO and EU rules will also require it remains to be seen. But whether they do or not, relying on the vent as overflow to let you know when the tank is full is a good way to clog up the vent...and that leads to problems you don't even want to think about.

My favorite gauge is the AcuGage, made here in the US by Snake River Electronics...the sender goes on the outside of the tank (any material except metal), so it never comes in contact the waste, and so can never become clogged. They just don't ever fail...I've seen 'em still in service after more than 15 years. And, it's relatively inexpensive...a system that can handle up to 4 tanks--water waste, and fuel--is only about £70 at discount...it doesn't way much, so airmail postage is minimal too. Check it out on the Snake River site : http://www.snake-river.org/ and at this online retailer: http://www.boatfix.com/elec/acugage.asp
 
[ QUOTE ]
Because I haven't yet fitted a rigid tank in a boat. I have fitted two flexible ones. But mainly, when I don't know something, I use the resources available to me;namely those of you who may have done something like this before. Then I won't make the mistakes you may have done when learning how.
See?? /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

[/ QUOTE ]

A wise man learns from his own mistakes...wise women learn from the mistakes of others. /forums/images/graemlins/laugh.gif /forums/images/graemlins/wink.gif
 
interesting topic.

What's the current view on 'sometime'. I see some stuff suggesting it might be next year (EU Directives).
 
[ QUOTE ]
interesting topic.

What's the current view on 'sometime'. I see some stuff suggesting it might be next year (EU Directives).

[/ QUOTE ]Where do you "see some stuff"? - please post links to this information or are you another scaremonger? /forums/images/graemlins/wink.gif
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hammer.thumb.gif
"Artificial intelligence is no match for natural stupidity"
 
Apparently the possibility of an EU Directive on holding tanks in UK was mentioned in PBO recently but there seems a complete lack of any backup information. I tried to research it myself afterwards including going to the RYA Cruising mob but drew a complete blank. Perhaps PBO should print a clarification (or even a retraction?!).
 
My Pedro has an excellent idea.If you can get a thro. hull fitting at an angle of approx.45degrees to the hull approx.2.5inches in dia. this automatically empties the holding tank when you go above 4kts due to venturi effect ,yes it does work it drops the level about a foot!!.When in harbour you can close the seacock, when you get going the seacock can be opened and it gets cleaned out again,could be difficult to fit on a f/glass boat as Pedro,s are steel.Why we worry about a bit of human dung I dont know, as ducks dont wear nappies!!.I would agree in a big marina it could be a problem.What they need to worry about is that a lot of narrow boat owners put formaldehyde in the holding tank to stop it smelling then pump out when they get on the canal,a lethal combination.
 
Even if the EU implement such a directive it will almost certainly be aimed at new boats, and would be unlikely to require retro-fitting. It would also allow a phasing in period before implementation.

Personally I think that holding tanks should be fitted. I must get around to finishing mine......
 
One small point which Peggie has mentioned in the past and which I ignored at my peril, is that of filters on the vent. Tek tanks et. al. sell these and seem to recommend them. Because of low freeboard etc., we have our vent on the coachroof, and decided to fit a charcoal filter to prevent noissome odours wafting along to the cockpit. Unfortunately a drop or two of rainwater found its way in over the winter and the filter collapsed blocking the vent entirely. This allowed a build up of said noissome odours until the tank was next used, when the pressure spat charcoal all over the deck, followed by the odours. IMHO a charcoal filter on the vent is counterproductive.
 
One important bit of advice. Leave a diagram and written instructions for the next person to buy your boat ! We have a holding tank and I can't for the life of me figure out how to empty it. ( Same s0dd1ng problem with the electrics ... ) /forums/images/graemlins/mad.gif
 
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We have a holding tank and I can't for the life of me figure out how to empty it. /forums/images/graemlins/mad.gif

[/ QUOTE ]

Is yours a rigid tank or a bladder? Regardless of which, have you traced the plumbing from the tank to find out what lines go where?

There SHOULD be a line into the tank from the toilet...a vent line to a fitting on the outside of the hull...and a discharge fitting that may or may not have a tee or y-valve in it--one side going to deck pumpout fitting marked "waste," the other side to a pump (manual or electric macerator) and then to a thru-hull/seacock. Or, there may be only one direct line to EITHER a deck pumpout fitting or to a pump and then the thru-hull.


Emptying the tank should be pretty straightforward...to pump out, connect the pumpout nozzle to the deck pumpout fitting, turn on the pump and watch the sight glass to know when it's sucked out all the contents.

To dump the tank at sea, the seacock must open and any y-valve aimed toward the pump...the seacock should be closed and the y-valve aimed toward the deck pumpout fitting to pump out.

To do either, make sure the tank isn't blocked...if it is, the pumpout or onboard pump will pull a vacuum, preventing anything from being pulled out.

So tell me why you haven't been able to empty the tank...so I can sort out why...
 
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