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stoutwench 04-10-2007 03:05 PM

Holding tank location
 
I need to replace the small (3 gal) holding tank in my forward head. This is the largest rigid tank that will fit in the forward bilge. We want to increase the size of the holding tank and can think of two possible solutions:

a) flexible holding tank located in the same area in the bilge as the old one

b) place a rigid holding tank in a different location that is higher than the head outlet. We have several possible locations.

Has anyone had success with the flexible tanks?

What problems will I run into if I place the tank higher than the head outlet? Will the head pump get the "bi-product" to the tank?

Roger

sailingdog 04-10-2007 03:20 PM

Roger-

Going with a flexible tank is a really, really, really bad idea for a holding tank... Think of how bad the odor gets with a rigid tank, and then realize that flexible holding tanks are 10x worse and much more prone to leaking. Part of the reason flexible bladder tanks are much worse, odor-wise, than fixed tanks is that they generally don't have any sort of vent installed in them... and they tend to produce more anaerobic, bad-smelling, bacteria than a fixed tank that is properly ventilated.

Placing the rigid tank higher than the head isn't all that big a deal. It just means that you'll have to use more water to flush the hoses clear of the nasty smelly stuff. It really depends on what kind of head you have and what kind of pump you have for it.

A Lavac, my personal recommendation for marine heads, wouldn't have much of an issue with it, since it uses a large diagphragm pump, which you could mount slightly higher than the tank's inlet.

A more traditional piston-type pump head will still be able to do this, provided the seals are in good shape.

One major advantage of putting the holding tank up high is that you can use gravity to empty it when you're at sea, provided it is above the waterline. :D

hellosailor 04-10-2007 03:35 PM

"Placing the rigid tank higher than the head isn't all that big a deal."
I'd be scared. The only thing preventing the sewage--or water--in the line from running back down into the bowl is the joker valve, and those always leak sooner or later. Unless you pump enough water to ensure there's just "clean" water in that line, it is coming back into the bowl. And if you pump that much water--there goes the extra capacity.<G>

Even with a siphon break in the line...I'm not sure there's anything to gain because of the excess water pumping through to go "uphill" and flush the line to the tank.

Can you perhaps raise the head, and install a holding tank under it? Gut the head, and install more holding tank across the head floor?

Raritan and a couple of the other tank makers have huge catalogs of standard sizes--that the chandleries just don't show or stock.

stoutwench 04-10-2007 03:45 PM

Thanks for the replies. Both of your comments make perfect sense.....which leaves me at the same place that I am now....a 3 gallon tank with a leak.

There are two seacocks under the head area and no room anywhere else for the tank.

Any other suggestions or innovative solutions will be appreciated!!!!

Roger

hellosailor 04-10-2007 03:50 PM

Well, if it's that small...urine is allowed overboard and a 5-gallon bucket with a lid, and some plastic bags and kitty litter, will accomodate the rest. If a second head isn't needed all the time, a compromise might be in order.

When you say "forward head" is there an aft head as well?

sailingdog 04-10-2007 03:52 PM

Roger-

Since it sounds like you have two heads aboard the boat, you could always just eliminate the forward holding tank altogether and use that head only on passages.. :D

TrueBlue 04-10-2007 04:01 PM

We have a 30 gal holding tank/or overboard discharge for our forward head - with only an overboard discharge option for the aft head. No solid wastes ever go in the aft head, unless offshore.

I have to admit - 3 gallons is not a good setup - since it does not hold more than a couple of flushes.

stoutwench 04-10-2007 04:06 PM

Quote:

Originally Posted by sailingdog
Roger-

Since it sounds like you have two heads aboard the boat, you could always just eliminate the forward holding tank altogether and use that head only on passages.. :D


Yes, there is a second head. Because the head is so small we only urinate into the frwd head. The aft head has a 15gal tank and is used for the other purposes. However, the aft head is my wifes personal space. If your married, you understand!!!! It would just be nice to have a larger tank since I must replace it anyway.

I use the bucket idea when single-handing.

Roger

stoutwench 04-10-2007 04:07 PM

Quote:

Originally Posted by TrueBlue
We have a 30 gal holding tank/or overboard discharge for our forward head - with only an overboard discharge option for the aft head. No solid wastes ever go in the aft head, unless offshore.
.

Exactly what we do but in reverse.

sailingdog 04-10-2007 04:11 PM

Yes, I've noticed that the women generally take over a lot of space and get things their way, or you end up suffering the consequences. If you're really worried about the higher holding tank, up forward, you could put either a check valve or a ball-valve into the hose to prevent a failure of the joker valve from dumping waste into the head.

Unless you've designed the holding tank poorly, an anti-siphon valve isn't needed, since the air vents in the holding tank will break any siphon effect, unless you've over-filled the holding tank, in which case—you're basically screwed anyways.


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