Holding tanks

[Zach]

PVC pipe is an intriguing idea!

A whole lot easier to find places to slide in a few tubes, rather than tearing apart the whole boat to add a tank. A fair bit of wasted space though...

[Delezynski]

Hint....

If you make one, PVC or other stuff, put the "IN", "out" and "vent" on the TOP! That is how our tank is and makes for NO LEAKS!

Greg

[Lancerbye]

the vent and the "in" are usually on top but the "out" will need an internal pipe going from the top to the bottom to be able to empty the tank.

[Zach]

I'm a little intrigued by the pipes idea, and setting them up vertically... above the water line with a valve/T to the outlet sea cock. The ability to gravity drain overboard... (Could have other dangerous gravity related results... but the plumbing maze would be reduced by miles...)

A dip tube inside would still be required for vacuum pump outs...

Sitting vertically, the gap between the pipes would allow for the head to tank line to nest in between making for a more compact installation too. Only one Y-valve...

[Zach]

Found a slick idea... this system does away with the Y-valve, and has the ability to link multiple tanks with only one dip tube... and it gravity drains. Southwinds - August 2000

Pretty sure I'd put a valve at the tank though... grin. There are few things less fun to mop out of the bilge...

Edit: I guess using hoses and fittings larger in diameter than the outlet of the head might allieviate some concerns of clogs too, or at least make the clogs easier to find. (Grin) Either a built in restricted section, or large enough diameter...

[Hud3]

A lot of cruisers I know have good things to say about Ronco plastic tanks. They make them in a lot of different shapes.

Marine Tanks - Ronco Plastics

[bmartinsen]

I checked into the prices for 12 pvc. Wow. The pipe wasn't bad but the end caps range between $160- $460 each. So I'm back to looking at square tanks and think
I can use a Todd tank if I can turn it on it's side( verticle) so holes are on top and build a siphon to remove waste. I don't want to relocate hole for removal. Anyone
done this?

[GordMay]

There should be no need to flip the holding tank on it’s side.

Goto:
Appendix 3.0 - Sewage Holding Tanks (Voluntary) | TP 1332 | Marine Safety

[bmartinsen]

Hi Gord
The space that I want to utilize is 20"wide x 16 deep x 30" high. Todd makes one like this but is designed to be 20 " L with the input, output and vents on the side.
1: doesn't fit this way.
2: can't put as much in
3: contents tend to plug vent easily when rocked or healed ( only have one hull. might be easier to add hull than holding tank

I thought if all holes where one top everything would be better.
I live on an island in the caribbean, nice but not enough boat stores.
Cheers

[Hud3]

Originally Posted by bmartinsen

... I live on an island in the caribbean, nice but not enough boat stores...

I know the feeling...

[Zach]

Bmartinsen:

Might want to call up the manufacturer and see if they'll do a one off for you. If the tank is rotomolded the holes and fittings are probably welded in after its molded. In any case they ought to be able to locate the fittings where you need them.

Zach

[ausieman]

Just thinking out loud here but would it be possible to fiberglass the ends of pipes over and maybe incorporate some fittings into this whilst at it.

[Lancerbye]

FG does not adhere to PVC very well but one can weld PVC and sheet PVC is readily available at Industrial Plastics. You use PVC rod and a high heat gun with a concentrating tip.

[Zach]

It is an interesting idea... Just use the PVC tube as a form and abandon it in place... a piece of polystyrene and carve it into a bowl... slap one on each end and glass the whole shooting match, drill a hole toss in some acetone and pour out the foam.

[Roy M]

Why not just build the whole tank out of plywood, coat it with epoxy, bolt the lid on (to allow access to the interior), and gain the advantage of more volume? All of this stuff about tubes just reduces the holding tank capacity, doesn't it? The tank in the picture fit into an unused space and provides about 20 gallons of storage. It is above waterline, so it can be discharged overboard without pumps, or alternatively removed via a deck mounted access for the sewage pump.