I'm building my own holding tank out of fiberglass to fit a spot on my boat. Fairly complex shape so can't use a stock tank. I was wondering if I could have the feed line into the tank down low in the tank, as this would hide it below the V-birth floor. Or do I have to have it feed in at the top. My out line would be a couple of inches below the in line. The Y valve is much higher then where the feed line would enter the tank. Any back flow issues that I should be considering or other issues???? Thanks for any help or suggestions!!
Line into a HOLDING TANK?
- Thread starter hodge3000
- Start date
There's a very good reason intake lines go to the top. Backfeed issues to the head itself come to mind. Like, for example, when you need to service the head and disconnect it. What reference material are you using for your "design?"
You are RIGHT!
Where it would sit would be parallel to the toilet or slightly above. So even though it might look a little unsightly I will plum into the tank at the top!
Tank is going to be constructed out of 7-10 layers of 12 oz. fiberglass using lots of Marine grade epoxy. I have seen this design in a number of commercial applications. Should be near as strong as the boat! Thanks for your advice!
Cheers!
Glen
Where it would sit would be parallel to the toilet or slightly above. So even though it might look a little unsightly I will plum into the tank at the top!
Tank is going to be constructed out of 7-10 layers of 12 oz. fiberglass using lots of Marine grade epoxy. I have seen this design in a number of commercial applications. Should be near as strong as the boat! Thanks for your advice!
Cheers!
Glen
Glen, it will be strong, fer sure. But it is subject permeation. I wouldn't count on the epoxy. There used to be a boatbuilder who would build in fiberglass tanks for fuel. It did not work so good unless you like the smell of diesel. Perhaps there are non-permeable coatings.
Also how is the waste going to exit the tank if the Y valve (And, thru hull?) are above the drain line. At least put a valve on the exit or you may end up with a s**t fire hose some day. I guess it can be pumped out but you'll want a self priming pump - probably a diaphragm type. Macerator pumps do not like to run dry.
Remember you'll need a venting system. See Peggie Hall's book Get Rid Of Boat Odors
I've sailed on a couple of 30/30's. Very PHRF friendly in light air.
Also how is the waste going to exit the tank if the Y valve (And, thru hull?) are above the drain line. At least put a valve on the exit or you may end up with a s**t fire hose some day. I guess it can be pumped out but you'll want a self priming pump - probably a diaphragm type. Macerator pumps do not like to run dry.
Remember you'll need a venting system. See Peggie Hall's book Get Rid Of Boat Odors
I've sailed on a couple of 30/30's. Very PHRF friendly in light air.
For very good reasons most modern holding tanks have ALL fittings on the top. The drains are dip tubes that reach within 1/2 inch of the bottom of the tank.
The BEST tank I have used has the input AND output going into the top of the tank. NO way to leak!!
Good luck
Greg
Good luck
Greg
Have you checked out Ronco Plastics Ronco Plastics Marine Catalog as source for a tank? They build TOP quality thick-walled rotomolded water and waste tanks for a very reasonable price (even better when you order it through the sbo.com online store) and have more than 400 shapes and sizes, over 100 of which are non-rectangular...and they install fittings in the quantities, sizes and locations specified by the customer when they make the tank. I'll bet a nickel you can find one that'll fit your space!
I would NOT use polyester resin as it permeates.. (the reason for hull blisters)
But using epoxy you could have much better sucess...
Roto molded tanks and even a good quality custom welded plastic tank would be as affordable if not more so, especially on the welded plastic as they only have to cut the shapes and then weld them together. No special forms to build..
if you have the room, which very few of us do, an inlet into the top side of the tank, and an outlet also in the top of the tank with a snorkle tube going to the bottom is the most secure and probably the best... even though there may always be an inch or so of effluent in there that cant be pumped out, if you ever have to work on the tank ot plumbing, you wont have the same issue that some have with the oulet at the bottom corner... (when its open while working on it, the small amount of fluid gets out into the boat, or if there is ever a leak in a discharge line, it will leak into the boat)
But i think a bottom outlet is the most common because its the easiest and there is usually enough room for it there.
I have a custom fit welded plastic tank with the inlet coming in the end at the top and the outlet going out the same end at the bottom, and other than the poor initial welding job by some beginner, it works well since i removed it and had it rewelded....