HT Vent

[memiller279]

So I was looking around for an old thread and couldn't find it despite numerous searches.

I am building a fiberglass holding tank (around 25 gallons) and need to figure out a way to put a fitting in the tank to connect a vent hose to. Being on a sailboat I want to make sure that when the tank sloshes around everything stays on the inside of the tank.

The current wall thickness on the tank is about 1/4" + so tapping the tank would probably not create sufficient threads.

Thanks for all your input,
Mike

[motion30]

You could just use a try hull with the barb on the outside plastic or brass or ss If I were gonna thread the glass I would use a few more layers in that area maybe 4''x4'' patch

[peghall]

A li'l gadget called the Uniseal is the way to go UNISEAL (Scroll all the way through to learn how to use it and to get to the price list).

Drill your hole (at least 1" btw) insert the Uniseal according to directions..a piece of pvc pipe or a pvc elbow...and you have a vent fitting that WILL NOT LEAK. Btw...vent line should be no longer than 5' (shorter is better), straight as an arrow, and rise no more than 45 degrees. Vent thru-hull should be an open bulkhead fitting, NOT a "vent" fitting.

If you want to make sure the tank contents stay in the tank and can't spill of out the vent or run back to the bowl when you're heeled, put the vent and inlet fittings away from the hull, toward the centerline of the boat--preferably ON the top of the tank-- so that waste runs away from 'em on one tack, hoses are running uphill on the other.

Only hose I recommend is Trident 101 Trident Marine: Sanitation Hose A double walled rubber hose that's been on the market nearly 20 years without a single reported odor permeation failure.

If you need more help in spec'ing all this out, I'll be glad to help you do it. Meanwhile, if you haven't already starting building this tank, you might want to check out Ronco Plastics (no relation to the VegoMatic Ronco) Ronco Plastics They make TOP quality thick-walled (at least 3/8") rotomolded PE tanks for a VERY reasonable price and have more than 400 shapes and sizes, over 100 of which are non-rectangular. And they install fittings in the sizes and locations specified by the customer when they make the tank.

[memiller279]

Thanks for the info - I had looked at getting a roto-molded tank but the shape was far too unique so I had to build one (really, really wish I could've just ordered one).

Appreciate all the help,
Mike