I need a thing-a-ma-bob.

[TooCoys]

The mushroom for our water tank">fresh water tank vent line fell off long ago. I attempted to replace it with a nylon thru hull, but that didn't work.

The vent line itself has an end fitting that is a "cap" of sorts with a 90º female receptor. It appears to take 3/8" threads. This would be where the thru hull would screw into, except that the threads are smaller and finer than what a 1/2" thru hull has.

I was told by the marine supply store that this is commonly known as a "bulkhead fitting". It may also be what is known as a "breather vent". And of course they didn't have any. Surprisingly they suggested Tractor Supply as a possible place to find one.

I have searched online and I cannot find anything that looks like what came off, and I'm kind of searching blind. Even McMaster Carr doesn't seem to have anything.

Anyone have any idea what I'm looking for?

[SVTatia]

Hard to guess, but you don't necessarily need to replace the exact thing.
Google "boat tank vent" and choose the one most appropriate for your use. I have the vent hose attached to the vent barb.

[ranger58sb]

I think sometimes they're called vent caps, and often associated with venting for gas engines... but also used for freshwater and holding tank vents.

You might try searching online at West Marine, fisheries supply, boatoutfitters, etc.... or maybe even Amazon...

-Chris

[TooCoys]

Originally Posted by SVTatia

I have the vent hose attached to the vent barb.

I tried replacing the run of hose and going to the barb on a 1/2 thu hull, but the hole runs between the two halves of the hull and I'm working inside a 6x10" access panel. Running new hose is not an option, and I dont have enough length to connect to the barb, which would have been ideal.

[GordMay]

Tank Vents ➥ https://www.go2marine.com/shop-all-c...nts/tank-vents

[Sailmonkey]

I’m going to need a picture of the end of your vent hose.

[TooCoys]

Originally Posted by GordMay

Tank Vents ➥ https://www.go2marine.com/shop-all-c...nts/tank-vents

This is the fitting on the end of my vent hose. I think it's even the same patent number.

The only difference is that the part that screws into the hex looked more like a thru hull mushroom than this cylinder looking part.

[peghall]

Boat builders use the same vent thru-hull--one that's designed to keep sea water out of the fuel and fresh water tanks--for all tank vents, but it's a bad choice for the holding tank vent because it doesn't allow the air exchange needed to prevent odor, so you don't want to replace it with the same thing that fell off. What it should be is an open bulkhead or "mushroom" fitting (see photo)...the standard tank vent line is 5/8" Marelon, bronze or stainless steel are all good choices, nylon is not because nylon has no UV resistance...sunlight will turn it into powder.


There's another advantage to using bulkhead thru-hull...You can put a hose nozzle against it to back flush the vent line every time you wash the boat, preventing vent blockages.


--Peggie

[TooCoys]

Originally Posted by peghall

...the standard tank vent line is 5/8" Marelon, bronze or stainless steel are all good choices, nylon is not because nylon has no UV resistance...sunlight will turn it into powder.

Which is what happened to the first one. The remaining threads are nearly powder.

It is in fact a 5/8" line, however the threads on the back of a bulk head thru hull are too large a diameter to fit into the existing fitting, like I pictured above.

I think I'm going to remove the old vent fitting, but a 5/8" male to male hose connector in it, and cut a short section of hose to fit onto the back of a 1/2" thru hull and call it a day. It's only a vent line anyway.

[Sailnav]

I found a threaded end cap in the plumbing department and drilled vent holes in it, facing downward.

[jamhass]

Listen to Peggie. Your wife/GF will thank you. At least mine HATES head smells.

[TooCoys]

It’s not a holding tank vent, it’s a fresh water vent/overflow outlet.

[Disailor]

My fresh water tanks have a 1.5" threaded plug for filling. This plug has a hole drilled into the center of the top & a bicycle inflation valve (schraeder sp?) is screwed into the hole. One tank has a functioning valve the other has just the hole. Other than having to watch for when the tank is full, no issues.

[Nicholson58]

Originally Posted by GordMay

Tank Vents ➥ https://www.go2marine.com/shop-all-c...nts/tank-vents

I figured this was what the OP was describing. I found that these are properly designed for fuel tanks and the screen is a flame arrester. The warning is that insects, spiders can block the screen and cause problems. Otherwise OK.

I just used a Groco 1/2 inch bronze through hull with a hose barb.