Holding Tank Vent

[Alan Peace]

Can any owner advise me of the size of the holding tank vent pipe on a 40.5 built in 1995. I'm not near my yacht at the moment so I can't just take a look. Also does anyone know the make and details of the skin fitting on the end of the vent pipe? Thanks in anticipation.

Regards, Alan Peace s/y Llamedos of Hyde

 

[Peggie Hall HeadMistress]

Can any owner advise me of the size of the holding tank vent pipe on a 40.5 built in 1995. I'm not near my yacht at the moment so I can't just take a look.

5/8" --1/6 cm--is the standard inner diameter for all tank vent lines...fuel, water, waste.

Also does anyone know the make and details of the skin fitting on the end of the vent pipe?

You call them skin fittings, we call them thru-hulls...It's most likely a generic that's also suitable for fuel vents...boat builders are fond of using the same type on all vents. Whatever it is, I'd replace it with a simple "bulkhead" or "mushroom" thru-hull (see photo)...this type, unlike "vent" thru-hulls, will allow you stick hose nozzle against it and back flush the vent line into the tank, preventing a vent line blockage. It also allows more air exchange in and out of the tank, helping to keep it aerobic, which is the key to preventing holding tank odor.

 

[Alan Peace]

Hi Peggie, Thanks for the info and good advice which I will follow. Regards, Alan

 

[richk]

I followed Peggy's advice in replacing the vent system for the holding tank on my previous boat, an H35 legend and it worked out well. It was a matter of enlarging the hose and through hull to allow more air into the tank. Also had to install a seal for the hose on the tank.

 

[Alan Peace]

I followed Peggy's advice in replacing the vent system for the holding tank on my previous boat, an H35 legend and it worked out well. It was a matter of enlarging the hose and through hull to allow more air into the tank. Also had to install a seal for the hose on the tank.

Hi Richk, Thanks for your advice. Could you expand a little on 'had to install a seal for the hose on the tank'. Regards, Alan

 

[DianaOfBurlington]

Caveat about nylon through-hull fittings

Hi, Alan. Note that Peggie grabbed a photo of a typical through-hull/skin fitting for illustration purposes; but please, Alan, don't use a plain nylon one! These degrade in UV exposure, of which you will have plenty in Greece, and will eventually crack, creating a leak. An alternative would be the Marelon ones, the only plastic I would suggest, or else stainless-steel or polished bronze, depending on your aesthetic preference. Groco, Attwood, and other reputable firms make these; they are available via the Internet all over the world.

I read Peggie's copious advice and fitted my boat with a (stainless-steel) 3/4" vent opening on each side of the hull in the V-berth area, the better to facilitate airflow through the tank. Works so well that sometimes it whistles! :dance:

Also, avoid the plastic ones with chromium-plated or stainless-steel covers over nylon innards; the metal heads ultimately part ways with the plastics and I don't know what keeps them together after that!

 

[Peggie Hall HeadMistress]

Good point, Diana! I posted that photo only to show the TYPE of thru-hull. Marelon is ok, but not nylon...otherwise, stainless or better yet, bronze (NOT brass!).