Water Tank Breather

Lance Jones · March 14, 2011, 07:54:48 AM

Along the lines of the holding tank breather, would the same concept with a 1" mushroom vent work here as well? I'm really tired of a vented stanchion.....

Ken Juul · March 14, 2011, 08:12:58 AM

Yes. But for us salt water sailors there is the risk of contaminating the tank with sea water if the rail is buried.

Peggie Hall · March 14, 2011, 09:45:47 AM

Quote from: Ken Juul on March 14, 2011, 08:12:58 AM
Yes. But for us salt water sailors there is the risk of contaminating the tank with sea water if the rail is buried.

Not if you put a clamshell cover on it...Which, btw, you also need on the waste tank vent thru-hull.

Ken Juul · March 14, 2011, 11:30:16 AM

I'm drawing a blank.....how is a clamshell cover going to stop water intake?

Stu Jackson · March 14, 2011, 01:33:05 PM

Lance, there IS a BIG difference. If you look at the vent for your aft water tank, right under the starboard coaming by your right leg when standing behind the wheel, you'll see the vent for that tank. It is a "traditional" vent fitting, small round silver thing, which has a screen in it, too. This is an appropriate vent for a water tank, but NOT for a holding tank. Peggie has noted the differences and the reasons why, in her posts here on this board. The water tank vent serves only two purposes: letting air out when you fill and in when you use the tank. Because the water tanks don't need the larger amount of air required for the chemical reactions in holding tanks, these vents can be much smaller.

Ken's right, you don't want to mess with the chance of getting non-potable water into your water tanks. The length of the vent is not important for water tanks. If you want to get rid of the vented starboard stanchion, then run as long a vent line as you want to a location somewhere like the one for the aft tank, and buy the same vent fitting for it, or you could tap right into the aft tank vent behind the coaming.

We fill our starboard (smaller) tank via the aft tank anyway. That's 'cuz the fill hole for the aft tank is much bigger than the starboard fill hole. Open both tank valves under the sink, fill via the aft tank fill hole, close whichever tank valve you don't want to use, and you're done.

Another thought is that the vented stanchions aren't the problem. It's the fact that the two vented stanchions are definitely the ones most visitors grab and pull on all the time that creates this recurring issue. So bedding them properly, and getting folks to stop pulling on them is another answer. If other people understood just what a bear it is to rebed a stanchion 'cuz of the work involved in getting to the nuts on the bolts down below (like, if you made THEM do the work) you'd rarely have a problem, even with vented stanchions.

Don't need to use a mushroom vent for a water tank.

Ron Hill · March 14, 2011, 03:10:59 PM

Lance : The problem is -- where to put the mushroom vent for the starboard tank, as the vent must be on the outside. Just in-case your brother-in-law pressure fills the starboard tank (helping you) and the overflow water squirts out the vent it's got a place to go on the outside - well above the water line.

I wouldn't screw around with the present stanchion vent for the starboard water tank !! A thought

Peggie Hall · March 15, 2011, 01:46:08 PM

Quote from: Ken Juul on March 14, 2011, 11:30:16 AM
I'm drawing a blank.....how is a clamshell cover going to stop water intake?

About the only way you're gonna take on water via a vent thru-hull is when the thru-hull is below waterline due to heeling and the pressure of the water against the hull forces water up the vent line But water will just flow over a clamshell that's open end at the AFT end...it can't get into the thru-hull. That same reason--avoiding the "ram water" effect--is why the vent line openings in the stanchions are on the aft side of the stanchion...you'd have to be backing up with your rails in the water to take on water through it.

It's also advisable to put as high an arch as possible just before the thru-hull in a fuel or water tank vent line (but NOT a waste tank vent line!) so that any sea water that does somehow manage to get into the vent line will only run back out again instead of continuing on to the tank.

Lance Jones · March 15, 2011, 02:06:24 PM

Good insight all.

Ken Juul · March 15, 2011, 02:10:20 PM

Thanks Peggie. That makes perfect sense. My vertically oriented mind didn't consider putting it on sideways

The only thing I would be worried about is ripping the clamshell off on a less than perfect landing....port side to is my preferred docking side. I guess if held on by caulk and not screws it would be lost but minimum damage.

scotty · March 15, 2011, 07:16:28 PM

A little story for you'all.... when I was younger I was on a purse-sein tuna boat. We left on one voyage and someone forgot to seal the cap for the fresh water tank. Salt water got into the tank. We were out to sea for 5 months. In all that time the only fresh water on board was made from condensation in the reefer alley (cooling the fish holds) made by the chief engineer. Only engine crew, of which I was one, had access to true fresh water. All the rest of the water was potable, but slightly "briney". We made landfall in Acapulco. The fresh water there was great, but that's another story.....