Water Tank Vent & New Holding Tank Vent FLIX

[Lance Jones]

In reading all the old postings on the water tank vent, I happened across an article in Sailing World about "Basic Fresh Water Storage." One idea they put forward is to run the vent to the sink. Has anyone tried that? I want to get rid of the vent through the stanchions for both waste AND water. This seemed like a good solution to the water. I have the solution for the waste already.

[Roc]

Lance, why would you want to run your waste vent to the sink?  Here is the waste vent that I installed, per Peggie's suggestions.

[Stu Jackson]

Lance, IIRC we had a discussion recently about simply joining the starboard water tank vent to the aft tank vent for the water.  Then, of course, the starboard vent stanchion would have to be plugged or the stanchion replaced with a non-vented stanchion.  From a purely plumbing point of view, I'm not sure how the vent to the sink would work, since vents need fresh air to allow the pressure to equalize.

The vent "correction" for the holding tank has been described many times:  standard thru hull high up under the gunwale.

[Peggie Hall]

Roc, it's his WATER tank he wants to vent to the sink, not his waste tank.  However, sink drains are kinda skanky...and when the water pump runs it pulls air into the tank via the vent to replace water as it's pulled out. I wouldn't want my fresh water system to breathe the air in a sink drain. Some people vent their water tanks in the bilge...I wouldn't want my fresh water tank to breathe the air in most bilges either!

It's only waste tank vents that don't belong in the stanchion...there's no real reason why the the water and fuel tanks can't stay there.  The holes in the stanchion enough air for fuel and water, and their location on the aft side of the post keeps sea water out when the rails are in the water.  So I'd move the waste tank vent to a thru-hull and leave the fuel and water tank vents alone.

[Lance Jones]

Yes, it's only the WATER vent I want into the sink. Peggie, thanks, I didn't think of the vent air going in AND out. You're right. I'll probably leave where it is and just re-bed with the Butel (SP) tape. People seem to want to grab that specific stanchion to pull when they help with docking etc. I even have Ron's (I think) suggestion of a designated pull-this-rope-instead-of-the-stanchion rope. So the constant back and forth tension on that stanchion breaks the seal.

[Bobg]

Hi Roc, just wondering, wouldn't you want a clam shell cover on that?  I mean, won't water come in when heeling?  getting ready to do something like that myself, although on my 88 I'll have to route the OEM small hose out under the gunwale as I can't get a bigger elbow for a bigger vent hose under the seat that will fit like you did,

[Roc]

Bob,
Peggie does not suggest adding a clamshell cover.  The object is to move as much air into the tank.  I mounted it right behind the v-berth cabinet on the port side, so it's not at the beamiest part of the boat (for heeling reasons).  It's also mounted as high as possible as the picture shows.  Here are more pictures from the inside, showing how the hose is routed.

[Peggie Hall]

Bob, Peggie does not suggest adding a clamshell cover.  The object is to move as much air into the tank. 

Actually I DO recommend a clamshell cover over ANY vent thru-hull that will more than a few seconds at a time under water when the boat is heeled. 

However, if we're still talking about the water tank, the vent only has to allow enough air flow to provide an escape for air displaced by incoming water when the tank is filled and provide a source of enough air to prevent the water pump from pulling vacuum when you open a faucet...we're not trying to keep the tank aerobic. But we do need to keep sea water out of the potable water supply. So not only do you want a clamshell over ANY thru-hull that could take on sea water, but--unlike a waste tank vent line, a high arch in it is also recommended...so that any water that might get into the vent line just runs back out again instead of going into the tank.  And the same is true of a fuel tank vent line...clamshell where advisable and high arch.

[Roc]

Peggie,
If you look at the picture in my earlier post, that is the thru hull fitting I used, straight out with no clamshell cover, based on the discussion we had when I did my holding tank vent modification.  As you can see, it's a couple of inches below the rub rail.  If I'm sailing with the boat heeled over that much, time and time again, I wouldn't be doing a good job at trimming the sails, and keeping my crew comfortable.  Also, that much heel is not very efficient anyway.  I would have to be heeled over pretty far for that thru hull to be underwater.  I've had this set up for 10 years now with no issues....and happy to say a very sweet smelling boat!!  I appreciate your advice.

Thanks!