Midships Water Tank Vent

[britinusa]

Last time we filled the Midships tank, Peggy was below looking at the tank and I was up top managing the water flow into the fill cap. She called out to stop filling because the tank was 'blowing up'

So today we checked it out and found the problem.

The midships tank Vent line passed up on the aft side of the bulkhead at the front of the galley and disappears into the deck area right below the stanchion up top.

But the stanchion does not have a vent (unlike the vent hole in the Port Side stanchion for the holding tank vent)

I can feel the 3 nuts holding down the stbd stanchion and the vent hose in the middle of them.

This is one of those WTH moments!

I'm not prepared to remove and replace the stanchion and wondered if it would be acceptable to run a new vent hose from the tank under the galley into the space beneath the aft berth and then up to T into the existing vent for the Aft tank (the vent is visible in the cockpit on the stbd side just aft of the wheel.)

Paul

[SPembleton]

If the existing vent tube is just for water, i would not think that it would have to be vented outside. As long as the end of the tube was sigmificantly above the water level, venting to the interior should work fine. 

Is there a gap at the end of the tube now, or is the end pressed against a structure to block the end? I would think that if you just backed the tube down a little to allow air to escape from the tube it should work fine.

[britinusa]

it's secured to something with a hose clamp.

Paul

[Craig Illman]

My C30 bow and starboard water tanks share the same vent (stanchion).

Craig

[Jon W]

The lifeline stantion has a tube on the bottom that the vent hose from the starboard water tank attaches to. The stantion should have a hole in it that makes the vent. The stantion should be attached to the deck with 4 screws/bolts and nuts not 3. On my boat a couple of them were installed without washers so the nuts were buried into the fiberglass. Might be why you only feel 3?

Connecting to the aft tank vent would work as long as you stay high. Would be a lot of extra hose, why not just figure out what is wrong with the stantion vent it is supposed to attach to?

[KWKloeber]

Paul

If you re run the vent hose it MUST remain without a kink or a dip -- i.e., run continuously uphill so any water in it flows back to the storage tank.

It begs the question - where does the vent run and why not just vent it where it's supposed to be?   

My vent stanchion developed a crack at the base and I had my stainless guy repair it... The tube to which the vent line clamps to, extends up inside the outside stanchion to just below the lower lifeline. So water vented out goes up to the top of the tube before exiting the hole near the base.

-kk

[britinusa]

Thanks guys,
The stanchion does not have the vent hole (unlike the port side stanchion that does have the vent hole)

I'm guessing that a PO replaced the stanchion with a regular instead of the vented type.

Not having a dip in the hose would be difficult - near impossible 

When we top up the tank, the galley lower draw door is open and a flashlight is placed on top of the tank, then we fill the tank keeping an eye for the water level rise.
So if I just disconnect the hose from the tank and run a new hose, with an anti siphon fitting, into the bilge. Does that sound reasonable.

Paul

[Ed Shankle]

Paul, just to add more description to the stanchion vent that many of us have, it is not the same as the holding tank vent. The vent hole on mine is on the outboard side of the stanchion, just below the support arch on the base, and is only about 1/8". Verses the holding tank vent which is on the inboard side and is about 3/8". I only mention that since it originally took me a while to find it after tracing the vent hose up to the stanchion base below decks. You note that the hose is secured with a hose clamp. That sounds like the stanchion tube extension that goes thru the deck for the vent, so just wanted to be sure you were looking in the right place for the hole. It could be clogged, however, which could be why the tank expanded when filling. Others have noted it clogging.

Regards,
Ed

[britinusa]

Good point Ed.
I did not inspect the outside of the stanchion, I was looking for the large vent hole on the inside similar to the port side holding tank vent.

If the hole is there (on the outside) it may be just a blockage issue - that I can deal with 

Probably won't get to the boat till Saturday - busy week - and then we plan on an overnight cruise locally. I'll check it out then.

Paul

[KWKloeber]

The potable water vents pee overboard, the black water vents pee inboard, which makes sense if you think about it.

kk

[Ron Hill]

Paul : I'll guess that the PO gravity filled the starboard tank by filling the aft tank (which is higher) and opened both gate valves under the galley sink. 
That way the stbd tank vent hose just needs to be high as there will be no overflow.

I frequently (usually) used that method to fill my starboard tank as the aft tank has a larger fill hole! - making it easier to fill!!

A thought

[mark_53]

Last time we filled the Midships tank, Peggy was below looking at the tank and I was up top managing the water flow into the fill cap. She called out to stop filling because the tank was 'blowing up'

I noticed my starboard water tank seems bulge too.  I did not think it could be caused by water pressure during a refill since any air inside would be forced out the fill tube.  I could see how the stanchion vent would be useful when the tank is being drained since the fill cap is closed and air would need to enter as the water is used.

[Ron Hill]

All : The bulge out of the starboard tank is an old phenomena that has been discussed many times. 
I believe that it appears in all C34s with a starboard water tank. 

A thought

[Jon W]

Attached a picture of the starboard water tank vent in the lower part of the stanchion on the outboard side.

[britinusa]

Thanks Jon,
If the hole is there, then I'll disconnect the hose from inside the cabin and clean out the stanchion.

Sure hope it's that easy!

Paul