Holding Tank Vent

If you stick a short piece of dowel in the ends of both the old hose and the new, you should be able to pull the new through when the old is pulled out. This will eliminate the routing issue. If the dowel is large enough to be really tight, you can eliminate the

need for a clamp and avoid its hanging up on corners and edges.

--- Bill Culbertson <billculb_a2@yahoo.com> wrote:

Chris,

I replaced the vent host this summer. It's quite easy and I wish I'd done it years ago. I finally decided that my head smell must be the vent hose from back when, as a 1st year newbie, I overfilled the tank and you guessed it - YUCK. Spent about $20 for 10' of hose and it turns out it took about 6'. I can't swear about the 6' so if I were you, I'd buy 7' to be sure.

Don't take off the mirror. That is complicated by the 2 anti-siphon hoses that would have to be removed. Instead access from the hanging locker in the aft cabin. In the hanging locker, take off the thin wood panel which supplies the "back wall" of the hanging locker

(between the hanging locker and the head). This is screwed in with four screws to wood blocks glued to the hull (outboard) and head wall (inboard). Once removed, you'll see the whole arrangement very clearly. Now go to the head and remove the screws holding the medicine cabinet to the wall. I know, I know - I said don't remove this cabinet and you

> don't. But once unscrewed from the head wall, you can pull it forward toward the head door (toward the boat centerline). You pull it forward 2-4" - whatever it will do WITHOUT detaching the anti-siphon hoses.

Now back to the hanging locker. With the wall removed and the medicine cabinet pulled inboard, there is quite a bit of room to access the head vent hose as it attached to the fitting on the hull. Undo the hose clamps and detach it from the fitting. Detaching the other end at the holding tank is easy as it is on the top of the tank easily accessible from the starboard settee with cushions gone. Once detached from the holding tank, take note of exactly how it leaves the tanks and heads outboard relative to the various obstructions on top of the tank. That's the only thing that you'll wish you'd noted before you pulled the old hose out. Then just pull the hose out.

For the new hose, I fed it in from the holding tank following the path I noted that the old hose took. Push it horizontally until you've fed 4' or so. Then return to the hanging locker with a flashlight or headlamp (what I use). You can reach in and grab the free end. Pull it upwards following the path the old hose took. I remember there was a loose cable tie that it went through around it along with one or more other hoses. I think one was the large diameter pumpout hose on its way up to the deck fitting. I DIDN'T cut that cable tie to remove the old vent hose. I just pushed the old hose down out of it. So I fed the new hose up through the original cable tie and toward the hull fitting.

I hose clamped to the hull fitting 1st. I used dish soap to make it easy to put on and then attached the hose clamp. Then I went back to the settee and the holding tank. I fiddled with the hose back and forth horizontally to find out the max. hose length I could keep and still have it cleanly reach (and not overshoot) the holding tank fitting. Then I cut the hose to that length, soaped it up, attached the hose clamp and it was a done deal.

Like I said, I really wished I had done it a few years ago. I have had absolutely NO odor since.

I finally got to suspecting the vent hose when I noticed that the odor I did smell when it happened was strongest in the aft cabin and particularly in the hanging locker when I opened the door to the locker. That's how I figured out that this locker was an open path to the vent hose in the first place.

I hope this process works as well for you as it did for me.

-bill

Harmony #859

I would like to remove and replace my head vent and possibly vent hose. Does anyone have a good written process? How does one get to the fitting? remove the mirror or other bathroom wall parts? where does the other end of the vent hose terminate? the holding tank? any gotcha's to look out for? thanks,

Chris

Amore #139

I asked this question a few months ago, but am still having a problem. Bought a 2001 Cat 320 last fall and noticed a fairly strong head odor. The first thing I'm trying to do is verify my holding tank vent hose is not clogged. I can trace the hose off the tank to the starboard side then it disappears up the wall and I can't see how to get access to it. I believe it attaches to the stantion for venting. Has anybody ever changed this hose? How did you get to access it where it connects to the stantion? I took the mirror off in the head thinking that would allow me back there, but no luck. My battery switch is on the starboard side on a panel. Has anybody ever taken that off ? Was the vent hose back there? Thanks in advance

Gary #845

Your hull is close in age to mine (#859) so likely our boats are the same layout.
On my C320, the head vent emerges from the hull's topsides - not the stanchion.  There
is a fitting on the topsides just below the rubrail not far aft of the pumpout deck plate.  Thereis a metal fitting identical to the fittings on the stbd side of the transom for water and diesel tankvents.

If you are extremely careful, you can just unscrew that fitting from the tank vent.  Very likely it is the fitting itself which is clogged as mine gets clogged 2 times a season from insects.  Just take the fitting off and clean it and put it back on.  Now the reason that I say 'very carefully', is that once you unscrew the metal fitting, there is nothing except friction to keep the male vent hose threads from disappearing into the hull.  I understand from this list that this is VERY inaccessible if that happens.  I think that's part of what you've iscovered yourself in trying to trace the hose though the medicine cabinet etc.

What I ended up doing was buying a little grey plastic fitting at my marina's chandlery with female threads the same size.  It can be anything - as long as it has the right thread size.  Once I carefully remove the metal head vent fitting, I immediately screw this grey plastic fitting onto the exposed male hose threads to keep the hose from disappearing into the hull.  Then I take my time cleaning out the metal fitting.

While you are in this configuration, another good thing to do is to be sure that the hose itself isn't blocked.  Mine was the 1st time I did this b/c I overfilled the holding tank and "stuff" went up the vent hose.  Once that happens, it won't drain itself and you won't have a vent.  That will quickly lead to odor.  So what I did/do is when I have the metal fitting
off and the plastic fitting in place, I unscrew the deck plate and blow into the grey plastic head vent temporary fitting. If you get resistance, the vent is not venting.  You then blow with enough pressure to blow the 'stuff' back into the tank and open the vent hose ompletely.  You take the deck plate off so that there's a place for this air to go otherwise, of course, you are trying to blow up the holding tank like a balloon since it's a closed ystem.

Turns out that the actual grey plastic fitting I bought has threads that match the head vent on one end (as described) and has garden hose threads on the other end.  So I can attach a garden hose to the other end of that grey fitting while in place, to flush out the head vent hose of "stuff".  I think I did that the one time I had 'stuff' in the vent.  Now with a clean vent hose but full of water, I did the above procedure to blow the water all the way into he tank and leave a freely venting vent hose.

Once the vent hose is clean and clear and the metal fitting cleaned out, then just swap the grey plastic fitting for the original fitting and all is now well once again.

When my vent got clogged, I experienced an odor problem.  Since I've done the above to clear it out, there has been no more odor problem.  As I mentioned, I clean the metal itting once or twice a season to keep it that way.  Insects seem to love this thing.

Good luck,
  -bill
"Harmony" #859 Ann Arbor, MI (sail Lake Erie)

My boat #809 doesn't use the stanchion for the vent.  It vents out a vent on the side of the boat.  The dealersaid I should make sure that the screen in this vent is removed to keep it from clogging.  I must have the "experimental" model, because I also have the side mounted fuel tank vent. :)

This is what solved our head odor problem mostly.
1) we leave the head hatch cracked in the "vent" setting and leave the head door open whenever we leave the boat.
2) we leave a 1-gallon milk jug in the sink and only flush with fresh water, and use alot of water so that you don't leave "anything" sitting in the hoses.  Fresh water flush makes a huge difference over sea water.
3) when pumping out, use lots of fresh (preferably hot/warm) water to flush out the tank.
4) Use some good quality scented lysol-like cleaner and wash off the hoses behind the head fairly often.

Check to be sure that the vent loop in the medicine cabinet is clear and working well.  Ours was installed so that it was jammed right up under the shelf and was pretty much plugged.

I think one of the best things to do (project for next year) is to replace the stock hoses with some high quality ones.  Others on this list have done this.  Don't know what their results were.