Tank odor when sailing

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Chuck

Peggy I have a Catalina 36. The stantion with the holding tank vent cracked at the vent (before I bought the boat). I installed a through-hull just below the stantion and attached the existing vent hose to the new fitting. Since then (coincidence?) I have noticed that while sailing, the cabin takes on a holding tank odor which disappears once back at the dock. There is no discharge to the bilge. The tank is only 1/4 full and we usually use fresh water to flush. Did moving the vent thru-hull create this problem? Thanks Chuck "Calm Cruiser"
 
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Peggie Hall/Head Mistress

Moving the vent thru-hull didn't cause it

Two possibilities: Sailing, tacking sloshes the waste around in the tank, forcing air/gasses out anything they can get out of--the vent and any cracks in the tank. Once the boat settles down, the odors only go out the vent. Since nothing bonds permanently to polyethylene, the only cure for the crack is a new tank. A dirty wet bilge is a "primordial soup" that can smell just like a sewer. Sailing/tacking sloshes that soup around...and just like in a holding tank, the odors get out anywhere they can. Once the boat settles down, the odors diminish. If you have a wet bilge that hasn't been cleaned in a while (just pouring some bilge cleaner and/or bleach into it doesn't count), read the article "Boat Odor Isn't All In Your Head" in the HM forum reference library and clean it as recommended.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Ask around, they all stink!

Chuck: Check around. I think that all the Catalina stink. That vent system (in the stachion) is totally inadequate. After following Peggy advise, I'd also change the vent hose and check out the rest of the hoses (there are instructions in the Head Mistress). Flush your tank with fresh water a couple of times. Then start using good chemicals. Each time you pump out, be sure to back flush you vent hose.
 
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Tom Ehmke

Tank odor while underway

Chuck, I rebuilt the waste and vent system on my ODay 272 before last season using Peggy's recommendations. I oversized the vent lines and ran two of them (my choice, not her recommendation), both exiting at a thruhull on either side of the bow well above the waterline. The odor is gone from inside the boat, and I assume that is because of the new lines and the care with which I assembled the new system. HOWEVER, when I'm sailing upwind, the stink is quite noticeable as it wafts back through the cockpit. After considering why this is happening, I concluded that it must have something to do with cross-ventilation. The plentiful air supply is entering one vent, being drawn down into the tank and then, as a result of the partial vacuum, being drawn out the downwind vent. Does that make sense, Peggy? My first choice in solutions will be to thoroughly flush out the tank before I use K.O. to treat the tank this season. If that doesn't solve the problem, I will block one of the vents with a cap to stop the cross-ventilation. Let you know what happens. Tom
 
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Peggie Hall/Head Mistress

Your explanation makes perfect sense, Tom

And here's what's happening: even with two vents, except when you're underway and forcing air through the tank with the forward motion of the boat, the tank still isn't getting enough oxygen any other time to allow K.O. to prevent odor from forming...either your vent lines are still too vertical, have bends in 'em, or both. Since the only time the tank is getting any oxygen flow through it is when you're sailing upwind, the only thing it's doing is exhausting anaerobic gasses that are forming while the boat sits in the slip. If the tank were getting enough air all the time--which has to happen to keep the inside of the tank aerobic, there wouldn't be any odor in the tank to be pushed out. You said your first choice will be to thoroughly rinse out the tank before using K.O. this season. If you didn't do that before using K.O. the first time, and haven't been at least nomimally rinsing out the tank after every pumpout and thoroughly rinsing it after several pumpouts (as the directions printed right on the back of the bottle call for), that's also been contributing to problem. If you stored K.O., even for a few hours, in your car or dock locker where the temperature exceeded 110F--which solar heat can easily do, even on a relatively cool day if it's sunny--you might just as well have been adding water to your tank, 'cuz temps over 110F kill the bacteria in it. While capping one of the vents may make the cockpit more pleasant, it won't solve the problem...and the location of your tank may make it impossible--or at least impractical on your boat--to vent the tank sufficiciently to allow a live aerobic bacteria treatment (K.O.) to work in it. However, Odorlos might...it works on the same aerobic principle as K.O., but instead of relying on a sufficient supply of oxygen from another source it uses nitrates to promote oxygen release from the waste itself. Odolos often works in tanks that K.O. can't. However, you'd still have to rinse your tank out regularly, or it won't work either...nothing will.
 
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Tom

Steve. I have a Catalina and it's Holding tank

Doesn't emit odors. MAybe its a different design I have a newer (1999 C36). Yes, all I have is the vent stantion and it seems to work fine. Maybe its because all the C36 carries for a holding tank is 17 gallons or maybe its the way the tank vent is routed. The only time I get any odor is when I overfill the holding tank (oops !!). I have mitigated that problem by installing the accugage...(works great). There are a *few* things I do that might help the situation though 1) I use K.O. (I might try Odorloss just to try it though). 2) I try and rinse the holding tank after I empty it --- sometimes I just fill it through the tank vent just to make sure thats clear. 3) I disconnected my intake water from the thru-hull to a "T" in the sink drain. This way when I leave for the boat for more than I few days, then all I do is close the thru-hull put some fresh water down the sink with a squirt of CP and pump that through the head. Now when I come back after a week or whatever I don't have that terrible rotten egg smell I used to get.... One question for Peggy.... I have not been so religious with the white vinegar. Do you think a 2-3 year old boat is affected that much? Do you think the damage (urine/salt water crystals) are that bad by now? What can I do to ensure that the lines are "squeeky clean" again? Is there a one time procedure that I can do? (an then I will do the maintence cup of vinegar when I close the boat up)
 
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Peggie Hall/Head Mistress

Only one way to find out...

Disconnect the head discharge hose from the toilet and look at the inside of it. If it's becoming blocked by sea water minerals--and btw, those minerals don't do any damage to the hose, they just build up and clog it--you'll see it. If the hose looks open, you're ok. If there is a major buildup, several applications of undiluted white vinegar several days apart will dissolve 'em (or you can do it in "one shot" with a 12% solution of muriatic acid...but be VERY careful with that stuff!)...then prevent it from happening in the future with regular doses of white vinegar. Putting it through the sink will also make sure it gets through the intake hose too.
 
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Laura Bertran

Steve Dion

What holding tank chemical do you use in your H31? I want to try Odorlos but I'm afraid the H31 tank isn't well vented enough. Thanks. Laura Bertran 1985 H31 #514 Rising Tide
 
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Tim Schaaf

Comment for Laura

Odorloss claims that it is actually meant for poorly vented tanks, and it works fine in my Hunter 33, which has a very small vent, indeed.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Couple of different ones.

Laura: I have used odorlos and it seems to work fine. You can use almost anything when you have good hoses. Nothing works when they are bad!
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Tom, Bad choice of words.

Tom: I knew when I posted this that ALL was not a good choice of words. There have been several posts about this subject (Catalina specific) and they seem to have a common problem with this. One of our friends with a Cat'34 has the worst problem. This vent line cannot be easily flushed. I think if you can keep the vent line clean the system will work fine.
 
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Tom

The way I keep the vent line clear on my C36

(which has the stantion vent) is just to run a hose over to it with a high pressure nozzle and just stick it in the vent hole. If it's just a little blocked then I beleive the pressure from doing this helps keep everything clear. If it truly blocked then I guess you will get the spray back out of the stantion vent. ........plus if it was then I could beleive that the boat will start to have holding tank odors fairly quickly.......one must keep that vent clear or there will be *lots* of problems....
 
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Peggie Hall/Head Mistress

Steve, how can hoses affect odor out a tank vent?

Hoses are inside the boat...the tank vents to the outside of the boat. Yes, hoses can create odor INSIDE the boat--because the odor is coming from the hoses themselves. But odor out the vent comes from inside the tank, not from the hoses. The article "Head Related Odors--Causes and Cure" in the HM forum reference library explains in detail why odor inside the boat and odor out the vent line are two entirely separate issues...why it's quite possible to have odor out the vent, but none inside the boat (which misleads many people into believing they have no holding tank odor)...or a boat that reeks inside, but no odor out the vent...or both. Replacing hoses cannot cure odor out the tank vent...no tank treatment can cure odor inside the boat...any more than taking a bath can cure bad breath or mouthwash can cure body odor. They're two separate issues that require separate cures.
 
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