Is vent clogged again?

[Pat]

Our head vent (O'Day 272 LE) appears to be clogged again.....I need to go to the pump-out
station this afternoon, and am pre-judging that I must clear the vent hose before trying the pump
out.....Do you agree?.....it's not hard to take off the vent fitting because, in my mind I'm thinking the sewage cannot be pumped out if the vent is non-working...do you concur.....Patrick

 

[Peggie Hall HeadMistress]

You guessed right...you won't be able to pump out if the vent is blocked. The pumpout will pull a vacuum that won't let it remove more than a gallon or two--which can mislead you into thinking it got the whole tankful. Worse yet, a particularly strong pumpout can even implode a tank.

Before you remove the vent fitting, open the deck pumpout cap to relieve any pressure in the system (Might be a good idea to have a hose at the ready and be sure to be UPwind from the fitting). However, the vent thru-hull fitting may not be the only thing that's blocked. Heeling can cause waste to spill into the vent line, which can result in a clog at the vent fitting on the tank--both the fittting and that end of the vent line. So you need to check both.

There's a easy way to prevent vent blockages: replace the vent thru-hull with an open "mushroom" or "bulkhead" thru-hull that you can stick a hose nozzle up against and back flush the vent line every time you wash the boat and/or pump out...and then DO IT every time!

 

[Beverly55]

Why can't we use the traditional methods like pouring hot water, baking soda + vinegar mixture to unclog? Does it work?

 

[Apex]

Why can't we use the traditional methods like pouring hot water, baking soda + vinegar mixture to unclog? Does it work?

if you have a clogged system, putting in a mixture that creates expansive gases, that could create quite an explosion........?

 

[Peggie Hall HeadMistress]

Why can't we use the traditional methods like pouring hot water, baking soda + vinegar mixture to unclog? Does it work?

Clearing a vent line isn't clearing a clog in a hose...the blockage is almost always at both ends of the vent line--in the vent thru-hull and at the other end of it--in the end of the hose and in the tank fitting. So I dunno how you'd use vinegar and baking soda to clear it. You would want to pour it down the toilet...you already have a pressurized tank. The pressure could burst the tank or cause it to erupt through the toilet. There's only one way to clear a blocked tank vent: scrape out both ends of it as I described above.

But you'd need to be very careful using vinegar and baking soda in drains on boats too because they're almost always 3/4" or 1" hoses, not 2" hard pipe used in houses. A mixture that would be ok at home can be waaay too strong to use in a drain on your boat...it could blow out a fitting or even burst a hose. You don't want to use commercial drain openers on a boat either...the chemicals in 'em can damage hoses and pumps. Judicious use of a plunger can be ok in a sink, but never use a plunger in a marine toilet because it'll damage the pump (household toilets don't have pumps). Household chemical bowl cleaners will damage hoses and rubber parts in toilets...so will bleach, Lysol, pine oil cleaners and most household cleaning products. Using the wrong products can do more harm than good, often turning one problem into several...often so gradually over time that you don't realize that using it is the culprit.

As with most things, prevention is always cheaper and easier than cure and my book (see link in my signature) explains how to prevent problems in your boat's plumbing and sanitation systems so you'll rarely if ever have the need to cure 'em..

 

[DayDreamer41]

Not to highjack this thread but I though this would be a good place to ask, the pictured is the through hull vent that I have, I suspect given the odors we are experiencing that the vent is some how plugged, I have attempted to push water from a garden hose through this from the outside and it appeared that no water was penetrating the vent. In looking at this from the inside the boat it appears like a difficult task to even get to the hose connection at the vent fitting. Would putting a shop vacuum on this fitting possibly clear any obstruction? is there going to be more effort required? It doesn't appear that the center of the vent is removable and I would imagine that the vent only allow (1)-way floe so as to prevent inbound flooding.

 

[Peggie Hall HeadMistress]

Replace the thru-hull with one of these

any material except nylon

 

[DayDreamer41]

Peggie,
I feared that you would recommend this change but what is the particular reason as to why one would need to change to that style vent?
Are there any precautions required to prevent down flooding other than ensuring it is higher than the steepest lean angle?

 

[Justin_NSA]

Your vent line should already have an upward loop to prevent water from getting though.

 

[Peggie Hall HeadMistress]

It's completely open, allowing the exchange air needed to create an aerobic environment in the tank--that is, provided the vent line is short and relatively straight--and also allows you to prevent vent blockages by making it possible to stick a hose nozzle up against it to back flush the line.

Are there any precautions required to prevent down flooding other than ensuring it is higher than the steepest lean angle?

Your vent line should already have an upward loop to prevent water from getting though.

Only if you want odor out the vent...

So-called "vent" thru-hulls are designed to keep sea water out of fuel and fresh water tanks...very important for fuel and water, but hardly necessary for sewage tanks. Water splashing against the thru-hull won't put enough water into it to notice...but you don't want to heel enough to "submarine" any vent thru-hull for very long. I advise people who plan to do any serious blue water cruising that could put 'em into conditions that keep their decks awash for days or even hours to put a shut-off valve on the holding tank vent line. They'll be flushing directly overboard at sea, so it won't matter if the vent is closed...and they can open the vent again when conditions improve.

 

[Ron20324]

If you have the mushroom type thruhull, you can stick a hose against it (if you have a large TH, you can stick a hose INTO it. With the deck plate off, you should be able to see the level come up the pipe and know the vent is clear. Go with the mushroom and a larger vent hose, and know that's one less potential problem.

 

[Justin_NSA]

That's on my next off-season to-do list

 

[DayDreamer41]

Thanks for all the insight, I guess I know what I will be doing soon, sooner that later, the odor is rather pungent, but only when we flush. Looking at the owners manual waste schematic it appears that a valve is already installed, this is a good thing. I thought I read somewhere that it was ill advised to have a loop in the waste tank vent line, not sure where I read that as I have been doing a ton of research on the subject.

 

[Peggie Hall HeadMistress]

Looking at the owners manual waste schematic it appears that a valve is already installed, this is a good thing.

If you mean a shutoff valve in the vent line, I can just about guarantee no builder has ever installed one. I have owners manuals for every toilet...which version of the Jabsco manual toilet do you have? What's the part number that you think may be the valve?

 

[DayDreamer41]

Peggie, the information gleaned was from Hunter's owners manual demonstrating the piping layout and locations of through hull fittings, tanks and pumps of the waste systems.