waste tank

[tomsboat]

I have a 40 ft 2007 mainship trawler.Sometimes when I flush the bowl I get a odor.The tank is 1/4 full and it is fresh water system I put in a deodorizer .Is there a filter at the air vent.If so how to you get the air vent off.Its on the starboard side.Tom

 

[O C Diver]

More air flow through the vent line makes a big difference with odors. Make sure yours is clear first. I spray fresh water into the vent after every pump out to make sure the line is clear.

Ted

 

[Gmarr]

Where is the odor coming from? Smell like rotten eggs and from the toilet bowl? Or is it elsewhere?

 

[tomsboat]

odor

the odor seems to be outside the boat but also in the salon

 

[HeadMistress]

The odor outside the boat is from the waste holding tank, forced out the vent when you flush. Obviously the "deodorizer" you're using isn't working..but it may not be entirely the product's fault.


However, it's unlikely the tank is the source of your odor in your salon unless it's coming in through an open window on the same side as the tank vent thru-hull. Otherwise the most likely source is permeated sanitation hoses.


You asked if there's a filter in the vent line. The first thing you need to do is trace the vent line from the top of the tank all the way to to the VENT thru-hull to find out. If there is, get rid of it..filters actually help to create the very problem they're sold to solve (if only I could have invented something that does that!) If there is no filter, a long convoluted vent line makes the air exchange the tank needs to prevent odor impossible.

I could go on typing here for volumes but ALL of this--what causes odors and how to cure, better yet, prevent 'em--is explained in detail in my books (see link in my signature...just click on the title). There are always issues to specific to any system that can't be covered in any book, and I'm always glad to help you deal with those.

--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[Comodave]

Peggie is correct, get rid of any filter and get more air into the tank if your problem is smell coming out of the vent when you flush the head. If you can’t get more air in by a good vent system tey something like Groco’s Sweetank system. It works great.

 

[Bacchus]

I am not aware that MS installed filters. I am still trying to find a way to install a new larger vent and think I have it by going fwd under bed to bow by anchor locker.
I have solved the odor problem on my MS 34HT w a DIY bubbling system.
For info see Bacchus link and scroll thru Projects.
Happy to answer any questions.

 

[Jgutten]

Don, Mainship did install filters and, as Peggy said, get rid of it.

We installed a vent line just as you described. One inch, under the bed, few bends, next to the anchor drain. Works great! You're on the right track.

 

[Bacchus]

Jeff
Thanks for clarifying.
Mine never had one but the vent is poor. My bubbler works but Peggie madw me a believer on previous boat.
It may have been a post of yours thatgot me looking.
Hose is in place and I have been waiting for haul out to instalk the thru hull.
Thnx again

 

[Dougcole]

I just finished installing a new 1 1/8" vent on our 400. I was inspired by Jeffery, Peggie and Don. Same deal, I was getting a puff of very foul air from the vent with every flush.


Here is a detailed description of what I did, the vent is accessed through the plate in the floor just aft of the master bed.



1. Cut the old 3/8 inch vent line and cap off. Would be better to remove it, but that would be a pain to access. Using a pipe wrench to unscrew the old vent fitting from the tank.


2. Replace with a threaded/barbed fitting. The closest I could find was a 1 1/4" fitting, but I couldn't find a 1 1/4" through hull, so I necked it down to 1 1/8 using an adapter. Attach the hose, you need about 13 feet. I used sanitation hose.


3. Slide the hose Fwd under the floor under the bed. Slide the mattress back and open the plate underneath it. Climb in and scope out the area under the FWD bulkhead. You can see where the anchor locker drain and the drain for the Fwd AC come out under there.


4. Hardest part. From outside the hull, drill a hole through the hull just aft of the anchor locker drain. I did it from my tender. Install an open through hull there, not a holding tank vent. My hull was cored there, so I coated it with epoxy and then sealed it with 4200. Climb back in to the hole under the bed and attach the fwd end of the hose using appropriate hose clamps.


Easy Peasy. I hope it works.

 

[Bacchus]

Doug
Good job done
I think you will find an immediate improvement.
I started using NoFlex treatment about the same time I added my bubbler based on recommendations here on TF. I have been very satusfied and recommend it. I think it has cleaned up the tank as the flush after pumping out seems to be cleaner.
I recently picked up an endoscope for phone or tablet connection and willget a chance to inspect the tank when I rrplace my vent... provided I remember to take the scope w me!!

 

[Cigatoo]

“Replace with a threaded/barbed fitting. The closest I could find was a 1 1/4" fitting, but I couldn't find a 1 1/4" through hull, so I necked it down to 1 1/8 using an adapter. Attach the hose, you need about 13 feet. I used sanitation hose.”

Sorry for thread drift. Is this a plastic tank in your boat? I would like to add an additional vent but not sure if a threaded barb will thread into a plastic tank. Don’t want to have to go inside of the tank for obvious reasons. (My boat is not a Mainship. )

 

[Bacchus]

“Replace with a threaded/barbed fitting. The closest I could find was a 1 1/4" fitting, but I couldn't find a 1 1/4" through hull, so I necked it down to 1 1/8 using an adapter. Attach the hose, you need about 13 feet. I used sanitation hose.”

Sorry for thread drift. Is this a plastic tank in your boat? I would like to add an additional vent but not sure if a threaded barb will thread into a plastic tank. Don’t want to have to go inside of the tank for obvious reasons. (My boat is not a Mainship. )

Threaded ftg will work if there us an existing ftg and you csn increase hose size w a larger barb.
Sone tanks might have a pkugged fitting that can be removed and a barb inserted.
Tank walls are not thivk enough to drill & tap but there are fittings that do not require ibside access. I forget the brand name but would suggest a little Google searching or PM Peggie... aka Headmistress and I'm sure she can provide the retrofit fitting info.

 

[Sea Q]

I have a 40 ft 2007 mainship trawler.Sometimes when I flush the bowl I get a odor.The tank is 1/4 full and it is fresh water system I put in a deodorizer .Is there a filter at the air vent.If so how to you get the air vent off.Its on the starboard side.Tom

You are going to have to track the vent line from the tank .If there is a filter it will be higher that the tank and probably is a space that is semi easy to work in .
If there is no filter and you are getting smells there are treatments that will fix the problem smells and cheaper and easier than redoing the vent line

 

[HeadMistress]

I would like to add an additional vent but not sure if a threaded barb will thread into a plastic tank. Don’t want to have to go inside of the tank for obvious reasons.

You won't have to. Adding a new vent fitting in a plastic tank is actually pretty easy, thanks to a li'l gizmo called the Uniseal UNISEAL It's very inexpensive and will NOT leak. It's used in a lot of applications...in fact, Dometic/SeaLand uses 'em for their "diptube retrofit kit." You can use a short piece of sch 40 or sch 80 pipe or plastic plumbing fittings available from any decent hardware store for the hose fitting ...it just needs to have an OUTER diameter that's the same size as the hose INNER diameter.

It's a good idea to talk with the folks at Aussie Globe when you order it to make sure you cut the right size hole (use a hole saw to get a perfectly round hole) and get the right size Uniseal for the hose size.


A threaded plug (also available from any decent hardware store) wrapped in plenty of teflon tape will seal the existing vent fitting on the tank.


--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[Cigatoo]

I would like to add an additional vent but not sure if a threaded barb will thread into a plastic tank. Don’t want to have to go inside of the tank for obvious reasons.

You won't have to. Adding a new vent fitting in a plastic tank is actually pretty easy, thanks to a li'l gizmo called the Uniseal UNISEAL It's very inexpensive and will NOT leak. It's used in a lot of applications...in fact, Dometic/SeaLand uses 'em for their "diptube retrofit kit." You can use a short piece of sch 40 or sch 80 pipe or plastic plumbing fittings available from any decent hardware store for the hose fitting ...it just needs to have an OUTER diameter that's the same size as the hose INNER diameter.

It's a good idea to talk with the folks at Aussie Globe when you order it to make sure you cut the right size hole (use a hole saw to get a perfectly round hole) and get the right size Uniseal for the hose size.


A threaded plug (also available from any decent hardware store) wrapped in plenty of teflon tape will seal the existing vent fitting on the

Thank you Peggie!

 

[Dougcole]

I've been on the boat for four days since we finished upsizing and relocating the vent. No more odor! I've used Noflex in the past, and would use it again, but Hopkins Carter was out of it the last time I was in, so I've been using KO instead. Honestly, neither of them worked for very long before the bigger vent, but I bet they both work now.


As far as the fittings go, I probably could have looked harder and found a 1 1/4" thru hull, but I needed to get the job done and west marine had the parts to do it in the 1 1/8, so that's what I did. FWIW, I don't see much point in going with a hose and through hull any bigger than the threaded opening in your tank. The size of the opening will constrict the air flow, even if it is attached to bigger hose, correct?


Either way, 1 1/8 seems plenty big for a vent hose. Way more airflow than the 5/8 that was on there before.


I may use one of Peggie's cool seals and reattach the old vent as well, even though it's small, it would help a little, and it is already run.

 

[Comodave]

I would go ahead and hook up the old vent, more air can’t hurt. In a previous boat I was redoing the head system with all new everything. I put in a 1” vent from each side of the boat so air could flow through easily. Worked very well.

 

[Captain Ron D]

Does anyone out there with a Mainship 400 have any experience in cleaning the Holding Tank Float? Mine seems to indicate 1/2 or slightly more after having it pumped. I watched the 'Holding Tank Technician' when he pumped it out and his estimate matched the capacity, plus or minus a few gallons, however the gauge still indicates around 1/2 full. Any experience with this would be appreciated. The sending unit is in the top of the tank, and is under the sold of the passageway and there is insufficient clearance to remove the sender from the top of the tank without using a circle saw and creating an opening. Thanks for any advice. Captain Ron D.

 

[Jgutten]

Captain Ron,

First, on the MS400, you must cut an access hole into the floor to lift out the float sender unit. It's an easy thing to do, but it allows access to the sender unit.

When I pulled out my sender, I couldn't get it out of the tank because it was filled with crusted poop! After pulling on it, it finally came out. I decided to replace the sender unit with a new one. They're not expensive but a new one is worth it.

Second thing is to buy RV Digestit at a local RV store. Dump the entire bottle into the toilet and fill your tank up with water. Let it sit for a day or two and presto! the sender unit will work. RV Digestit is fabulous stuff. It unplugs sender units.

Here's link to their site:

https://uniquemm.com/products/rv-digest-it-holding-tank-treatment

 

[HeadMistress]

Does anyone out there with a Mainship 400 have any experience in cleaning the Holding Tank Float?

Better yet, just leave it where it sits and install a tank level monitor that uses senders that go on the outside of the tank. Profile Tank Monitors If your existing system is a Dometic/SeaLand Tankwatch, you can use the same wiring. The single Tank "Solo" is inexpensive and easy to install.


--Peggie

 

[ranger58sb]

Does anyone out there with a Mainship 400 have any experience in cleaning the Holding Tank Float? Mine seems to indicate 1/2 or slightly more after having it pumped. I watched the 'Holding Tank Technician' when he pumped it out and his estimate matched the capacity, plus or minus a few gallons, however the gauge still indicates around 1/2 full. Any experience with this would be appreciated. The sending unit is in the top of the tank, and is under the sold of the passageway and there is insufficient clearance to remove the sender from the top of the tank without using a circle saw and creating an opening. Thanks for any advice. Captain Ron D.

I see in other posts too that access is the issue.

If it's a new-ish WEMA stainess steel sender, cleaning it is trivial, once you can get it out. Just plop it in a solution or muriatic acid or whatever and let it take care of itself. Doesn't hurt to have two sensors, 'so you can replace the old one right away (5-minute job, given OK access), then clean the old one at your leisure.

-Chris

 

[djones44]

However, it's unlikely the tank is the source of your odor in your salon unless it's coming in through an open window on the same side as the tank vent thru-hull. Otherwise the most likely source is permeated sanitation hoses.

I took Peggie's standing advice about permeated sanitation hoses, and it cleared the odor at once. Of course Twilight has a Raritan system, so no holding tank per se to consider.

Lessons learned:

1) If you have black rubber/metal mesh hoses, get out your Dremel and just cut them off, get the hose clamps off later. They are a bear to remove in close quarters.
2) I had a Y valve above the water line and it had to go, too.The whole conduit system was down to 1/2" I.D. instead of 1.5" and everything was silted or calcified up. Brown color too...
3) In raw water systems remember that fine sand or mud is always accumulating, it may have been the boat's PO's had used abrasive cleaners like Comet, leaving insoluble talc to fall back down each flush and destroy your macerator pump five times sooner than necessary. Scrub with rock salt if you must.
3) The new white hard plastic ones are indeed far less permeable, a few dollars a foot, and soaking them in boiling water (or heat gun?) makes them take corners much more readily and securely during installation.

Thanks once more to Peggy - sanitation hoses in my mind need replacing, period, if they are the old heater type black ones. Chemicals should be tried last.

 

[CapnCrunch]

I havent read all the responses, so please forgive me if this post is redundant.

Your problem is what folks round here call a "boat fart" which is characterized by a distinctive acrid stench. I have had problems with them getting into the cabin three times and all three involved the vent.

The first time, a dirt-dauber had blocked the vent at the hull fitting. The second time, I had overfilled the tank allowing some of the muck to get into the vent fitting at the tank. When the muck dried, it blocked the vent. The third time, I had replaced the old marine air unit (located in the bilge area) with a larger one during the summer and suddenly the boat fart would get in the cabin when the toilet was flushed while the a/c was running. It turned out that the return air vent between the cabin and the bilge was too small, forcing the a/c unit to also pull in outside air through the engine room vents in the hull. One of these vents just happened to be right next to the holding tank vent, so the boat fart was getting sucked into the boat and circulated by the a/c fan. A larger return air vent in the cabin floor solved the problem.

Your problem could also be caused by switching from a manual toilet to an electric one because the electric forces a larger volume through the hoses at a faster rate, thus overwhelming your tank vent.

If you can smell a very foul odor outside the boat when someone flushes, your problem is probably not the vent. Another test is to observe the holding tank while someone flushes - if the tank appears to "balloon" outward, your vent is blocked. Yet another symptom of a blocked vent is the presence of foul-smelling bubbles in the toilet water for a minute or so after each flush.

Many boaters find that trying to suppress/eliminate tank odors can be an expensive and often futile endeavor. Putting up with boat farts - which usually dont last long - is IMHO just part of life afloat. :lol:

Finally: If the odor you are experiencing is more of a rank smell than the one described above, your problem is more than likely due to "permeable" waste system hoses. If your waste system uses flexible hoses between the toilet(s) and the waste tank, you will eventually have a permeation problem. You can make the hoses last longer by always flushing enough water through the system to ensure that no waste remains in the hose. However, this tends to fill the tank much more rapidly. One great solution to the hose problem is - if possible in your boat - to replace the flexible hose with rigid PVC which is impermeable. The other is to use a marine sanitation hose like that made by Vetus. The downside of this is that the product is pretty expensive ($7+ per foot) and doesn't last forever. If you do choose to replace with hose, wrap it with aluminum tape, if possible, because aluminum is also impermeable.

Hope this helps