Smelly Boat? - One more place to look!

[Barrie]

My old boat was a full keel but fortunately came with a drain plug located right at the bottom of the keel. Have no idea how the water got in but at haul out time about 5 gallons of the smelliest water glugged out.

 

[Mako]

You're planning to run two vents, one to each side of the boat? If so, either put the thru-hulls at least 2' above waterline with oversized clamshells over 'em, facing the "wrong" way to act as air scoops when the boat is underway or on an anchor

not sure if you typed that up correctly, but wouldn't you want one clamshell facing forward (providing slight positive pressure) and one facing astern (slight negative pressure due to Venturi) so that you achieve a modicum of actual airflow across the holding tank?

If both clamshells face rearward then there would be nearly no airflow... stagnation.

 

[Doodie99]

So after an 19 year layup with some water getting in the bilge it became a bit rank. i drained the skanky water out and rinsed it several times. after put enough water in there to cover the areas stained with a mixture of concentrated simple green. I let it soak for a while. I drained it and rinsed more . It made a significant difference in the odor in there.

 

[Symphony]

Here’s a great dry bilge diy
https://lifeempirically.com/2018/03/12/build-your-own-diy-arid-bilge-or-dry-bilge-system/

 

[HeadMistress]

If both clamshells face rearward then there would be nearly no airflow... stagnation.

If that were true, there'd be no air exchange via a single vent.


--Peggie

 

[GB32Patience]

Love that economical dry bilge system Symphony! I had looked into the more complex and expensive packages and went for the sump.... this, I may incorporate.. Thanks!

 

[Symphony]

Yes, the commercial one is very nice and a great idea but VERY expensive for what it seems to be. And the work to install it is the same as this guy’s diy idea.

 

[Mako]

If that were true, there'd be no air exchange via a single vent.

There is very little air exchange.

A slight pressure differential is required in order to induce air FLOW. So one each, forward and rearward facing clamshells, will provide that.

The only air flow with a single vent might occur during the sloshing of waste in rough conditions. Otherwise the transfer of oxygen will basically be via osmosis, which is slow and ineffective.

I know from my own smelly experience that even though all boats have a small vent in their holding tanks, that the bacteria are growing in an anaerobic environment due to the lack of oxygen. Hence the need for larger vent lines or double vents, as you correctly espouse.

Funny how Brevard County is just now discovering this and had my father replace his septic system (on the Banana River) with a new system with forced air flow.

 

[HeadMistress]

I'm sure you know much more about holding tank and other boat odor issues than I do...I've only specialized in marine sanitation with an emphasis on odor prevention/elimination for 30+ years.


--Peggie

 

[Mako]

This isn’t a pissing contest of credentials, Peggie. I thought my point was clear, but I suppose not.

If we want beautiful, yummy happy aerobic bacteria in our holding tanks, instead of those gross smelly anaerobic bugs which many of us have suffered with, then we need oxygen. We need air transfer, which I believe is better accomplished with 2 opposite facing clamshell vents, yielding slight positive and negative pressures.

You don’t think that’s true. I can’t see why not, but fine.

 

[Bmarler]

I'm sure you know much more about holding tank and other boat odor issues than I do...I've only specialized in marine sanitation with an emphasis on odor prevention/elimination for 30+ years.


--Peggie

i doubt anyone would claim to know more about those subjects than you do, however, there would in fact be more flow across a tank where one vent aims forward, and another aims aft. these would need to be separate penetrations in the tank to make the most exchanges of air possible.
what i don't know is, is it bad to have too much exchange of air? maybe a slower flow is better? this is where your expertise comes in. any time you have to modify a system as opposed to designing from a clean sheet there are questions an expert like yourself can answer easily.

 

[HeadMistress]

I pioneered aerobic holding tank management in the late '80s... I KNOW it's possible with just a single vent. And tanks DO "breathe!" More difficult when the vent line is only 5/8", but still very possible if the vent line is straight, doesn't rise more than 45 degrees off horizontal and the right tank product--one that works WITH nature instead of poisoning bacteria--is used. We introduced the first one in the late '80s...a bio-active (live bacteria) product that we named K.O...it became Raritan K.O. when Raritan bought my product line in 1999.


You might consider picking up a copy of my book (see link in my signature...just click on the title)...you might learn something.


--Peggie

 

[Bmarler]

I pioneered aerobic holding tank management in the late '80s... I KNOW it's possible with just a single vent. And tanks DO "breathe!" More difficult when the vent line is only 5/8", but still very possible if the vent line is straight, doesn't rise more than 45 degrees off horizontal and the right tank product--one that works WITH nature instead of poisoning bacteria--is used. We introduced the first one in the late '80s...a bio-active (live bacteria) product that we named K.O...it became Raritan K.O. when Raritan bought my product line in 1999.


You might consider picking up a copy of my book (see link in my signature...just click on the title)...you might learn something.


--Peggie

please don't think i' trying to be argumentative, i'm not.
i wasn't trying to debate your knowledge of how sanitation systems work, i was only pointing out that the vent arrangement described does indeed provide more exchanges of air. what that does for a holding tank is a question that i would leave to you.
i am considered an expert in my field, just as you are. but there are always small things to discuss, some have little effect, some have no effect, but sometimes there is something new to be learned. i try not to close myself off to these discussions.
and i do plan to get a copy of your book, i'm sure i would find it useful.

 

[SP3]

I have a smell in the boat and been reading these posts, ducking into the hatch, checking out options - I always find a flaw with the plan, so I stuck a carbon filter back on the vent and well, lets just say it helped... a little.

So we have a pump type toilet that brings in water from the sea (salt). The vent piping has been reduced at the threads on the tank to what looks like garden hose type threads (I assume 5/8). Loops around to the carbon filter then up through the floor and out a gasoline type vent, well above the waterline and in a place I am not sure how to get to without removing finished walls in the head.

I am all in on the aerobic digestion idea at this point, but I have a few problems. One, maintaining a clear 45 degree angle to get several feet above the waterline to put a vent in is not going to happen easily. There just isn't easy access to make this run, keep the pitch, and avoid sharp angles in the line.

Ideally I would go straight out the side, but if I pin the pipe against the top of the hatch ceiling I may get about 9" above the water. So if I go this route, I would want to go lower still so that if water gets scooped up in rockin water, the scooped up water would likely run back out for the most part instead of into the tank. There would be a high point of a few inches between the tank and the mushroom. To be honest, I don't think it would hurt anything if outside water did get in as it would just go in the tank until there was not room.

So I had a few solutions. Run the vent along the ceiling and drop down and out the hull above the waterline 6" and put a valve that could be closed in the case of bumpy seas and hook the existing vent pipe into that to keep things still workable. This of course is subject to operator error.

The second option would be to run a through vent line from port to starboard and have the vent from the tank drop down a few inches into the cross vent. Then if water comes in while rocking on the beam, it can just pass to the opposite side and out the opposite side of the boat without going into the tank.

The existing pump outs on the gray and black tanks are lower than where I would punch the vents out and have yet to have a problem, so I think I can get those in so that there is not a problem with seepage around the mushroom vent.

Thoughts? Have I spent too much time in the fumes in the hatch with the holding tank?

We have to pretty much air out the boat currently which hasn't been a problem when it has been warm, but soon it will be winter, and we have noticed the smell has some staying power on things (like towels) so we want to reverse that ASAP.

Thanks!

 

[Symphony]

Dear SP3,Before you do a lot of surgery to install vents, try using fresh water to flush. You can just get a bottle you fill with water from the hose. After using the toilet dump in a glug of water from your bottle and pumpout to your holding tank. Do not pull in seawater.


Try that for a couple of days and I bet you will decide to plumb fresh water to your toilet.
Good luck because getting rid of that odor is one of the single best improvements you could make to a live aboard vessel.

 

[Comodave]

SP3, if you aren’t able to get good vent runs, plural preferably, then look at an aerator system like Groco Sweetank. It pumps air into the tank continuously so having multiple or large vents isn’t necessary. We had a horrible smell in a previous boat about 20 years ago. Peggie turned me onto Sweetank and it made an amazing difference. After installing it we never put any chemicals into the tank for the 8 years we owned the boat.

 

[Bacchus]

Here is a link to my website and a summary of my DIY tank aeration project.
The only change I made was to replace the dip tube with PVC. This solved my very bad smell problem.
https://dkloeber.wixsite.com/bacchus/projects-pg-2
You may get an initial smell if salt water has been left in the pick up hose for an extended time.
I have since found a way to run a straighter vent hose to my bow but believe belt & suspenders never hurt.

 

[koliver]

Before replacing my entire black water system I read all the advice here and heeded Peggy's advice. At first I thought there would be no way to route a 1.5" vent successfully, what with all the things in the way and the long run from the tank location to available access.
I allowed a couple of friends aboard to look at the location and to suggest alternative routing for the vent. Eventually I came back to my first inclination, to route the vent through the fwd hanging locker so as to achieve a position on the side of the hull that was high enough, and to which the vent would fall the last few inches, so if there ever was a tall enough wave at that location, it would most likely not end up running into the tank.
I used hard pipe, 1.5" inside diameter, with a mushroom through hull fitting that is over 24" above the resting WL. Installation would have been so much easier with the use of an extra joint between my wrist and elbow, and an extension of my wrist. Awkward in the extreme, but using hard pipe, I was able, with a second person, to hold the horizontal piece that went between the floor and the stringer in place while the helper jammed the vertical into the angle fitting far enough for a good seal. Oh the advantages the builder has, to put this sort of thing together before the interior goes in!
Hard pipe will never allow anything to sit in the line, so will not make any contribution to smell. The old vent was rubber hose, attached at the tank through a 1/2" bronze fitting and at the hull through a vent exactly the same as the one on each of the water and fuel tanks, bug screen and all, so effectively 1/8" diameter. No wonder it allowed a bad smell!
If you take nothing else from this, at least use hard pipe to eliminate sags, and go to as large a diameter as you can fit.

 

[GB32Patience]

@Bacchus, Nice simple solution there for the bubbler. Great job on your project documentation website as well. Once we solved our hidden bilge space problem, our smell cleared up. With only a small (20gal) holding tank that gets pumped frequently, fortunately we have not had to deal much with head odors. Some longer trips next season may change our tune on that! Thanks for solution!

 

[HeadMistress]

All of you who are trying to eliminate odor INSIDE your boats by improving tank ventilation or aeration or a particular tank product are just chasing your tails...'cuz nothing you do to a holding tank--aeration, tank product, venting, filters--has any impact on odor INSIDE a boat because unless a tank is leaking, odor from inside the tank has only one place to go: out the tank vent (or, if the joker valve is worn out) into the toilet.

The most common sources of odor INSIDE a boat are permeated sanitation hoses and wet dirty bilges and sumps, but don't rule out leaking hose connections or the chain locker.

Odors are always strongest at their source, so "head" related odors will usually be confined to the head as will a dirty shower sump. Permeated hoses will also permeate every area they pass through with residual odor. A wet dirty bilge is a primordial soup that can make a whole boat smell like a swamp or even a sewer. Same is true of trapped water, which can sometimes be hard to find...but when you've eliminated every other possible source, what's left has to be be the answer.


--Peggie

 

[SP3]

Thanks all for the replies. The odor is strongest in the hatch with the tank. Since there are several holes in the floor going several places, and the hatch has openings into the engine room, it is getting around, but definitely the strongest in that hatch. Both Gray and Black tanks. I'll try the boiling water and wash cloth trick on the hose. They are sanitation hoses, according to the label, but are are at least 12 to 14 years old when the boat was rebuilt and maybe not the best product. We don't get a strong smell in the head.

Is the salt water a deal killer on getting a healthy tank, I know all the critters are dying in there too, but it why would it permeate if there are no leaks?

The boat has packing at both the drive shaft and rudder that allow some drips to come in the boat, so there is always some water in the trough in the bottom.

We don't live aboard.

 

[HeadMistress]

Is the salt water a deal killer on getting a healthy tank, I know all the critters are dying in there too, but it why would it permeate if there are no leaks?

You lost me with everything after "Is salt water a deal killer..."

Sewage is so full of bacteria that the tank doesn't even notice whether flush water is salt or fresh. But the toilet discharge hose is another matter. Salt water is full of micro and not-so-micro animal and vegetable sea life that, when allowed to die and decay in a hose, stink. Those who claim that they have less HOLDING TANK odor after switching to fresh water flush could have accomplished that by simply following to each sea water flush with a quart of fresh water.

--Peggie

 

[SP3]

Thanks Peggie - I couldn't imagine why the biomass in the salt water would make that huge of a difference to not be tenable to use, but I have seen that comment from several folks, so the switch must have worked for some. I like the simple solution of dropping some fresh water in, I have added the sodium bicarbonate before and it seems to help, maybe because it simply cleaned out the pipe temporarily.

I will try the new hoses before messing with vents. Should be fun. Heres some pics of the tank.

 

[dhays]

Thanks Peggie - I couldn't imagine why the biomass in the salt water would make that huge of a difference to not be tenable to use, but I have seen that comment from several folks, so the switch must have worked for some. I like the simple solution of dropping some fresh water in, I have added the sodium bicarbonate before and it seems to help, maybe because it simply cleaned out the pipe temporarily.



I will try the new hoses before messing with vents. Should be fun. Heres some pics of the tank.

I think you need to decide if you are getting a sewage from from permeated hoses (a strong possibility) or if you are just getting the smell from the stale sea water that is sitting in the intake hose.

My experience is limited, but the smell from the raw seawater that has been sitting in the intake hose will be strong at first flush (rotten egg smell in my experience) but will not recur while the boat is being actively used and will return on the first flush say the next weekend.

Smell outside the boat can be addressed with better venting, or as Bacchus did, adding aeration to the holding tank.

 

[wkearney99]

It helps to avoid having any dips in the hoses were water can pool. Especially on the vent lines. A vent needs air and water collected in a low spot on the hose may be enough to block the flow. Like a trap provides under a sink. This leads to the tank not getting vent air and increased stink. I had that problem in our EB47. When I cleared the line of water and secured it such that it had no dips then the smells stopped being a problem.

 

[koliver]

It helps to avoid having any dips in the hoses were water can pool. Especially on the vent lines. A vent needs air and water collected in a low spot on the hose may be enough to block the flow. Like a trap provides under a sink. This leads to the tank not getting vent air and increased stink. I had that problem in our EB47. When I cleared the line of water and secured it such that it had no dips then the smells stopped being a problem.

Hard pipe will never allow anything to sit in the line, so will not make any contribution to smell.

 

[wkearney99]

Hard pipe will never allow anything to sit in the line, so will not make any contribution to smell.

Any carrier, properly installed, wouldn't allow pooling. It's entirely possible to do a poor job installing anything, including 'hard pipe'. That and using hard pipe is perhaps more problematic than might be obvious to some. Boats have a fair bit of vibration and over time that can be bad for hard connections. With tubing and cables you risk chafing, so it's not without challenges either. Upside to tubing is you can generally run it through and around and not have to put any connections in the line.

Whatever you choose, know the proper ways to install it and how to maintain it over time.