Update:
Replaced the large tank hoses with higher quality rubber hoses and the smell is diminished. There is still a reminder of the holding tank i the areas near the tank itself.
Also, the 33-2 holding tank has a design flaw (my opinion) that reduces the effective capacity of the tank.
- her holding tank has its inlet in the upper port corner. On a starboard tack the effluent level in a partially fuilled tank will rise above the inlet, backfulling the head's hose. If the joker valve leaks, the effluent fills the head with each tack, and eventually it will slop out of the head.. The holding tank's inlet pipe should have been on the tank's centreline.
Original 2016 Post:
A discussion recently on the Stus list - the C&C email mailing list, piqued my curiosity about my piquant holding tank and related hardware - for background, I had replaced head and hoses, and had removed the tank for repair. Despite numerous washings with bleach and other hopeful chemicals, it still stank. perhaps a lost cause, but I had hoped (and continue to hope) that with proper hoses and ventilation, the smell will be contained to the tank.
My new and 'proper' hoses fail the sniff test, now, one season later. Apparently there is a much better grade that is non permeable. Also, my tiny original vent hose is probably partially blocked, and regardless, is hardly more than a means of ensuring the tank remains at atmospheric pressure.
he upshot of the discussion appears to be this:
Get the best hoses, non permeable.
Ensure that the waste cannot decompose anaerobically, meaning, ensure it gets plenty of oxygen. The vent cannot do this. Other do this either passively (larger and multiple vents) or actively (an aquarium type bubbler, or oxygen tablets.)
My original question:
From: Dave Syer <syerdave@gmail.com>
> ventilation are main keys. A real eye opener for me was finding
> a bug nest clogged air vent line, so at the very least check or
> replace your vent line. To be honest, I cannot make any claims that
> adding the active ventilation fixed any problems as the system was be newly
> installed so there was no problem to fix. But at such a small
> cost ~$25, it was a no brainer to install a system which constantly
> pumps fresh air into the holding tank. I thought briefly about
> getting a 12V air pump, but if I were to make any changes it would be to plumb
> the galley sink drain to the head inlet so that when I leave the boat
> for an extended period,
> the head inlet could easily be flush with fresh water. This
> eliminate salt water organisms from the inlet line which die off in
> the line and decay, without oxygen, anaerobically.
> Paul E.
> commented that he liked the location because he could hear the vent.
> So, it is admitting some air, but day in day out, not a lot because it
> can't circulate.
> Any reason you can think of not to create a vented deck fill? Big
> boats have big vents... Same thing, I would think.
> This may not solve the stench-permeated tank issue, but it would air
> the tank.
created by the pump. Mine was the same way when I bought my boat so I
added a second and enlarged the first using 1-1/8 SS thru hull fittings
and hose. was not that big a job. also the waste hose could be a big
source of smells from the system. I replaced all those as well. no
oder at all on our boat!
opening and get the tank nice and clean.
Cc: "Andrew
Date: Mon, 15 Aug 2016 09:42:23 -0400
From: "Marek
Further to that discussion, a reference to Peggie Hall ("The Headmistress") on a powerboating website "ask the experts" page - covers hoses:
And don't forget the vent lines. They should be as short, straight, and horizontal as possible; five feet is a good length. Hall recommends using a one- or even a 11⁄2-inch-diameter vent rather than the standard 5/8 inch, even though it means using a nonstandard fitting in the topsides. "I'm not a fan of vent filters, either. The filter impedes the free flow of air, which you need for odor control."
Once you've decided on a location, find a tank to fit the space. "Ronco Plastics
has over 400 shapes and sizes; they're the best source on the planet for water and holding tanks," says Hall. Ronco will install the fittings you want, where you want them. "I prefer two discharges, because it eliminates the Y-valve—one less thing to break. Ideally the inlet, outlets, and vent should be on top of the tank, which eliminates standing waste in the hoses," she explains. "However, that requires at least five inches of clearance above the tank, which isn't always possible." Top-mounted fittings let you disconnect the hoses without spillage even if the holding tank is full. "Have you ever known a macerator to fail when the tank wasn't full?"
Finally invest in top-quality hoses. Hall recommends just two brands: Trident Sani Shield #101 and #102, double-walled hoses with high odor-resistance; and SeaLand. "Double-clamp everything, with the clamp screws on opposite sides of the hose," she notes.
My new and 'proper' hoses fail the sniff test, now, one season later. Apparently there is a much better grade that is non permeable. Also, my tiny original vent hose is probably partially blocked, and regardless, is hardly more than a means of ensuring the tank remains at atmospheric pressure.
he upshot of the discussion appears to be this:
Get the best hoses, non permeable.
Ensure that the waste cannot decompose anaerobically, meaning, ensure it gets plenty of oxygen. The vent cannot do this. Other do this either passively (larger and multiple vents) or actively (an aquarium type bubbler, or oxygen tablets.)
My original question:
From: Dave Syer <syerdave@gmail.com>
To: "dreuge@gmail.com"< dreuge@gmail.com>, C&c Stus List
<cnc-list@cnc-list.com>
Subject: Re: Stus-List Guidance required on Sewage hose type - LF38
NOW Active holding tank vent
Paul ? great blog, lotsa detail. You have piqued my curiosity with your active holding tank vent project. I have a rather ?piquant? poly holding tank in my 33-2. I changed the in and out (but not the vent) hoses and still I get a stench, particularly when the adjoining lockers are opened. The tank itself was removed and repaired, and while out it could not be de-stinked by any means I attempted, bleach, etc. Maybe there?s a way to deal with that, dunno.
Am considering replacing the tank, but would rather resolve the cause. (or do both, and make provision for better/active ventilation in the new tank)
In your post below, you seem pretty pleased with the result, any other insights? Anything you would do differently?
Dave
> Dave,
>
> From what all the experts say, using quality hose and having proper > ventilation are main keys. A real eye opener for me was finding
> a bug nest clogged air vent line, so at the very least check or
> replace your vent line. To be honest, I cannot make any claims that
> adding the active ventilation fixed any problems as the system was be newly
> installed so there was no problem to fix. But at such a small
> cost ~$25, it was a no brainer to install a system which constantly
> pumps fresh air into the holding tank. I thought briefly about
> getting a 12V air pump, but if I were to make any changes it would be to plumb
> the galley sink drain to the head inlet so that when I leave the boat
> for an extended period,
> the head inlet could easily be flush with fresh water. This
> eliminate salt water organisms from the inlet line which die off in
> the line and decay, without oxygen, anaerobically.
> Paul E.
> 1981 C&C 38 Landfall
> http://svjohannarose.blogspot.com/
On 8/14/2016 7:45 PM, Syerdave--- via CnC-List wrote:
> Thanks Paul, you've got me thinking....
> I know the vent works because the guy who did the last pump out > commented that he liked the location because he could hear the vent.
> So, it is admitting some air, but day in day out, not a lot because it
> can't circulate.
> Any reason you can think of not to create a vented deck fill? Big
> boats have big vents... Same thing, I would think.
> This may not solve the stench-permeated tank issue, but it would air
> the tank.
> Dave.
Message: 1
Date: Mon, 15 Aug 2016 09:33:12 -0400
From: Danny
HI Dave,
Not for nuthin' but, if you can hear the the vent, it is
restricted and
won't be letting much air in unless there is a vacuum like
the one created by the pump. Mine was the same way when I bought my boat so I
added a second and enlarged the first using 1-1/8 SS thru hull fittings
and hose. was not that big a job. also the waste hose could be a big
source of smells from the system. I replaced all those as well. no
oder at all on our boat!
The larger vents and thru hull also allow me to flush the
system at
pumpout with fresh water running into the system through the
vent opening and get the tank nice and clean.
Danny
Cc: "Andrew
> Sent: Monday, August 15, 2016 07:46
> Subject: Re: Stus-List Guidance required on Sewage hose
type - LF38 NOWActive holding tank vent
>> I flush an oxygenater tablet into the holding tank
every few weeks. That has completely eliminated the smell we once had from the
holding tank.
This is one source.
>> Andy
Message: 2From: "Marek
Dave,
not a specific solution to any of your problems, but if you
are dealing with sanitation, Peggy Hall?s book (Get Rid of Boat Odors) is a
very good read. It might be the best $25 you spend on your sanitation systems
(A Kindle version is I think under $10).
Marek
Further to that discussion, a reference to Peggie Hall ("The Headmistress") on a powerboating website "ask the experts" page - covers hoses:
And don't forget the vent lines. They should be as short, straight, and horizontal as possible; five feet is a good length. Hall recommends using a one- or even a 11⁄2-inch-diameter vent rather than the standard 5/8 inch, even though it means using a nonstandard fitting in the topsides. "I'm not a fan of vent filters, either. The filter impedes the free flow of air, which you need for odor control."
Once you've decided on a location, find a tank to fit the space. "Ronco Plastics
has over 400 shapes and sizes; they're the best source on the planet for water and holding tanks," says Hall. Ronco will install the fittings you want, where you want them. "I prefer two discharges, because it eliminates the Y-valve—one less thing to break. Ideally the inlet, outlets, and vent should be on top of the tank, which eliminates standing waste in the hoses," she explains. "However, that requires at least five inches of clearance above the tank, which isn't always possible." Top-mounted fittings let you disconnect the hoses without spillage even if the holding tank is full. "Have you ever known a macerator to fail when the tank wasn't full?"
Finally invest in top-quality hoses. Hall recommends just two brands: Trident Sani Shield #101 and #102, double-walled hoses with high odor-resistance; and SeaLand. "Double-clamp everything, with the clamp screws on opposite sides of the hose," she notes.
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