Time to tackle the holding tank - yuck

F

footloose

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Looking to purchase a 30-40 gallon holding tank and mount it in the rear of the engine room since I can't squeeze it where the shoebox sized one is now. This means the tank will be down stream and down hill about 12 feet from the head. Any problem with that? I have the electric pump and raw water flush today.

Thanks for inputs as usual.
 
I would say even on my little cruiser the run is 12 feet and I have a manual flush, so no. My pump out is on the transom is that what your doing? I like it back there.

Good luck
Niles
 
Just be sure to have a good-sized vent line; don't go with the standard 1/2" or 5/8" vent line that many boats have as standard from the builder. Go with a 3/4" or larger diameter vent line coming out of the tank. Even if you have to put in a new through-hull for the vent line to exit the boat, it'll be well worth it. The more air that can come out of the tank as it fills, and come into the tank as it empties, the better.
 
the longer the hose run, the more stuff stays in resulting in stinky hoses after a while but there is not much you can do. i have a good 30' between the aft head and the tank at the bow, with the vac. pump halfway down the run, works fine.

Vi, since vent is so critical, i wonder why no one has come up with a vent fitting that woudl screw in the pump out fitting ? maybe even have a small solar fan in there... that woudl increase air flow in the tank.
 
yeah - my pump out is above the existing tank so about 8 feet forward of the transom. I will leave it there I think and since the tank will be bigger, I can flush a little more as needed. Thanks folks....Pascal, patent that buddy and retire.
 
Pascal quote:
'Vi, since vent is so critical, i wonder why no one has come up with a vent fitting that woudl screw in the pump out fitting ?'

The pump-out fitting hose connects to the bottom of the tank whereas the vent hose is connected at the top.
David
 
I have a question for ya'll . . . . if, as Vic suggests, a 3/4" vent line from the holding tank to the outside world is a good idea . . . . does anybody have a suggestion on what to use as the vent hardware on the hull? I notice that in the Boatfix, WM and BW catalogs, the only sizes for vent hardware are 1/2" and 5/8". I will offer my $20.00 testimonial payment from Raritan (payable in 40 equal payments over 40 years), as promised by Vic, to the best suggestion on the vent hardware.
 
quote:
Originally posted by Sailboattraitor

I have a question for ya'll . . . . if, as Vic suggests, a 3/4" vent line from the holding tank to the outside world is a good idea . . . . does anybody have a suggestion on what to use as the vent hardware on the hull? I notice that in the Boatfix, WM and BW catalogs, the only sizes for vent hardware are 1/2" and 5/8". I will offer my $20.00 testimonial payment from Raritan (payable in 40 equal payments over 40 years), as promised by Vic, to the best suggestion on the vent hardware.

Click to expand...

Use your 3/4" hose for the run from the tank.

Stick one end of a barbed nylon 3/4" to 1/2" hose splice fitting inside the far end.

Stick about 2" of 1/2" hose on the other end of nylon fitting.

Attach the other end of the 1/2" hose to a 1/2" barbed through-hull fitting.

The short length of 1/2" hose and 1/2" fittings will not restrict airflow that much.

They call them "straight hose mender" on this page, but you get the idea. http://www.grnleafinc.com/Catalog/GLHose.html Common item found in almost any good hardware store.
 
The best thing to do is use a conventional mushroom-type through hull fitting that you'd use for a bilge pump or air conditioning pump. Just mount it high on the side of the hull, up near the toe rail. If you reduce the hose down in size to accomodate an existing through-hull fitting, you aren't really gaining anything.
 
Vic has it. It's a through hull thingy with a barbed 3/4" hose fitting that you want. Bronze or plastic. Just try to find one online, though...
 
LOL. I spent 10 minutes looking in the BoatFix online catalog without success. I even tried searching "through hull" and got nada. I just searched "thru hull" and found it the first time!
 
Took me a while to find it, too. I guess "through-hull" and "thru-hull" can mean two different things (?) Maybe like "disc" and "disk".
 
While more expensive, wouldn't a Lectra San (sp?) be more effective in the long run?
 
Just a little more info, CONBRACO has 90`Bronze thru-hulls up to 2" hose.
Attwood has plastic 90`thru-hulls up to 1.125"
 
Technically, a holding tank's vent line through-hull fitting is supposed to have a spark arrestor screen in it, just like a fuel tank vent. That's in case someone wants to try and "light off" any escaping methane gas coming out the vent. (Guys, remember the old college dorm days, being rolled up in a ball on your bed with a lit match behind your rear end - waiting to expel some gas - and vying to see who could make the biggest flame? I doubt you'll see any reference to this on the Women Only Forum - it's strictly a "guy thing" [:-party] - they don't know how to have any fun.)

Anyway, getting back on the subject, larger fittings aren't made with spark arrestors inside, so the boat builders simply use an additional fuel tank vent fitting for the holding tank's vent, either in 1/2" or 5/8".

But from a practical standpoint, they're too small to do any good. Plus they are a magnet for mud daubers, who like to build their nests in the fittings, blocking them off completely - so that there's absolutely no venting at all... In most cases, the first thing marine plumbers do, when they're checking the holding tank's vent through-hull, is to take an ice pick and rip the screen out - to allow better venting and to take away the mud daubers' nesting area. So the spark-arresting screen soon becomes a thing of the past anyway.

Being an old back yard mechanic, I tend to go with "what works," rather than necessarily following all the politically correct methods. If you use a conventional mushroom-type through hull fitting, it will work - and that's what's important... Being realistic, I've heard of holding tanks rupturing or bursting because of a plugged-up vent line. But has anybody EVER heard of a holding tank catching fire, or exploding, from methane gas being ignited? I haven't.
 
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