I just read Peggie Hall's article on head odors, and am wondering what the best way to improve holding tank air circulation on my '84 C-30 would be. I just got this boat, and understand that the holding tank vent comes out onder a stantion post - obviously not good for keeping fresh air in the tank! Should I install another vent line, and if so does anyone have any suggestions on how & where to install it. The holding tank is under the port side setee, aft of the head. Thanks, Roger Noble Austin, Texas
- Status
- Not open for further replies.
T
tom
Good question.
Seems that adding an additional vent line is something that could benefit alot of folks. Get a little cross ventilation. Is there some type of kit available for this or would you just drill a hole in the tank and run a line to another thru hull vent? Are there parts available to add another vent outlet to the holding tank? Thanks.
Seems that adding an additional vent line is something that could benefit alot of folks. Get a little cross ventilation. Is there some type of kit available for this or would you just drill a hole in the tank and run a line to another thru hull vent? Are there parts available to add another vent outlet to the holding tank? Thanks.
P
Peggie Hall/Head Mistress
I'd do a couple of things...
Re-route the existing vent line to a new through-hull that will allow some air to travel through it...making the line as short and straight as possible...take out any loops or traps. There are a couple of ways to install a new vent fitting...both require access to the inside of the tank through an inspection port. If your tank doesn't have one, WM sells retrofit kits that are inexpensive and easy to install. If you have a couple of inches of clearance above the tank, you could just drill a hole in the inspection port cap and cement a fitting into it...But since no sealant will bond permanently to polyethylene, the only way to install a new fitting in the wall of the tank itself is to use a bulkhead through-hull and put a gasket under the nut to seal it. Just be sure when you drill the new hole that it's a VERY tight fit for the fitting. Whether on the top or the end, vent fittings should always be on the side of the tank closest to the centerline of the boat...so that the tank contents can't over flow while heeled. And when running the line to the hull, just remember that it should be as straight and as horizontal as possible..a foot or so longer is better than than a shorter hose that goes straight up...and it should be a 1" ID hose. If you have any more questions about how to do this, I'll try to walk you through it.
Re-route the existing vent line to a new through-hull that will allow some air to travel through it...making the line as short and straight as possible...take out any loops or traps. There are a couple of ways to install a new vent fitting...both require access to the inside of the tank through an inspection port. If your tank doesn't have one, WM sells retrofit kits that are inexpensive and easy to install. If you have a couple of inches of clearance above the tank, you could just drill a hole in the inspection port cap and cement a fitting into it...But since no sealant will bond permanently to polyethylene, the only way to install a new fitting in the wall of the tank itself is to use a bulkhead through-hull and put a gasket under the nut to seal it. Just be sure when you drill the new hole that it's a VERY tight fit for the fitting. Whether on the top or the end, vent fittings should always be on the side of the tank closest to the centerline of the boat...so that the tank contents can't over flow while heeled. And when running the line to the hull, just remember that it should be as straight and as horizontal as possible..a foot or so longer is better than than a shorter hose that goes straight up...and it should be a 1" ID hose. If you have any more questions about how to do this, I'll try to walk you through it.
R
R. Palaia
Peggie, I'm doing the same thing
Hi Peggie, I plan to install a new vent because my current vent also is run to a stanchion. When I spoke to you in Annapolis, you suggested to use 5200 to seal the new fitting onto the inspection port cap. Will a gasket be better??? I plan to run the new vent line forward and out to a thru hull fitting hidden by a v-berth cabinet. The current vent line is out of a stanchion more aft of amidships. Is it wise to move the existing vent line to a thru hull further aft (which would be in the area of the cockpit)???? Should holding tank vents not be near the cockpit?? Thanks, Roc
Hi Peggie, I plan to install a new vent because my current vent also is run to a stanchion. When I spoke to you in Annapolis, you suggested to use 5200 to seal the new fitting onto the inspection port cap. Will a gasket be better??? I plan to run the new vent line forward and out to a thru hull fitting hidden by a v-berth cabinet. The current vent line is out of a stanchion more aft of amidships. Is it wise to move the existing vent line to a thru hull further aft (which would be in the area of the cockpit)???? Should holding tank vents not be near the cockpit?? Thanks, Roc
P
Peggie Hall/Head Mistress
If no odor is coming out the vent...
It doesn't matter where the thru-hull is. The whole thought process behind putting vents away from cockpits was based on the false premise that a holding tank odor is inevitable. However, if odor IS coming out, it doesn't really matter anyway..'cuz if the thru-hull is upwind of the cockpit, it's gonna flow back to the cockpit. I like to position vent thru-hulls forward, so that air is forced down them while underway. As for sealing the vent fitting...my only point is: no sealant will bond to polyethylene...but the inspection port cap isn't poly, so just about any sealant--pvc cement, 5200, etc--will bond to it (just don't use silicone--silicone doesn't seal anything...it just fills space). But if you're more comfortable using a gasket, fine. Just keep in mind that the vent line(s) MUST be straight (and "straight" does NOT mean "straight for 2', then up 3' "...it means a straight shot all the way--NO turns!), should be under 5' long, and should not rise more than 45 degrees. If that's still not clear, e-mail me and I'll send you a picture.
It doesn't matter where the thru-hull is. The whole thought process behind putting vents away from cockpits was based on the false premise that a holding tank odor is inevitable. However, if odor IS coming out, it doesn't really matter anyway..'cuz if the thru-hull is upwind of the cockpit, it's gonna flow back to the cockpit. I like to position vent thru-hulls forward, so that air is forced down them while underway. As for sealing the vent fitting...my only point is: no sealant will bond to polyethylene...but the inspection port cap isn't poly, so just about any sealant--pvc cement, 5200, etc--will bond to it (just don't use silicone--silicone doesn't seal anything...it just fills space). But if you're more comfortable using a gasket, fine. Just keep in mind that the vent line(s) MUST be straight (and "straight" does NOT mean "straight for 2', then up 3' "...it means a straight shot all the way--NO turns!), should be under 5' long, and should not rise more than 45 degrees. If that's still not clear, e-mail me and I'll send you a picture.
C
Charlie
Hardware Question
According to Peggies thinking, I have the worst vent system and I can attest to the fact that it never worked well. first, the hose size is 58 OD and there are two 90 deg bends and one 45. Also the rise is around 3.5 ft and the total length is around 7 feet. I read her article and I agree that some changes are necessary. I think that I can shorten the run and there is more then enough room for a 1 inch ID hose. My problem is that I have not been able to locate an outside vent fitting that does not look like a mistake. I intend to contact Catalina but I was wondering if anyone knew of any other suppliers. I have gone West Marine and Boat US route, nothing at the store or catalog. Charlie
According to Peggies thinking, I have the worst vent system and I can attest to the fact that it never worked well. first, the hose size is 58 OD and there are two 90 deg bends and one 45. Also the rise is around 3.5 ft and the total length is around 7 feet. I read her article and I agree that some changes are necessary. I think that I can shorten the run and there is more then enough room for a 1 inch ID hose. My problem is that I have not been able to locate an outside vent fitting that does not look like a mistake. I intend to contact Catalina but I was wondering if anyone knew of any other suppliers. I have gone West Marine and Boat US route, nothing at the store or catalog. Charlie
P
Peggie Hall/Head Mistress
Don't look for VENT fittings...
The trouble with "vent" fittings is that they all assume the same things: a 5/8" hose...and that they're all interchangeable with fuel, water or holding tank vents (a major shortcoming in the standards for boat piping is that it fails to take into account that holding tanks have absolutely nothing in common with water or fuel tanks). What you're really looking for is something called a "bulkhead fitting"...the same thing that your bilgle pump drains out of. Yes...I know that conventional wisdom--the same "conventional wisdom" that starts from the false premise that holding tanks have to stink--dictates that vent thru-hulls must have a screen in them to keep insects out and covers to keep water out...but the screen rusts--but not until after it's become clogged with dust, pollen and the occasional overflow...and there really is enough back pressure from a holding tank to prevent even a direct hit from breaking waves to allow more than an ounce or two to come back down the vent line into the tank. So so stop looking for a "vent fitting" and look for thru-hulls. The catalogs are full of 'em.
The trouble with "vent" fittings is that they all assume the same things: a 5/8" hose...and that they're all interchangeable with fuel, water or holding tank vents (a major shortcoming in the standards for boat piping is that it fails to take into account that holding tanks have absolutely nothing in common with water or fuel tanks). What you're really looking for is something called a "bulkhead fitting"...the same thing that your bilgle pump drains out of. Yes...I know that conventional wisdom--the same "conventional wisdom" that starts from the false premise that holding tanks have to stink--dictates that vent thru-hulls must have a screen in them to keep insects out and covers to keep water out...but the screen rusts--but not until after it's become clogged with dust, pollen and the occasional overflow...and there really is enough back pressure from a holding tank to prevent even a direct hit from breaking waves to allow more than an ounce or two to come back down the vent line into the tank. So so stop looking for a "vent fitting" and look for thru-hulls. The catalogs are full of 'em.
- Status
- Not open for further replies.