Holding tank vent locations

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
Just remember a reciprocating saw is your friend...
 
Comodave said:
Even if you could get a seal, wouldn’t the tube need to go down to the holding tank so it could get air into the tank in order to not collapse the tank?
Click to expand...


Yes. But it couldn't be IN the pumpout hose--it would be full of waste, which would clog the tube. So it would have to lie alongside it and somehow penetrate the top of the tank or the vent fitting on the tank, or...damned if I can figure out how it could possibly work without interfering with the seal. So I strongly suspect that it does, but the pumpout still might be able to pump out at least some of the contents given enough time. Kinda like sucking the last of a milkshake out of a cup with a straw...a lot of noisy slurping, but you can finally get most of it.



--Peggie
 
After tearing the boat apart and not finding a holding tank or two I started looking closely at all the labels on each tank, and I found this. Note the diesel and gasoline words scratched out. With a little more cutting I should be able to get to the fittings.

The Brockerts
 

Attachments

  • IMG_1424.JPG
    IMG_1424.JPG
    116.8 KB · Views: 86
Two questions: The name of the mfr? I can't quite make it out. What's the tank material?



--Peggie
 
Skyline Tanks INC. Alum 5052 .125" Thick I have found 2 of them, one on port side for Mid and forward head, that are both on the same vacuum generator, and one for the Master head on starboard side. Have not found everything for the master head yet.

The Brockerts
 
I hope that your holding tank isn’t aluminum. Aluminum doesn’t last too long as a holding tank.
 
Now that I have access to the top of the tank I can see the "full sensor" plate. If I remove that and look into the tank and check things out how would I reseal that sensor plate, 4200? 5200? or just some good quality silicone?

The Brockerts
 
The Brockerts said:
Now that I have access to the top of the tank I can see the "full sensor" plate. If I remove that and look into the tank and check things out how would I reseal that sensor plate, 4200? 5200? or just some good quality silicone?

The Brockerts
Click to expand...

I'd be very careful removing anything on the top of the tank if it's full.... The level may be above the top of the tank....
Maybe cut the vent line up as high as you can then/when doing a pumpout. Have a straight connector and a couple hose clamps to fit ready.
Usually any fitting on the tank will have some type of gasket. Most any gasket sealer will work at least until you can make another gasket.
I would not use 5200 or anything that would seal permanently.
 
What is the sensor plate made out of? I would go with a non permanent caulk like Sika 291. But Peggie probably is the person to ask. I wouldn’t use 5200 for sure. Some day you may need to remove it again. BTW, I would have an old shop vac at the ready. Also dump the shop vac and clean it out before in case you have to vacuum up some stuff it won’t be mixed with a bunch of stuff in the vac already. Good luck, better you than me...
 
Last edited:
Don't use any sealant. Instead use a rubber gasket to seal the flange--which should have been secured with about 6 small screws--and a rubber o-ring to seal the cap. Gaskets and o-rings are available from Beckson and other inspection port mfrs. Rubber dries out and cracks over time, so gaskets and o-rings should be replaced about every 5-6 years.

However, you have much bigger problem: aluminum holding tanks.

[FONT=&quot]In the 1980s when holding tanks began to be required on boats, aluminum and steel were the materials of choice because they were less expensive and easier to cut and weld in odd shapes than rotationally molded polyethylene. But although you’ll still find aluminum or stainless holding tanks on some boats, by the early 1990s, it had become apparent that any metal is a very bad choice for sewage holding because urine is one of the most corrosive materials it’s possible to put next to any metal. While the sheet metal walls of a metal holding tank may last up to a decade (rarely any longer once it’s actually put in use to hold sewage), metal waste tanks, even 316 stainless steel, will typically begin to leak at a seam or a fitting within two to five years. You may be able to repair it, but the first leak is always just the first leak; the bottom of the tank is gradually turning into a colander. Stainless steel will last a little longer than aluminum, but even the best 316 stainless holding tank rarely lasts more than 10 years no matter how diligent you are about pumping out and thoroughly rinsing out the tank every time you use the boat, never allowing waste to sit in it. Whether the toilet flushes with salt or fresh water makes no difference.[/FONT]
[FONT=&quot]
[/FONT][FONT=&quot]Some mfrs coated the insides of aluminum waste with epoxy, which extends its life a bit, but your photo makes it kinda obvious that it was made to hold fuel and re-purposed to hold waste, so it's unlikely that it was. [/FONT][FONT=&quot][FONT=&quot]The tank may have been mfr'd in '88, but had to have been repurposed a lot later than that or it would have turned into a colander long before now.
[/FONT][/FONT]
[FONT=&quot]So you're living on borrowed time before this tank begins to leak, maybe both tanks...we don't know yet what the other one is made of. You'd be wise to replace it with a top quality polyethylene tank before it does.
[/FONT]
[FONT=&quot]Ronco Plastics (no relation to the VegoMatic Ronco) [/FONT][FONT=&quot]Ronco Plastics marine Tanks is your best source. They make TOP quality thick-walled water and waste tanks for a very reasonable price and have more than 400 shapes and sizes, over 100 of which are non-rectangular, and they install fittings in the sizes and locations specified by the customer when they make the tank.
[/FONT]
[FONT=&quot]The only good news is, this can give you an opportunity to find a much more accessible location for the tank. In fact, if the drawing that you posted is an accurate depiction of your entire system, the plumbing is a mess! I'd pull the whole thing out and have it AND new tanks reinstalled correctly by someone who knows how to do it.
[/FONT]
[FONT=&quot]-Peggie
[/FONT]
 
Last edited:
I have a friend who was pumping out his new to him boat that geyserd on him. All over him. So be very careful about venting. I repurposed my direct overboard fitting to be a second vent after eliminating the Y valve. My next change will be to move the original vent closer to the tank with less opportunity for fluid holding dips in the hose.
Peggy, is there any reason not to use a regular mushroom shaped thruhull for the 5/8 vent line? I’m looking at having to replace the current vent because the screen is clogged with salt again. The potable water tank vent is clogged too, btw. I’m thinking I’d install a stainless steel mushroom type for the holding tank and one of those flush mount vents for the water. Even if I have to install a clamshell over the water vent it beats trying to keep the screens clear.
 
Brockets,
I have a 1990 45' Californian. The two vents on the port side midship are for the waste tank and fuel tank. I think the forward one is for the waste holding tank. I had a vent filter that was plugged due the Vacuflush toilet being flushed when the tank was full. I removed the filter and found the 5/8” vent hose to the tank plugged with the carbon contents from the filter. I routed out the hose and very CAREFULLY AND SLOWLY back flushed with the pump out port open. Only air came out. I then went to the pump out station, connected the pump out hose and could hear air being drawn into the vent. With the pump out running I wrapped a rag around a fresh water hose and held it to the vent. Thus completely flushing out the vent line. Based on Peggy’s advice I didn’t replace the the filter. Everything is ok now. But I think Peggy’s solution of having two large vent lines, one on each side of the boat to get cross flow of air is the ultimate solution.
Good Luck
 
Peggy, is there any reason not to use a regular mushroom shaped thruhull for the 5/8 vent line?

Nope...in fact, if you'd read my book (see link in my signature below) you'd know there's every reason TO replace the waste tank "vent" thru-hull with an open bulkhead or "mushroom" thru-hull...although in your case you can accomplish just as much by knocking the screen out of the existing thru-hull. As you're discovering, screens create more problems than they solve or prevent. An open thru-hull allows a lot more air exchange with the gasses in the tank, helping to promote the aerobic environment in the tank necessary to prevent odors from being created. It also lets you put a hose nozzle against it to backflush the vent line every time you pump out and/or wash the boat, preventing vent blockages. Better yet, increase the size of the vent line to 1". That would require installing another larger (1") vent fitting in the top, or at the top if necessary, of the tank...but that's an easy job, thanks to a li'l gizmo called the uniseal UNISEAL. In most cases, a larger diameter, shorter straighter vent line and open thru-hull accomplishes more than a second vent line--which, contrary to popular belief, is NOT my "ultimate" solution, it's just one possible solution that may or may not accomplish anything depending on shape of the hull and the locations of the thru-hulls.



--Peggie
 
Some progress today. I got the tank pumped out. I removed the sensor on the top and didn't have any problems with the tank being overfilled. It was about 2 inches from the top. With the sensor out I was able to pump out and flush the tank several times. Tomorrows task is cutting out more floor and getting to the vent line.

Oh, does the boat stink now !

The Brockerts
 
I’m surprised you have to cut the floor out to get to it. Ours was a 48’ Tustin built boat. All of the holding tank fittings were easily assessable through a hatch in the forward stateroom. Sorry to hear yours is not that way!
 
The hatch only exposed the sensor and part of the access plate. All the fittings( waste in, waste out and vent) will require cutting out the floor. Same for the starboard tank. Hatches are in the wrong place. They won't be when I'm done :)

The Brockerts
 
At least you are making some progress. Good luck.
 
Unless you had a spill while pumping out, that shouldn't cause the boat to stink, especially since you thoroughly rinsed out the tank. I'm concerned that it means the tank is leaking. Whether it already is or not, it will...all metal tanks do. The smartest thing you can do is replace it with a top quality plastic tank while you have access to it to do it. There's an excellent product called PureAyre PureAyre that'll eliminate all the residual odor from a spill or leak *when used as directed* (it's not a cleaning product...the area must be cleaned before using it).


I'd also check all the hoses for permeation...it's a simple test: wet clean rags in HOT water--as hot as you can handle. Wrap one around every section of hose (use a "new" clean rag for each one...don't re-use any). When the rags have cooled remove each and smell it. If you can smell anything on the rag, that hose has permeated. If you find that even one section has, you'd be wise to replace 'em all. As I've posted earlier, I'd have the entire system removed and re-installed by someone who knows what they're doing this time.



--Peggie
 
:thumb:
HeadMistress said:
Unless you had a spill while pumping out, that shouldn't cause the boat to stink, especially since you thoroughly rinsed out the tank. I'm concerned that it means the tank is leaking. Whether it already is or not, it will...all metal tanks do. The smartest thing you can do is replace it with a top quality plastic tank while you have access to it to do it. There's an excellent product called PureAyre PureAyre that'll eliminate all the residual odor from a spill or leak *when used as directed* (it's not a cleaning product...the area must be cleaned before using it).


I'd also check all the hoses for permeation...it's a simple test: wet clean rags in HOT water--as hot as you can handle. Wrap one around every section of hose (use a "new" clean rag for each one...don't re-use any). When the rags have cooled remove each and smell it. If you can smell anything on the rag, that hose has permeated. If you find that even one section has, you'd be wise to replace 'em all. As I've posted earlier, I'd have the entire system removed and re-installed by someone who knows what they're doing this time.



--Peggie
Click to expand...
 
Success on the vent clean out. Cut out the floor and found the vent inlet. Removed the vent line and had to use a drill with a 3/8 bit to drill out the vent inlet. It was solid for for the full 2 1/2 inches of its length.

Found some really confusing stuff and just for the record.

Vent lines in the first picture are for the main fuel tank and side tank. The vent line for the holding tank is next to the diesel fuel fill. So......

Vent lines next to the pump out lines are for fuel tanks vents.....
Vent line next to the fuel fill is for the the holding tank vents....

Now on to the vacuflush air leaks

The Brockerts
 
vents

Had difficulty establishing vents on my 48 Californian MY. Stb, has one holding tank vent and one water vent aft. Port aft has one fuel and one holding tank vent also aft. Nice to know which is which. Put water from hose directly into holding tank outside of boat, and you can hear which vent is active. I have two tanks, one vent port, one stb. Right beside the water vent STB and fuel port side.
 
For the first two years I owned my boat the heads would burp back after a flush. I found the vent plugged and the tank was half full of solids and could not be pumped out completely. I have three heads and only one 85 gal holding tank. Now when I do a pump out I can hear a loud suction sound as the tank empties. My first question is how was non of this not discovered in the survey. My 1986 Californian has a fiberglass built in place tank with full access to both ends. Joe, I feel for you and all you have been through.
 
After much work, I've been able to push water from outside the boat, thru the vent line into the holding tank. In this process I've found "SaniGard" vent filters buried in the bilges of the boat. They were not part of clogged vent. They probably have not been changed in years. The real question is are they worth the trouble and should I replace them? Also I want to be able to push water thru the vent line every time I pump out. Will this damage this filter?

The Brockerts
 

Attachments

  • Sanigard.JPG
    Sanigard.JPG
    93.2 KB · Views: 46
You will not be able to back flush with filters online and they will cause to tanks to smell. Remove them and keep the vents clear. If you get smell there are fixes you can do.
 
The Brockerts said:
After much work, I've been able to push water from outside the boat, thru the vent line into the holding tank. In this process I've found "SaniGard" vent filters buried in the bilges of the boat. They were not part of clogged vent. They probably have not been changed in years. The real question is are they worth the trouble and should I replace them? Also I want to be able to push water thru the vent line every time I pump out. Will this damage this filter?
Click to expand...


Contrarian opinion: We've not had issues with sanitation odors in the boat. We've not ever had any issues with vent filters. Mostly useful to keep from blasting marina neighbors off the dock when flushing. Change every 3-4 years or so, IIRC.

Can't backflush through the vent hose, though, with a filter in place.

-Chris
 
Never used a filter and never thought I needed one.

The biggest improvement I've found is by introducing O2 into the tank by mechanical or chemical means. I started with NoFlex and the light bulb went on. Later, I found an alternative that works just as well called sodium percarbonate.

You can buy a 5 lb bag on Amazon for $17. It's a real bargain compared to the name brand. I heard about it from a fellow TFer who posted it a while back. I've been using it for many months and have found similar results.

https://smile.amazon.com/Sodium-Per...=1580788177&sprefix=sodium+per,aps,215&sr=8-1
 
Folks - in my 1989 CPMY (California model) the only small breather outlets of the types described here in this thread, are the water and one for each of the diesel tanks.. i.e. i have three of them, with the two diesel ones in close proximity of the diesel filler caps.

Before I hunt down and try trace these is there any scenario where the holding tank may share the breather from say the diesel tank?
 
You must log in or register to reply here.

Similar threads

M
Dip-Tube Question
Replies
4
Views
470
HeadMistress
HeadMistress
G
1987 Californian 42MY Blige Pumps
Replies
3
Views
554
Gneissman61
G
R
Holding tank vent smell and aeration
2 3
Replies
75
Views
6K
Comodave
Comodave
Mac2
Hydraulic steering mystery
Replies
19
Views
2K
Mac2
Mac2
PhilPB
Holding Tank Vent Configuration
Replies
22
Views
3K
Bacchus
Bacchus

Latest posts

Back
Top Bottom