Well, not really.
But when we filled the water tanks after getting the pink stuff out the two tanks in the aft cabin blew up big time. The wood covers over them were bulging up about 3-4 inches in the middle. I pulled the wood off and the tanks were all blowed up real good, looked like a lot of trapped air in them. We pumped a few gallons of water out of them and then went down.
I had a quick look for a vent, didn't see one on the sides so it must be on the transom and I suspect the tanks are sharing a vent that is plugged, with getting the mast up and the rig tensioned and then getting the sails on we just ran out of time.
Anyone know for sure where the vent is for these two tanks? I'm thinking about running a fish tape through from the tank out to see what happens.
Bud:
I am not sure where your vent location is for your year of boat, but I know on our 1990 tank vents there is a little screen on the vent. I have cleaned spiders nest out of the screens in the past. Just a fyi.
Randy
Randy Sherwood
Mutualfun 1990 # 1057
T/R W/K M35a
Home. Charlotte, Mi.
Boat. St Augustine,Fl.
On my boat the water vent is on the starboard side between the aft locker and the seat.
Bill Matley
Duncan Bay Boat Club
Cheboygan, Michigan
Lakes Huron, Michigan,
Canadian North Channel
"Spirit of Aloha" Hull #1252
Bud,
On my 1996 MKII the aft water tank vents (2) are on the transom swim step, just inboard of the of the shore power connectors on the stbd side. The single vent on the port side is for the fuel. The tank under the V Berth is vented into the anchor locker and located in the upper port side of the locker.
Sorry for the bad pic but you should be able to see where they are.
Jack
Solstice
Hull #1598
1996 MKII/TR/FK - M35AC - 3 Blade MaxProp
Lake Texoma
www.texomasailing.org
Thanks guys. I went through my pictures of the boat and found one of the transom from when it was hauled for survey and it doesn't appear to have two vents like Jack's boat. I guess I will just have to do a thorough inspection next time I go down to the boat. Funny I buffed and waxed the whole hull and don't recall seeing them anywhere so I'm suspecting they are above the rub rail, and area that I haven't got to yet. It's a bummer when your boat is a 2 hour drive from home.
I've had my aft centerline tank bulge enough to pop the plywood cover off, pulling the screws out. Yet the tank vent is NOT clogged, I watch it while filling and it gurgles until it is full, then blows water. So I don't understand why it bulges so much; the pressure should vent, but doesn't seem to. I clean the vent screens with an old toothbrush.
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
So I was down to the boat today and I traced the vent, it comes out on the transom on the stbd side of the boarding ladder, the fuel one is on the right. It appears both water stern tanks share a vent. The vent was loose and needed to come out and be re-bedded so after a minor war involving sharp tools I got the hose off and the vent out. The vent was not clogged. So I blew down the hose and I could hear the water gurgling in the tanks. So I am totally mystified as to what is going on here. When I read Gary's reply above I thought that wasn't possible, but it totally is.
I think we will just have to put water in very slowly so as not to force any air into the tanks because the vents just don't seem to work.
The bulging of the plastic water tanks isn't due to captured air...it is merely the weight of the water deforming the tank slightly. There is no harm caused by this (unless popping the plywood covers up counts as harm).
The following procedure may sound weird, but this is what I do: My water tank plywood aft covers are not screwed down; they just simply set in place. When I fill the water tanks to overflowing, the two aft tanks will be bulged slightly on top. Following the fill, I go below and lift up the mattress so I can view the raised covers. I select one of the tanks at the manifold, open the cold water tap, and run water until its cover sets down squarely in place. This is usually only about 2 minutes of running water. Then I select the other tank and run water until its cover sets into position.
Easy problem; easy solution. Important to note, however, is that if you haven't sealed the tank inspection ports they will leak during the bulge and may cause you to wonder why you have water in the bilge. About 5 years ago I sealed all of my water tank inspection port threads with a small bead of 3M 5200, and they haven't leaked since. Using 5200 on this plastic composition does not make a permanent unbreakable seal; it will still be easy to 'crack' the seal to open the ports if and when you ever need access to the tank interior.
Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
Larry, thanks for the info, that was how we "solved" the problem just bled off a bit of water. But if that's just the weight of water doing that Catalina must have cheaped down on the tanks, on our '90 28 the tanks definitely did not do that, even when full to the very top. On that boat the 2nd tank (20 gal.) was under the starboard cabin settee and shared space with a locker so we saw that tank a lot. Never did it bulge. Shudder to think that the holding tank is going to do that as well?
[QUOTE=bstreet;5346]...Shudder to think that the holding tank is going to do that as well?...[/QUOTE]
I can attest that if someone is sitting on the settee over the holding tank, and you try to pump more fluid into a full tank, the tank bulges and will lift a person up a fraction of an inch in time with the pump strokes.
Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/
Holy crap! (lousy pun intended)
[QUOTE=deising;5347]I can attest that if someone is sitting on the settee over the holding tank, and you try to pump more fluid into a full tank, the tank bulges and will lift a person up a fraction of an inch in time with the pump strokes.[/QUOTE]
That should not happen unless your holding tank vent is plugged.
How do I know this? Last week we were sailing along and my wife was pumping the head, water and TP started squirting out of the vent (in the stanchion) at an alarming rate!
Jason V
Vancouver, BC, Canada
I thought about that, Jason, and here is my conclusion:
A column of water 12 inches high exerts a pressure of 0.43 psi at its base. If you had the vent hose filled with liquid (and assuming the density of water alone), there could be nearly 1.2 psi of pressure acting upward on the tank top. Multiply that pressure times an area 12x20 inches (just a guesstimate) and you have a force of 288 lbs.
Theoretically, once the liquid exits the vent, the pressure cannot go higher. If the vent was completely clogged the pressure could go even higher than 1.2 psi.
Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/
Duane, I have always wondered about what psi there would be in that area of our boats... ;)
Glenn Druhot
Carpe Diem
New Bern, NC
35* 6' 10" N / 77* 2' 30" W
2001 C36, Hull #1965
Std Rig; Wing Keel; M35B
Duane, I buy your calculations of head presure on the water tanks, not to be confused with the also discussed HEAD pressure on the holding tank.
I would agree with your colomn of water calculation but, it does not take into account the water pressure of the hose used to fill the tank, standard faucet pressure is 30 to 50 PSI. I have a hose with a high pressure nozzle on it that fits fairly snugly in my fill port. Once my tanks are full I get a small gyser of water coming out the fill port when I remove the hose. When the tanks are full and water is coming out the vent you get a pressure build up. The vent can easily vent the air from the tanks but when the vent line fills with water the pressure can build to near the discharge pressure of the hose as the vent line is much smaller than the fill line. See the scientific formula below.
Gosinta pressure minus gosouta pressure due to restriced flow = pressure per square inch x area of tank in square inches.
Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas
Absolutely correct, Steve.
You are talking about a dynamic condition where you are pushing water into a volume faster than it can escape, so indeed the pressure can build up. If you fill the volume slowly, and the vent is clear, the only pressure you should experience is the static head pressure from the height of the fluid column.
But you know this...
Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/
Just to add to the mystery....
Last weekend I filled my forward water tank, which had gone empty the prior week, just [I]BEFORE[/I] I lathered up in the shower (it's usually just [I]AFTER[/I] :mad:). When unscrewing the filler cap, there is an audible hiss as the pressure equalizes. However, the vent is not blocked, as I watched it gurgle and eventually spit water as I filled the tank. The vent is in the anchor locker.
This makes even less sense to me than the big bulge I noted in the aft centerline tank, though the technical explanations in the last couple posts certainly explain that pretty well. I'm starting to think that the hiss I hear on removing the filler cap is the tank breathing a sigh of relief at being filled :p
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
I just got an email that someone (to remain nameless) posted a reply to this thread and when I went to check it, it was not there. Strange.
Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/
[QUOTE=plaineolde;5377]Just to add to the mystery....
Last weekend I filled my forward water tank, which had gone empty the prior week, just [I]BEFORE[/I] I lathered up in the shower (it's usually just [I]AFTER[/I] :mad:). When unscrewing the filler cap, there is an audible hiss as the pressure equalizes. However, the vent is not blocked, as I watched it gurgle and eventually spit water as I filled the tank. The vent is in the anchor locker.
This makes even less sense to me than the big bulge I noted in the aft centerline tank, though the technical explanations in the last couple posts certainly explain that pretty well. I'm starting to think that the hiss I hear on removing the filler cap is the tank breathing a sigh of relief at being filled :p[/QUOTE]
Gary,
If there is a hiss when you open the filler cap, then the vent MUST be clogged. There is no other possibility. Check for a loop or low spot trapping water.
Gene Foraker
Sandusky Yacht Club
Sandusky, OH
1999 C36 #1786
Gypsy Wagon
This past weekend when we got to the boat I checked the bow area again and it was dry and the overflow for that tank also is clear. But it is seems it was the inspection cap leaking as was suggested. So I sealed it with 5200 and hopefully that will solve that leak.
Just to update this, on the weekend I filled all the water tanks with the hose set to run extremely slowly, so that air could vent out the filler hose as well as the vent. Took about 20 mins per aft tank so around a gallon per minute. When I filled both aft tanks I could hear gurgling through the vent on the transom and when each tank was full water came out the vent. Then I checked the tanks and they were both blowed up real good. So it is not a venting problem.
Then did the same dance with the bow tank, removed the hose when it was full, went below to check the tank and found it did the same blowed up thing as the aft tanks did. I pulled the vent line off it to check it for clear (it was) and water blew out the vent connection with pretty good force, hard enough to spray a stream of water right over to the side of the hull (vent points forward/starboard). At that time the hose was shut off and removed. So just the weight of water in a full tank does indeed exert a pretty good force on the tank. The force is also enough to make the 5200 sealed inspection port leak which it is now doing again.
This exercise had the side benefit of proving that my new limber hole works as all the water spewing from the bow tank dutifully found its way to the bilge. These tanks must be thinner than older ones though since our 1990 28 never did that with either the bow or side tank.
Bud, on sealing the access ports with 5200, maybe I didn't describe my successful use of 5200 in full.
I placed a thin bead of 5200 - say about 1/8 inch dia - midway on the threads of the access cap. Then I tightened the cap by hand. Then I waited a week or so for the 5200 to set before I again filled the tank to over-full.
It's a fussy process but it has proved successful for me for, maybe, 5 years now.
Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
That's pretty much what I did Larry, had a full week between putting on the 5200 and refilling the tank. I was surprised to see beads of water bleeding out around and through the 5200. I might try that again only maybe I'll use a more elastic sealant, like Sikaflex 291 or even 3M 101. All 3 of the tanks are leaking, on one of them someone tried hot glue which didn't work and made a mess to clean up. I made my handy-dandy little drip catcher for the stuffing box to direct water to the bilge so it's dry back there, now everytime I fill the aft tanks I have a quart or two of water under the engine.
I was really surprised that the inspection port has nothing to bottom out against, you can screw it right through and it will fall into the tank. That is just a really odd setup and none too useful either. There's guys around that can "weld" those tanks to repair them, I'm going to hunt one of them down and see what ideas might come out of that.