How much vacuum does it take

[Peggie Hall HeadMistress]

Peggy,I pulled the hose off the vent.I also opened up the inspection port to make sure there would be adequate air supply.

That's the third time you've said you pulled it off...so I'm guessing that means the answer to my question is, no...you haven't reconnected it to the tank.

I am beginning to wonder if there is an airleak in a section of the hose leading up to the deck.

If there is, you should hear the hiss of air being pulled through the leak when suction is applied or being pushed out of the leak when air is forced down the hose.

 

[Guest]

Pump out problems

Peggie raises an interesting point. When we took possession of our boat the holding tank was plugged at the vent through hull scupper. Some time after clearing that problem it became plugged at the bronze elbow where the vent line connects to the tank. I used a wire coat hanger to auger the elbow of encrusted goo. That was in 2002. The system remains trouble free after many extended cruises. Have patience and let us know the cause once you find it.

Terry Cox

 

[paiscool]

Actually is is reattached

I did reattach it.But the other point I want to make is I took the cover off the inspection port to make sure it had plenty of air.So correct me if I am wrong here and correct my logic:
The hose to the deck fitting is submerged under the liquid.I open the inspection port cover so in essence the tank has an unlimited access to air.I begin to suck the contents of the tank from the deck fittting,ordianrily the liquid is sucked up but in my case nothing comes out.Because the suction should have the liquid barrier to keep from sucking air,there should be a vacuum that is generated and as the liquid is sucked up in a normal situation,the air replaces the space that the liquid took up.Until the liquid is at a point at which air is being sucked up the pipe and the vacuum is gone.
Forget the vent tube,the vent filter,whatever.I have allowed an unfettered amount of air to replace the liquid that should be sucked.
What am I missing in the Physics of this process? And I mean this in only a good way.
BTW tahnks everyone for your patience.

 

[Ron20324]

close up the tank and blow into the deck fitting with a shop vac. see if that clears the hose and/or air blows out the vent?

 

[petersea]

Forget the vent tube,the vent filter,whatever.I have allowed an unfettered amount of air to replace the liquid that should be sucked.
What am I missing in the Physics of this process? And I mean this in only a good way.
BTW tahnks everyone for your patience.

Yes you are correct with the inspection port open you have "vented" the tank.

Since you have determined the hose from the deck plate to the tank is clear the only other thing is the actual pick up tube in the tank. If that is clear I suspect that some where there is a vacuum leak causing you problems. Remember that just cuz the hose is clear does not mean it is air tight and will keep a "vacuum". At this point I might replace the hose from the deck plate to the tank after verifying the tank pick up is not the problem. Your shop vac may "overpower" a small air leak when using it to blow the lines clear but may not be overpower that same leak on the suction side to create a vacuum. Not to be condescending but what about the fitting at the pump out fitting ? is it a "universal type" or a threaded screw type ? Vacuum can also be lost there as well I use a o ring on the threaded side just for that reason. Good Luck !

 

[paiscool]

I dont think mine has a pickup tube unless this is something I am missing.It is a 1995 320 Catalina with a Ronco tank.There is a Lower Hose that exits the tank at the bottom and goes up to the deck.The upper hose goes back to the head.
The pumpout has a "universal" fitting that is rubber and fits many outlets.But neither a shop vac or the pumpout works and when I tried the shop vac you could hear the vacuum generated even though nothing came out.
Thanks

 

[petersea]

I dont think mine has a pickup tube unless this is something I am missing.It is a 1995 320 Catalina with a Ronco tank.There is a Lower Hose that exits the tank at the bottom and goes up to the deck.The upper hose goes back to the head.
The pumpout has a "universal" fitting that is rubber and fits many outlets.But neither a shop vac or the pumpout works and when I tried the shop vac you could hear the vacuum generated even though nothing came out.
Thanks

Ok here is my suggestion....... I assumed most newer (a 1995 would be newer in my book) boats would use a pick up type discharge but since you have a bottom draw it changes things a little. Since you are sure the line is clear there must be a vacuum leak some where. You are going to need to do some system diagnostics. Try cutting the discharge hose in half several feet away from the tank (you can reconnect with a barb to barb fitting later if needed)and see if you can pump out (water) with the shop vac. Make some sort of fitting so it is as air tight as possible. Does it pump out ?? If so you have at least determined that the problems is somewhere between the deck plate and where you cut the hose.
If you can pump put the tank next try pumping out from the deck plate using a five gallon bucket with the hose end inside the bucket. You will have at least determined what side of the system has a problem.
If you could not pump out the tank then you have at least determined the problem is from where you cut hose to the tank (maybe the tank fitting). While cutting the hose is not the best plan I'm not sure what else to tell you except that I would replace the hose anyway when you get the system working correctly if for no other reason it is 15 years old and if it is a bottom discharge tank the hose would have had "black" water sitting in it and is due for replacement anyway. Make sure to make all you test connections as leak free as possible maybe even having to duck tape the shop vac hose to your boat hoses.
I have never been a big fan of those "universal" fitting on the pump out station hoses and prefer the threaded connections but if that is what they have you are stuck using it so just make sure the fitting is as tight as possible and has no vacuum leaks.
I can't help but notice that this has been a issue for you for quite a while now and I can guess very frustrating to you . I am intrigued now because it is been so difficult to determine what is wrong.
Keep us updated ! ! Good Luck !

 

[petersea]

paiscool,

Another thought came to mind. Is there a overboard discharge macerate on this system and if so how is it plumbed ??

If you decide to do any of the system diagnostic above you may want to keep the inspection port open just to know that there is plenty of "vent" and it eliminates the tank vent issue. You can then confirm a working pump out test retesting with the vent attached and inspection port closed.

 

[Lee Coller]

Reading through all these responses, it appears that:

1) You've only tried a single pump-out station.
2) You don't know if its worked for anyone else.

Pump-out stations are notorious for not working very well or being out of order. My guess is its your pump-out station that's not working and your boat is fine.

 

[c_witch]

Pressure check the pump out line. Disconnect it from the tank and install a plug. A simple 1 1/2'' inch wooden plug should be fine. Disconnect at the deck fitting and make a plug WITH and tire valve stem installed in it. Install this and clamp it as well. Now simply pump up the hose with 20lbs pressure wait a few minutes and then measure the air pressure and see if there is any bleed down. Hopefully there won't be and if not then the hose is fine. Make sure to blow out the vent line and make sure that the fitting is also clear of obstruction. BTW on barbed fitting I will usually use a bit of silicone caulking to make sure of a complete seal. Hope this may help. If the lines are ok then I'd assume its not your boat.

 

[petersea]

paiscool,

Verifying the pump out station was first on the check list, did you do this ?? I thought you had established other boats had used the pump out in question. If need be check the pump out by simple putting the hose end in a bucket or for that matter in the water. Let us know results

 

[Guest]

Pump out woes

Just did a check upon my return from a frosty cruise this week to Skull Island at the bottom of West Sound. The La Conner marina meter read 0.4 when the pump was extracting stuff from our tank.

First time sailing in a blizzard. Sub freezing temps. Furnace kept the inside of the boat warm, though.

Terry Cox

 

[gettinthere]

It could be a poor vacuum seal in the output hose from your tank to your deck fitting. Did you check the hose clamps on the hose to deck fitting connection?
It could also be a poor seal at the pumpout to deck fitting. I've had some pumpout operators run a water hose over the deck fitting to create an airtight seal.

You sucked up your holding tank contents with your wet/dry vac??? YUCCK!

 

[paiscool]

Just got back from vacation.Thanks everyone for your ideas and responses.I am at the point where I am going to think it would be a vacuum leak.I am ordering hose over the next 2 weeks and when I get back from my next business trip,I will replace the discharge hose.I may as well because if I have to take off the deck plate,I may as well get this done.I will let everyone know when I find the solution.

 

[paiscool]

The answer to the problem!!!!!

Well,it goes to show that if you talk to people you get answers.Let me preface this by saying,I travel all the time for my job and rarely am home so catching my fellow owners is difficult.That being said the answer to my problem has been the pumpout station!
What I found out is that everyone who uses it has to open the valve before they turn it on,then put a water hose in the hose and fill it with water,then close the valve and turn it on,put the pumpout hose over the deckfill,then open the valve to suck.They say that this is how they prime it and it doesnt work unless they do.Now they tell me!!!!
So everything I went through was for naught.Thanks to everyone for their help.I know more than I ever wanted to know about a pumpout.

 

[Guest]

Problem solved

Glad to hear that you found the solution before expending too much time and money chasing dead ends. I hate those dead ends.

As I mentioned in an earlier post I usually dip the pump out nozzle into the water as a test to make sure that it is in fact working before placing it into the boat's pump out fitting. Our local system seems at times to take forever to build suction for whatever reason.

Terry Cox