Can't Pump Holding Tank

[drpaoletta]

I'm hoping more seasoned sailboat owners can help me with this problem. I'm having issues pumping the sanitary tank (Catalina-30, 1983) from the deck fitting with vacuum equipment available at CA docks. I can pump the tank overboard using the macerator pump, the discharge line does not have a selector valve (deck/overboard) and I am able to add water to the tank through the deck fitting. The vacuum hose seals well to the deck fitting and appears to pull a vacuum on the discharge hoses, but the tank level doesn't go down!
I'm stumped.

[peghall]

Originally Posted by drpaoletta

I'm hoping more seasoned sailboat owners can help me with this problem. I'm having issues pumping the sanitary tank (Catalina-30, 1983) from the deck fitting with vacuum equipment available at CA docks. I can pump the tank overboard using the macerator pump, the discharge line does not have a selector valve (deck/overboard) and I am able to add water to the tank through the deck fitting. The vacuum hose seals well to the deck fitting and appears to pull a vacuum on the discharge hoses, but the tank level doesn't go down!
I'm stumped.

Your tank vent is blocked, causing the pumpout to pull a vacuum that prevents anything from being pulled out of the tank. It's a common problem on Catalinas because Catalina doesn't (or didn't when your boat was built) run the vent to a thru-hull, they run it into a rail stanchion that has only a few very small holes on the aft side of it...and even dust and pollen can plug up those holes. If you're lucky, a previous owner has corrected that by rerouting the vent line into a thru-hull.

Whatever the situation with the vent, it's blocked. The most common locations for vent line blockages on a sailboat are the previously discussed vent thru-hull and the connection to the tank--both the tank vent fitting and that end of the vent line. Clean all of it out using a screwdriver blade, ice pick or whatever works and you should be able to pump out.

[Cowboy Sailer]

The previous owner had attached the hoses on the top of my holding tank backwards. That is, the output of the toilet went to a fitting with a dip tube down to the bottom and the deck fitting hose went to w fitting that did NOT have a dip tube. Instead of switching the hoses I added a dip tube to the fitting from the deck fitting. This solved the problem.
It also allowed me to siphon the holding tank out while at sea. That is a whole 'nuther project.
I used a wet/dry vacuum wand extension for the dip tube pvc, glued it into the fitting and cut the bottom at a 45 degree angle. Good luck

[drpaoletta]

Originally Posted by peghall

Your tank vent is blocked, causing the pumpout to pull a vacuum that prevents anything from being pulled out of the tank. It's a common problem on Catalinas because Catalina doesn't (or didn't when your boat was built) run the vent to a thru-hull, they run it into a rail stanchion that has only a few very small holes on the aft side of it...and even dust and pollen can plug up those holes. If you're lucky, a previous owner has corrected that by rerouting the vent line into a thru-hull.

Whatever the situation with the vent, it's blocked. The most common locations for vent line blockages on a sailboat are the previously discussed vent thru-hull and the connection to the tank--both the tank vent fitting and that end of the vent line. Clean all of it out using a screwdriver blade, ice pick or whatever works and you should be able to pump out.

Peghall,
Thanks for your reply. However during my pump out attempt yesterday I disconnected the tank vent hose and removed the elbow fitting so I could look into the tank. I was still unable to suck the contents out from on deck. Could there be debris in the tank acting like a one-way valve?

[sailorboy1]

Check your valve/hose line up, on my last boat if you had the discharge lined up go overboard you could not deck pumpout. Follow the deck line down to the tank to see if there is a valve in it.

Your deck pump out line could be clogged also, Have you tried to flush water down it to see if it flows?

[jaybird1111]

are you absolutely sure the pumpout pump is working? Don't laugh - it happens. Drop it in the water and see if it draws b/f trying it on your tank

[drpaoletta]

Yes, they have a barrel of flush water and a clear window in the pump out hose. I wish things were that easy!

[jldunn86]

Originally Posted by drpaoletta

Peghall,
Thanks for your reply. However during my pump out attempt yesterday I disconnected the tank vent hose and removed the elbow fitting so I could look into the tank. I was still unable to suck the contents out from on deck. Could there be debris in the tank acting like a one-way valve?

Regards debris in tank: Not sure if yours an integral hull/tank or stand alone poly tank. I have had experience with the coating of an integral tank turning loose in chips of 2-3" size, which then slipped down to the low point in the tank where deck suction and maserator line attached. They made the prefect flapper check valve. You could flush through it but get little to nothing out. The maserator would pump then lose suction as if the tank was empty. The tank lid finely lifted, which was under the captain's bunk. He was not a happy Captain as we had just made USVI, and his bunk, bilge etc was a mess.
Good luck.

[sailorboy1]

Originally Posted by drpaoletta

Yes, they have a barrel of flush water and a clear window in the pump out hose. I wish things were that easy!

So you can pour water down the line? If so are you sure that the deck line connects to the bottom of the tank?

[drpaoletta]

Yes, I can flush water into the tank from the deck fitting...

[CampDavid]

Run a fish tape down from the deck fitting and into the tank. That should tell you if the clog is in fact clogged. If the vent line is clogged it should drain the toilet
bowl.


Sent from my SGH-I337M using Cruisers Sailing Forum mobile app

[Cadence]

This may sound dumb. It sounds as though you have covered all the bases. Is it possible you have a small air leak in deck pump out line.

[rwidman]

Originally Posted by CampDavid

Run a fish tape down from the deck fitting and into the tank. That should tell you if the clog is in fact clogged. If the vent line is clogged it should drain the toilet
bowl.


Sent from my SGH-I337M using Cruisers Sailing Forum mobile app

If the OP can add water to the tank through the pumpout fitting, the hose is not blocked.

We can speculate all we want to and this will not fix his situation. The only way to find the problem is to actually dig into the system and see what is causing the problem.

[rwidman]

Originally Posted by Cadence

This may sound dumb. It sounds as though you have covered all the bases. Is it possible you have a small air leak in deck pump out line.

No, not dumb. The OP should be able to tell if the pumpout is sucking air (as it would with a leak you describe) or sucking against a blockage.

[davido]

IF the hose from the deck fitting to the tank goes to the bottom of the tank (without a valve as you stated), then the problem could be one of four things.

1. You have inadequate suction with the pump-out system.

2. There is a leak in the hose that allows the suction to escape thereby not pulling black water from the tank.

3. The hose between the deck fitting and the tank bottom has failed internally allowing the inner lining of the hose to collapse under suction and thereby not pulling the black water from the tank. (Allows you to pour water into tank, but not suck water from the tank)

4. There is a blockage within the tank.

If the suction hose is not coming from the bottom of the tank or if there is a valve between deck and tank, then the above does not fully apply to your problem.

Let the group know.