Odd behavior during pump-out

May 7, 2011
189
Catalina 30 Lake Lanier
Our 1985 Catalina 30 has an electric macerating head that pumps directly into the OEM holding tank. Do direct discharge, no macerator pump overboard. (We sail on a fresh water reservoir and black water discharge is NOT allowed and by law must be made impossible.) All hoses were replaced except the hose to the pump-out fitting 3 years ago.

Up to now the pump outs have been as you would expect. Our marina's pump out station experienced issues holding a vacuum recently and had to be repaired. Now when I go there, it does not seem to empty the tank. I pumped out one day and the next afternoon the tank overflowed. Yesterday I pumped out twice, and each time the flow seemed to stop after several minutes. (Pump still running but I could see particulates floating in the effluent not going up or down.) I had checked the vent, it seems clear and I could hear the air being drawn in. I closed the fitting, took it off, hooked it back and nothing came up. I usually get at least a small splash. The second time I used the dock hose to put in several gallons of fresh water. I stood on the gunwale a few time to shake the contents. When I ran the pump again only clear water came up for a minute, then suddenly back to the usual effluent until it again eventually just stopped as before.

I asked the marina personnel about it, they say no one else has reported any issues since the pump was fixed.

Just to be sure, I'm going to replace the 10' vent hose. Is there anything else that may cause such odd behavior?
 

HMT2

.
Mar 20, 2014
885
Hunter 31 828 Shoreacres, TX
Peggie is THE authority on this, but sounds like a clogged vent to me.
 
Dec 2, 1997
8,177
- - LIttle Rock
Sounded like a blocked tank vent to me too...until I reread your post. I'm now wondering if you have a blocked pumpout fitting...how did you add water to the tank? If via the pumpout fitting, it seems that the pumpout only pulled out the water in the pumpout line.

And btw, a 10' vent line is waaay too long...where does it exit the boat--thru-hull or slit in a rail stanchion?

there is the possibility that your marina's pumpout still may not be working, so it would be worth the time and effort to try pumping out at another marina.

But whether you problem is a blocked vent or a blocked pumpout line, you do need a tank level indicator to know how much is in the tank, before AND after pumpout. SCAD is top rated and easy to install because the sender goes on the outside of the tank ...you'll need the SOLO single tank version. Scad Tank Monitors

And you might want to check out the link in my signature....the title (my publisher's idea) is a bit misleading...'cuz although it does deal with every source of odor on a boat and how to cure, or better yet PREVENT 'em, it's actually a comprehensive "marine toilets and sanitation systems 101" manual that explains the laws, describes all the types of systems and how they work, and will help you learn how to operate and maintain your system to prevent 99% of problems instead of having to cure 'em. 'Cuz you get to do any preventive maintenance on your terms when it's convenient...the need to cure a problem never happens when it is! And I'm always glad to answer any questions it doesn't.

--Peggie
 
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Apr 5, 2009
1,655
Catalina '88 C30 tr/bs Oak Harbor, WA
I have had that problem on my C30 but was able to see what was happening because I have a cleanout port in the top of the tank. My tank builds up a shale like substance on the inside of the tank and it brakes off and covers the outlet. I can run water down the pump-out hose and it will push it out of the way but when I tried to pump, it would flip up and cover the outlet again. It was a naturally occurring one-way check value. I ended up using a hose through the clean out and a stiff rod to breakup and blast the shale away from the outlet while pumping and got the contents to a reasonably clean state. I then needed reach into the tank and remove the shale by hand. Not fun!
 
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Johnb

.
Jan 22, 2008
1,302
Hunter 37-cutter Richmond CA
Dip the end of the pump out hose in the lake and if it sucks heartily the problem is in the boat.
 
Apr 5, 2009
1,655
Catalina '88 C30 tr/bs Oak Harbor, WA
Since you are in fresh water you can use this chemical TankTechsRx – Totally Green, Totally Clean! which breaks down Struvite shale. (read about it in the FAQ.) I use it in my motorhome and it works very well. I tried it in my C30 but it did not work. I talked with Peggy and she indicated that the process is impeded by salt water so now I am using Noflex Digestor from Zaal and it seams to be controlling the problem. Zaal NOFLEX | Fisheries Supply
 
May 7, 2011
189
Catalina 30 Lake Lanier
And btw, a 10' vent line is waaay too long...where does it exit the boat--thru-hull or slit in a rail stanchion?
It is vented via a 3/8" hole at the base of a rail stanchion about a third of the way o the bow, just outside and facing the head window. The tank is about a third of the way aft under a settee. (About 5' from center of tank to center of stanchion.) The vent line was going perpendicular to the centerline to the hull, then up a foot or so, then forward, then up again to the stanchion base. I ran new 1" vent line going forward at an angle to the hull and up, then a 45 degree straight up to the stanchion base. It is now only about 7'. I was able to get a 1" elbow into the tank, but the base is still 5/8. I drilled out the vent hole to a 1/2"

When I filled the tank with the hose, it was down the pump-out hose with a few jets at the vent to try to make sure it was clear.

Thanks for the info on the tank monitor, guessing is not always reliable and having the vent overflow all over the deck is a mess.
 
Dec 2, 1997
8,177
- - LIttle Rock
You improved the venting but not nearly enough to prevent problems...we need to get it out of the stanchion and onto a 1" open thru-hull and a 1" tank fitting, and also straighten it out. It's a lot easier to do than you may think it is, and actually inexpensive. If you want to do it, send me a PM that includes your email address so we can move the conversation to an easier method than PMs.

--Peggie
 

Kopite

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Mar 11, 2015
107
Catalina 27 Monroe MI
As I only pump out once a year, I disconnect the vent pipe at the tank and get much improved suction.
 
Jul 27, 2017
44
Catalina 30 5167 Texas
If you decide to replace the stanchion vent, there is an excellent thread located here:


When I did mine I uploaded lots of pictures and information. Peggy was, and always is, a tremendous help.
 
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