Plumbing to/from holding tank on 1977 C25

[Jim Marron]

I've owned my C25 for 3 years and, after first pump-out, never really bothered with the head/holding tank (day sails and over night docking w/ facilities). One of this year's projects is replacing the head and putting it in service. When tracking the existing hoses, I was amazed to find the 3/4 inch "clean" water intake came FROM the holding tank. Not surprizing, the large hose goes to the holding tank. All this looks like original Catalina work. Thru-hulls exist in the vacinity of the tank but look like they have never been used.Question 1a&b: Can this be right? Am I missing something?Question 2a&b: If this is correct, how do you manage it? Start with holding tank 3/4 full of clean water and chemical, then pump out when full?

 

[Peggie Hall/HeadMistress]

No...it's definitely not right!

That has to be a POs dumb idea...'cuz it's certainly NOT the way Catalina plumbed it! Are you sure you haven't confused the tank vent hose with the head intake hose (but if it's connected to the toilet, that WOULD be hard to do!). The only other possibility that would make any sense is that you actually have two tanks--one for flush water (a POs idea of how to avoid flushing with sea water) and a holding tank. But again, if the toilet discharge and the head intake are connected to the same tank, it would rule that out.The head intake (3/4" ID hose) SHOULD be connected to a below-waterline thru-hull/seacock...the head discharge (1.5" ID hose) should go to the tank entering it at the top...pumpout hose (also 1.5" ID) usually comes out of tank at the bottom, but may be on the top with a tube inside the tank to the bottom. Any other 1.5" thru-hulls would be used to flush the toilet directly overboard and/or dump the tank, but since you must be at least 3 miles offshore (in open ocean, not just 3 miles from the nearest shore in LIS) to do either one legally, there prob'ly won't be hoses connected to them.Can you wait about 3 weeks to start this project? If so, my new book (link below) provides complete instructions for installing a toilet and holding tank.

 

[Don Tonks]

Plumbing

Hi, All the systems I have seen have always taken raw water into the head and sent the output to the tank (top port). There is usually a Y valve on the output of the tank (bottom port) sending the effluent to either the pumpout deck fitting or the overboard through-hull. There is sometimes a macerator pump between the Y valve and the through-hull. Do not put this between the tank and the Y valve or you will have problems when trying to pump out through the deck fitting. There should also be a small (3/8") line connected to the top of the tank as a vent. The other end is connected to a fitting near the pump-out deck plate and looks like a button. This needs to be clear or you might damage the tank while filling or emptying. It sounds like someone that owned the boat previously heard the toilet could not connect to the seacock ( output ) or the cock had to be fastened and disconnected the raw water intake.Hope this helps,Don

 

[Jim Marron]

Thanks for the help....

Don & Peggy,Thanks very much for you replies. I don't know why it was plumbed this way, nor what the previous owner was thinking when he did it (excellent sailor and original owner of this boat). I removed the thru-hull cap (small one) and will connect the intake to this.I'm a little concerned about all this happening below the water line, so I'll install a shut-off valve and wait for your book, Peggy.Thanks again,Jim