[C320-list] Re Replumbing head for direct discharge

[Graeme Clark]

Subject: [C320-list] Replumbing head for direct discharge.
To: "C320-List at Catalina320.com" <C320-List at Catalina320.com>
Date: Thursday, October 17, 2013, 8:41 AM

I am replacing a defunct macerator,
and it seems this is a good time to replumb for direct
discharge as well. Any info/photos would be most
appreciated.
Thanks,
Lou Spitz
Merry Chase # 195

Hopefully I can provide some useful advice here as our boat (1996, #303) was delivered with the direct discharge option fitted.

As previously posted, there is a Y-valve by the holding tank just above the macerator pump fixed to  a wooden block bonded to the inside of the hull.

We have had no end of problems with this valve furring up with calcium type deposits (i.e. hard crystalline, not waste matter!)

In the end it was so nearly seized and so stiff to turn that the handle (polyethylene) tore off and for a while we were only able to turn the valve by the use of a pair of pliers until the small lug of plastic also tore off!

Replacing the valve was a nightmare because it is fitted with 'barbed' outlets so getting the old hose off was not easy. Now only a year later we are in a similar position

Anyway this got me to thinking how come something that was only ever temporarily immersed, furred up so quickly and then it dawned on me that it isn't temporarily immersed its nearly permanently immersed because  the  "Y" valve is exactly that- Y-shaped. The top right arm of the Y is the inlet from the toilet, the bottom arm of the Y goes to the holding tank and the top left arm of the Y goes to the overboard discharge.  Thus any residual water in the pipes will flow back and sit in the valve where it precipitates ad calcifies.

If you leave the  valve set to the holding tank this isn't a problem as any residual fluid will flow into the tank.

A better solution would mean thinking carefully about the choice and where to locate the valve and the routing of pipes to and from it so that residual fluid doesn't collect there.  Unlike many boats the Cat320 doesn't seem to have any anti siphon valve fitted in the toilet system (no doubt because originally there was no overboard outlet) but it might not be a bad idea to fit one once you have a direct discharge overboard.

One final point - our overboard discharge valve was fitted under the very forward end of the starboard saloon seat (under the little square 'hatch). I am guessing this was to avoid weakening the hull too much in one place where the macerator outlet is? Anyway it requires quite a run of piping (behind the batteries) and if you work it out it takes around 30  up/down pump cycles to get the waste out of the pipe. If you do less than that you risk a blockage for obvious reasons.

I am ashamed to report that the rules for overboard discharge are much more relaxed here in Britain although I daresay that will change quite soon. Holding tanks over here are the exception rather than the rule although modern boats have them fitted I think.  We are pleased to have both options - or we will be when we get a decent valve sorted out

The Y valve we had - not recommended s two have now failed - was like this $(KGrHqF,!i8FEHcrGTlMBROQvi4kCQ~~60_1.JPG

I think one like this would be better 891128.jpg
(i think those links will work, if not I can post full URL)

Hope this helps

Graeme