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Head & sink complications

Hi there!
I have some difficult time figuring out head and sink. In my C36 mkII there is two valves in the toilet and the shower pump in the toilet bildge
1) The one described in the manual as THRU HULL VALVE FOR SINK DRAIN has plate SHOWER SLUMP and I am able to push it 180 degrees
2) The one described in the manual as ​THRU HULL FOR SHOWER DRAIN has no plate and has hose connected to some water pump just by the valve and I am able to push it 90 degrees

In the saloon there is valve for the macerator pump. What is interesting I found out the 3 way switch near macerator pump. When on the main panel macerator pump is turned on and the switch is turned left, then macerator pump works, when the switch is in the middle nothing is working and when switch is on the right then previously mentioned pump in the toilet is working.

1) What can be this pump in the toilet function?
2) I cannot hand pump the water into the JABSCO head -both of settings works as pumping out, can be this gasket problem?
3) The sink has some water/fluid in it which doesn't want to drain -how to let it drain?

Any help appreciated

KevinLenard's picture
Last seen: 1 week 4 days ago
Joined: 1/28/15
Posts: 153

Of the two thru-hulls in the head, one is the drain for both the sink and shower sump pump.  The pump you are talking about should be the sump pump that extracts the water from the catchment basin under the floor board through a plastic pipe that ends in the lowest part and empties the shower water out of the boat.  The drain thru-hull SHOULD have a T-connector that shares the drain between the sink drain hose and the outlet from the sump pump.  If the handle on either thru-hull can turn 180 degrees, I suspect it should be replaced, but I have the Mk 1.5, so this might not be the case on the Mk II. 

The other thru-hull is the INTAKE for the toilet water -- it needs to be open  (lever pointing down) to allow water to enter the toilet when the toilet is pumped.  From your description it sounds like you have the thru-hull closed and no water is being allowed up into the toilet -- but there also can be a problem with the flap gasket in the toilet pump handle that is preventing the water from entering.  It is easy to open and take a look via the 4 screws on the handle IF, after turning the valve at the thru-hull to open, no water goes in.

As for the 3-way switch, it is supposed to be an either-or switch -- it works to pump the black water out into the ocean ONLY when you choose to empty the tank in that manner.  Regulations in many harbours and rivers do no allow for emptying the black water out into open water, only for pump outs at marinas that pump the water into the local sewage system.  I'm not sure why the 3rd setting switchs to the sump pump being powered on, but I'm not 100% clear which pump you are referring to.  Might just be a convenient way to remind you which setting the switch is turned to. 


Kevin Lenard
'91 C-36 Mk. "1.5" Tall Rig, Fin Keel, Hull #1120, Universal M-35 original (not "A" or "B")
CBYC, Scarborough, Lake Ontario, Canada

Last seen: 2 months 1 week ago
Joined: 2/17/19
Posts: 30

To better visualize I'm attaching photo with the two mentioned valves and water pump which is turned on via 3 way switch.

So for now what I'm going to do is replace jabsco top gasket and I will also check vent line if it isn't clogged.

Chachere's picture
Last seen: 1 day 2 hours ago
Joined: 10/27/10
Posts: 636

The picture helps -- but its not clear from it where the hose that is topmost at the left edge of the picture is going.  Is it conneect to the left seacock, or is it tee-ed into the hose that is bottommost at the left edge of the photo?

In any event, I think the only way you are going to figure this out is to trace each hose and then draw a schematic of the plumping arrangements.  While the stock C36 has 2 seacocks in that location, various owners (me included!) have reconfigured the hose arrangements over time to suit various needs, so I think its going to be hard for others on the site to give you a clear answer --- that is, we can tell you what how it works on our boat, but not necessarily yours.

For example, from the label on the pump in your photo, it appears to be not the sump pump, but rather a deck wash-down pump that was added by a previous owner.   If that's the case, I would expect that the 2 seacocks are indeed serving 4 different hoses with 4 different functions, in no particular order:
- water intake for the  head
- water intake for the washdown pump
- water discharge for the sink
- water discharge for the shower sump pump
Again, that's why you're going to need to trace and sketch out the plumbing scheme, because its already obvious that this is not a "stock" arrangement, simply by virtue of the addition of the washdown pump

BTW, the shower sump pump, as least as originally installed, would be an immersion pump sitting in the sump itself, and feeding the hose that's coming from the bottom right hand corner of your photo; that line should run up to a vacuum loop up behind the cabinet above the head, and then back down to one of the seacocks.  

As to the 180 degree rotation on one of the seacocks:  That's not supposed to happen; probably the internal stop has broken.   The handle should be able to point either upright or 90 degrees (i.e., to the right), but not down).  Our boat has a seacock (in a different location, for the macerator) that has that issue and which at some point I'll probably replace, but as a practical matter its rarely used (as the macerator can only be legally operated when we're several miles offshore in open ocean) and does continue to serve its intended purpose as long as we set it at 90 degrees whan we want it closed.



Matthew Chachère
s/v ¡Que Chévere! #466
1985 C36 MKI tall rig fin keel M25
Homeported in eastern Long Island, NY

Last seen: 2 months 1 week ago
Joined: 2/17/19
Posts: 30

Thank you very much.

I will do the fixes first and then try to figure it out based on the provided help.

pkeyser's picture
Last seen: 12 hours 32 min ago
Joined: 5/18/13
Posts: 444

Of the two head thru hull valves I have in our MKII, one (the sink drain/washdown pump) also has a handle that rotates 180 degrees. I thought that was odd, and while the boat was on the hard, I disassembled it, expecting to find a broken stop somewhere, but couldn't. Instead, it appears to have been designed that way. All the other valve handles in the boat have 90 degree of rotation except for that one. The top part of it appears to be designed differently. In any event it operates fine, as long as you place the handle in the correct position. Maybe its designed that way to increase flexabilty of use. If a 90 degree valve were installed in tight quarters and oriented the wrong way, you might have to pull it out and reorient it so you could rotate the handle with enough room. A 180 degree valve is more forgiving to orientation in tight spots????


Paul & Wendy Keyser
"First Light"
Newburyport MA/Rye NH
2005 C36 MKII #2257
Wing, M35B

Last seen: 2 months 1 week ago
Joined: 2/17/19
Posts: 30

Confirmed, works properly.

I also replaced head gaskets and now water is pumped properly.

Still didn't figure out what is this additional pump responsible for.

Thanks guys!

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