Galley drain seacock--backplate space!

[Windtherapy]

Ok so I am changing out all my seacocks (PO never changed them and they are old gate valves--well the sink had a ball valve but still want to change out the thru-hull etc.) and started looking at the one under the sink. How does one get that bottom floor panel off to access the thru-hull better and then, with the ridges in the hull right around the thru-hull base (photo attached) there is no way I can fit a Groco back plate in that tiny opening. What have others done for I am assuming all hulls are the same for at least for the 1985 O'Day 26' and maybe more? Kind of hard to see the ridges in the photo but they are there and about an inch tall.

And then, what are the white cylinders for in the water line (photo attached)? Are they filters or check valves (I am going to assume check valves).

 

[TENACITY CS36T]

White cylinders appear to be just a coupling to connect the two lengths together for previous owner.

 

[Windtherapy]

It would make more sense for these to be little check valves so no water can come up into either sink from the thru hull.

 

[TENACITY CS36T]

Perhaps but it is a pvc threaded coupling

 

[Windtherapy]

Yup that be it.......just a coupler. I assume it probably came from the factory like that. Goes from 5/8" ID to 3/8" ID hose.

 

[TENACITY CS36T]

https://www.google.ca/#q=white+pvc+threaded+copling&imgrc=uEGYiwr0Ps8V8M:

 

[wufibugs]

Given the height of the galley sink, the boat would be largely underwater before seawater could get into the sink. A check valve ain't going to solve that problem.

 

[jibes138]

Not sure what a Groco back plate is but get yourself some G10 material from McMaster Carr and make a backing plate to fit. Are you putting in real sea cocks or are you going with a flanged adapter? Use these instructions, you don't need the hole saw or drill press to cut the G10, a hand jig saw can be used with a metal cutting blade to cut out the G10. !/2 thick G10 is plenty thick enough. I did two of these last year and it worked out great. http://www.pbase.com/mainecruising/replacing_thruhulls

 

[njlarry]

I have replaced three of the four seacocks on my 34. I also did not have much clearance to work on the galley sink drain. The engine and head were easier. For the engine and head I used 1/2 inch marine ply wood. The original plywood backing plates lasted 30+ years with out any problems.
the galley sink used a huge 1 1/2 inch thru hull so I found a small size piece of G10 on ebay. Plywood would also have worked as it did for the original. I cut the G10 with a jig saw and diamond/carbide blades. To get the old thru hull out I cut the mushroom head off outside the hull with an oscillating tool and a metal/wood cutting blade. To install the new seacock inside I had to cut most of the sink locker floor out and replace with 1/4' plywood afterwards. I will add pics once I get used to this WIndows 6 system.

 

[jibes138]

Larry,
I didn't change out the sink drain yet, but plan to on my next haul out, probably next winter. Why did you need to cut the sink locker floor? Assuming the old ball valve set up fit, what was the interference problem that made you cut the floor? I will likely use a real sea cock instead of a ball valve. Is that what you did or did you use a flanged adapter or ??
Thanks

 

[njlarry]

will post a pic when I can. I replaced it with a ball valve on an adaptor plate and I needed the room to prep and epoxy the backing plate. I would have done the same even with a one piece seacock. Will make a 1/4 plywood floor for the cabinet interior.

 

[Windtherapy]

Yup and I will be cutting out the floor tonight as well to change the last thru-hull. It's not fun in the tight space. I cut out part of my floor around the valve just so I could get it off the thru-hull. Mine is a 1/2" thru-hull and valve. I MIGHT just keep the thru-hull in and replace the valve since the thru-hull and backplate are totally solid. I just didn't like the rusted handle on the valve and I am adding a "T" right above the valve for the cooler drain and have already added an isolation valve to the cooler drain line. . .