seacock overkill?

[jim99]

I'm installing a couple new Blakes seacocks for my new head and I've read lots of pros and cons about the various 3M, Sika and other products and thicknesses and types of backing plates, etc. This is what I might try if it's not judged overkill by kind and knowledgable forumites.

Drill the inlet and outlet holes. Fit and shape 15mm (1/2") plywood backing plates that have been treated with epoxy (marine plywood seems impossible to find here). Seal backing plates. in place with 3M-4200.

Let cure a bit. Drill bolt holes. Glass over with a sheet or two of fibreglass with appropriate holes cuts, and bolt down the seacock with sealant before it all sets hard.

Figure the sheets of glass would provide an extra bit of security and glass is easy enough to remove with a sander if it ever needs to be replaced.

Overkill?

 

[DanTribe]

Generally speaking it's much better to have it too stong than a bit too weak.
I might be slightly concerned with sealing in timber out of sight in a damp area where rot could start. For that reason perhaps better to leave it exposed or use something inert, e.g. more GRP.
It's interesting that you can't find marine ply there, most of our 1088 ply seems to come from the far east.

 

[jim99]

Good point about keeping an eye on rot, Dan.

Maybe I am not looking in the right place. I am now in Bangkok. Perhaps if I was in Phuket it would be all over the place.

 

[Danny Jo]

[ QUOTE ]
I might be slightly concerned with sealing in timber out of sight in a damp area where rot could start.

[/ QUOTE ]

Provided the timber is dry when sealed by coating in epoxy, you shouldn't have a problem. Wood epoxy boat construction works on this principle. Freestyle's wood epoxy hull was tested earlier this year by a surveyor, who reported that the moisture content was the same as it should have been when she was built 18 years ago. For evidence of 35 years survival, read this

Problems with rot arise mostly because modifications are made by people who do not understand the principle, and drill or cut through the epoxy without resealing.

 

[jim99]

Freestyle, appreciated the link. Perhaps the epoxy is enough based on its track record... and I worry about things too much /forums/images/graemlins/smile.gif

 

[DanTribe]

Hi
I'm convinced of wood epoxy's longevity. I built a Y-Emma dinghy 25 odd years ago with West and despite years of hard use & neglect it's still sound.
I assumed he was going to bond the backing ply in with 3M 4200 [polyurethane?] then cover in GRP [epoxy or polyester?] then drill bolt holes. Not sure of the sequence, but several opportunities for water ingress. Anyway, not a major concern but better to do it correctly once.

 

[jim99]

First time installing seacocks so appreciate any comments.

Actually, was planning to bond/seal the backing plates (which will already have been treated with a few coats of epoxy and have the inlet/outlet holes drilled) to the hull with 3M-4200 (polyurethane). Would then drill the bolt holes through plates and hull, take away the seacocks, and glass a couple layers of mat (I have polyester resin) over the plates. Then reinsert the seacocks, squirt 4200 into the holes and bolt it down.

Now I'm thinking that's foolish. Why treat it with epoxy if you are then going to drill bolt holes and leave it vulnerable.

So I will simplify, forget the glass and trust the epoxy: drill all holes in backing plates, treat with epoxy, drill inlet/outlet holes in boat, seal backing plate to hull, drill bolt holes in boat, fill with sealant, bolt it down.

cheers