What should I do here?

take the boat out of the water remove the hull fitting and grind the wooden plate off the hull and replace the wood plate and epoxy back to the hull .
My personal choice is True Design hull fitting and sea cocks there a composite material and are Loyds approved made in New Zealand
They can be purchased at road tech marine at a reasonable cost

www.trudesign.nz/marine/products

www.roadtechmarine.com.au/

question is how long has the through hull been there.
If there's moisture on that wooden pad where is it coming from?Seeping through the hull through fitting or dripping from the ball valve.
You could remove the hull through and sand the pad back if its in good order and either glass it or epoxy it add some cloth over the top
Perhaps it was never epoxied or glass internal and sea water may be seeping into the wood via the sides of the hull through .

www.trudesign.nz/marine/products/70-load-bearing-collars

Ive been thinking of getting some of these collars

I guess the block is there to strengthen it, if ever it receives a knock the block would absorb some of the impact so it wouldn't twist & damage the hull.

I did read on cruisers forum years ago, the cut up plastic cutting board as backing plats wasn't a good idea, as once they start bending/warping, nothing can stop it & it damages the hull, someone at that site did some experiments on it, from memory.... marine ply was the preferred material.

How is chopping board set in mastic any different to plywood? Disregarding rot of course.

I have chopping board on a few places, boart ladder, outboard holder.
I would not use it anywhere under water line.
I did similar repair, use solid piece SS plate on thick layer of silicon.
Anything under water line must be solid, Not even sure about ply.

If it needs to be glued in place cutting boards made of hdpe would be hard to stick. It has a silky smooth waxy texture that resists mechanical adhesion.

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SandS said..

i might be missing something here but , why does it need a chopping board , bit of ply or any thing other than a good skin fitting anyhow ?

is this what new "thin" f/g boats need ? the older f/g boats are 10mm or more thick , direct seal /conntact to hull no problem ?????

It may need some reinforcement behind the skin fitting, yes because the fiber glass layup might be thin, and when you have your stilsons and 4ft of 2" pipe extension, and your trying to close the tap, you don't tear it right out of the hull . Most fittings that need support just have a piece of ply or hardwood glassed in place.

In keensailors case I would chisel out the soft stuff and replace it with "Fibremax", the version with the SS powder not fibreglass particles. Smooth it out to the original shape. Don't do the lot in one go obviously, just work your way around over a period of a few days. When it comes time to replace the fitting you will have some fun but it will give you some piece of mind in the meantime.

I had this problem with 5 sea cocks on Trek when I bought it so slipped the boat to fix. (Mean time put an SMS alarm in the bilge so if it started sinking I would know, including when I was sleeping on board!!).

On the slip when I applied a bit of gentle pressure to twist off the PVC hose attached to the first one the sea cock broke off where the timber is. The other four similar.

My 2$ would be with HG, slip the boat and fix big time.