Plywood coated in a layer of sealant then painted over

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FairweatherDave

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In the process of stripping my deck I have uncovered a layer of plywood sandwiched between the deck and the forecabin hatch. This would have been inserted when the previous owner replaced the original hatch with a Lewmar one. In the process of stripping off the Interdeck over the ply I have discovered a layer of sealant. This I am scrapping off too as there is a tiny proportion which has got water ingress which needs making good. Is this coating using sealant a standard practice over ply? But more importantly I am wondering how to repaint the ply (ie which paints to use) as I won't be Interdecking this. Thanks for any advice.
 
Sealant not the best idea, but if the thickness of the ply is small and irregular and the sealant is of a type that will take paint then it should work. Presumably it is end grain and the best way of dealing with it is to epoxy to seal it and then paint. Might be a bit of a challenge to get all the old sealant off to prepare for epoxy.
 
I use Resoltech resins. One of them (RE1010) is a water based coating that is also used to 'stiffen up' old wood in buildings. It is a great coating on ply and is not unhappy if the wood is a bit 'humide', as it displaces water. While I am not reccomending ignoring rot, a marginal case can be fixed with this product.
Usual disclaimers, it just works for me.
 
Thanks both. The plywood is probably 2cm wide at most all round the hatch and is probably 12mm thick. It has been coated with a good 1 or 2mm of sealant under the deckpaint. I can continue to sand and scrape it off but then the surface will be bare wood with hints of sealant residue worked in. It is going to be repainted with something. Sounds like the Resoltech RE1010 would be a candidate as a coating. I was considering the "Ronseal ? wood hardner" you inject in rotten wood for the very small bit that has got "humide". Equally I could recoat with another rubbery sealant and ordinary dometic exterior wood paint. I initially thought epoxy but the wood has to be bone dry for that? Obviously I could replace the ply and rebed the hatch but that is overkill at the moment.
 
You'll probably get away with bodging sealant around the hatch externally for the season if time is tight - if at all possible when you come to do it try to preserve the shape of the old ply under the hatch to use as patterns for better wood - which is not so rare or expensive as it used to be.

I have unbolted and re-seated my forehatch on sunny days even at the mooring.

Be very wary in case water has ingressed sideways into the deck around the hatch; depending on the material of the deck construction this could range from a medium level inconvenience - balsa filled decks - to a right serious pain - foam sandwich decks...
 
In the same style, Sikaflex 11FC is a PU adhesive, sticks to just about anything and can be painted over. Doesn't mind the damp, as it helps it to go off. Stays slightly flexable. Only €7 a cartridge in the local B&Q.

As for Re1010, the local stockist has it for €50 for two kg, so bit pricey for a small job. Plus, it needs to be stored at a decent temp. Too cold and it tends to degrade. so limited shelf life. Even kept comfy, I find it will only last a year or so. I have conventional époxy that is 10yrs old and still good, in fact, building a pocket cruiser with it right now. I lucked into a 200ltr drum from a failed project, along with assorted hardeners :o) I do tests from time to time, but still sound.
 
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