Ok if its been sealed then it looks like the water has been getting in for some time and has got into the ply.
What came out on the drill bit didnt look good.
But like I said there is no bounce or spongyness in the deck.
I am seriously considering putting a deck hatch in at the back
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at least I will be able to see whats what.
what do you all think?
also a drain bung.