Anchor winch support

[tumblehome2]

Hello all,

I have done reading and reading and going about in circles without actually finding much......
Everyone refers to gelcoat over epoxy.... but what about epoxy or other resin over gelcoat.

The interior of the bow is mostly covered in white presumably a gelcoat (not certain) My mission is to add support structure (25mm ply) under the deck and wonder if an epoxy bond, or 5200 or anything else advisable to add the ply to underside of deck. No fibreglass in contruction.