Repair Hotcoat on a wood laminated surftech

I have a wood veneer surftech that is about 5 years old. I moved from Northern Ca to Maine a couple of years ago and my surftech developed two long cracks in the bottom. They don’t seem to have gone to the veneer but you can easily feel them with a fingernail.

I have heard conflicting information about what the outer layer of resin is on this board(epoxy or poly). I have also heard that you can cause more damage by using poly resin on these boards.

I am wondering if anyone knows about what to use to repair it. I was thinking of putting a new polish coat on the entire bottom but don’t know what kind of resin to use.