Surfing Waves

Hey guys and gals...I'm new here. Recently bought a pretty good Superfish 7S XL, with some dings here and there. Ive been fixing it up. But I have some questions?
Since its got the wood down the middle I'm thinking its PU. Whats best for repairs?
Plus can I use polyurethane resin from the hardware store? or does it have to be surf stuff?
Is the hot coat the same resin that we use to fill the bottom layers?

thanks for all the positivity. Happy surfing!!!!!!!!!!!!!!!!!!!!!!!!!

Do you have pics? I have a Webber SLX epoxy board with a wooden stringer and know of a few local shapers who shape epoxy / EPS boards with stringers as well so seeing a stringer is no guarantee even on a factory board like a 7s.