I do not know how old the boat is but you should find out if the deck
is balsa cored. If so, it is very likely that water
intrusion has created rot
in the wood core
. If that is the case, you will want to go ahead and cut away the decking from the top as far back as needed to eliminate the rotted areas. Then replace the balsa with klegecell foam and glass back over it with epoxy
. you may use various fillers for the different conditions and engineering needs. Scarf the edges and fair out the repair.
Now the real work begins...refinishing the entire deck