[QUOTE=rwidman;3392825]I believe gelcoat is incompatible with epoxy. I plugged some holes with wood
and epoxy and later had a gelcoat guy cover them with gelcoat. It all flaked off after a few months.
This is not entirely correct-watch Andyís vids (Boatworks today) he ran a series of tests (admittedly not scientific) bonding polyester (gelcoat) to epoxy. Way stronger than everyone says - but you must get rid of the amine blush & properly prep the surface because itís a mechanical bond, not a chemical bond.
For your situation, wash carefully, then drill out 0.5 mm more depth
, then you are good to go with with gelcoat. Overfill slightly as it will shrink slight on curing. Matching the non skid is really hard, but small-medium holes with decent color match will look fine. Only you will notice.