Kenny,
DO NOT USE MARINE TEX or any other epoxy based product. Go to West Marine and get some Formula 27. Clean out the damaged area and fill in with Formula 27. Sand smooth, apply gelcoat, sand again then buff. Your repair will be good as new. Epoxy based products will adhere to polyurethane resins but resins do not adhere to epoxies. If you were to use Marine Tex then cover with gelcoat...the gelcoat will not cure and you'll have to start all over again. Just get the Formula 27. It's what I've used for my Tiger hull repairs. You'll be much happier.

John Bauldry
Commodore, Hobie Fleet 276
Hobie Tiger #1704