Use polyester gelcoat (if thats whats originally on the boat)of the same color.
If all it is the color (gelcoat) don't make it more of a problem than it is by adding cloth if it is not necessary. The last thing you want to use is Kevlar...when you try to sand (or the resin is ground away by beach sand) it makes little fur balls. It doesn't sand like fiberglass, you can't feather it. Don't use epoxy unless your going to use paint over it.

Regards,
Bob