gelcoat repair

I posted a new pic in the gallery but it dosn't due justice cause it's hard to see the hack job done to the bow. Anyway it's about a 5 inch gash/repair job along the center, the seem is all jagged and you might be able to see the gelcoat sanded away in about a 10" radis around the injury.What should I fill this with so it can be sanded smooth, and what do I apply aferward to bring back the shine back? For her age she cleans up well but this injury is buggin me. :(