Jeff
One trick I've found useful when doing gel coat touch-up is to get hold of a sheet of the old overhead transparency film and cut a piece oversize for the patch area.
Use masking tape to form a hinge along one side. after you fill the void and scrape any excess away (razor blade held near perpendicular to surface does a fair job for small areas) place the film over the patch and tape over it of the opposite side. The patch takes on the super smooth surface from the film and makes final finishing much easier.
Many /most gel coats need to have air excluded to cure properly - the film accomplishes that as well.
If you have to tint the gel coat to match the boat - especially when aged - a piece of the film makes a great place to mix the gel coat and tint as you can do it on the boat surface and view the mixture with the background you are trying to match after you are satisfied with the match then you can add the catalyst to make it harden.