Fred - It's tricky to match the white color. I think I got pretty close on my 23 using this recipe.
a pint of Natural gelcoat
a pint White gelcoat
approx 1/2 teaspoon spoon of halyard off white pigment from UScomposites
(and then mix entire batch with 25% clear duratech).
Start with a smaller batch and use an eye dropper (with the pigment) to achieve desired color. As you get close to a match . . . test by putting drops on the boat to match (without MEKP hardener) . . . just wipe off with acetone.
Spraying with Gelcoat is a LOT more work than paint. You will prep the surface . . . spray a bunch of coats . . . It'll look like crap with all the orange peel. Then you get to sand with 320, wetsand 400, 600, and buff with rubbing compound/polishing compound and then wax.
http://www.uscomposites.com/pigments.html
