I have had good luck with straight white gelcoat making a good match on Nacras. The repair I did on our Infusion matched perfectly (white gelcoat from http://www.uscomposites.com/) and I had the same great match with a repair on my '04 F18. I can't promise that all whites are the same...AHPC uses a touch of grey in their white gelcoat and are really nice that they include this coloring information on a laminated decal inside the hulls. You should be good to go with a standard white on the Nacra. I have the vendor info in California that Nacra used for their gelcoat if you need that too (I'll have to find it).