Longtime color matcher here. Make sure you match to an area of the hull
near your repair that has been wet sanded and buffed to bring it to its original color. Otherwise you will be matching to your oxidized hull
. And definitely match close to the area you are going to repair-its amazing how much color difference you can get between areas that are in theory the same color. And finally, the secret to good color matching. It's hard to explain in text but i'll try. Cut up some pieces of CLEAR mylar about 1" square. If you cant get any cigarette cellophane works fine. After wet sanding
and buffing the area you will match too, start mixing your color. When you think you are close, daub a drop or so onto the spot you are matching to. Then take a square of mylar and lick one corner of it to get some spit on it. Put the dry corner of the mylar onto the gelcoat drop and the spit corner onto the surface you are matching to. Then gently tap the mylar until the gelcoat and the spit run into each other. This will give you a clear hard line between your match color and the original color of your hull, allowing for a comparison. It's hard to explain why this works, but believe me it does. I've done thousands of matches this way, it's an old pros trick. People bring their color matches to me instead of the computerized matching people because the computer never gets it quite right, whereas my matches are almost always perfect. Even on colors other than white. Try it and you'll see why it works. Prep good and have fun!