Michael,

I purchased my first carbon mast in 1994 for my Nacra 5.5 Uni. I left it on the trailer in the sunlight all summer long but would bring it inside for winter storage (November thru March). This boat and mast are still competing without issue. It is a production mast from Performance and came painted white. I did nothing extra to protect it. I don't think there is any problem with moisture or UV for the painted carbon masts.