Jon,

Having built a Coho and painting both hull and deck with Interlux Brightsides, it is my experience that Brightsides is not the paint to use. The paint is just not tough or hard enough. It will scratch down to the glassz/epoxy layer easily. Also, Brightsides takes 16 hours to dry -- per the instructions on the paint can -- on dry hot days. I,ve had to wait 4 days between coats to wet-sand to prevent balling of the paint under the sandpaper. I suggest looking into two part paints. Call the paint companies, and tell them your painting a kayak which will be in the water X amount of hours per week ask their advice on the type of paint that will withstand the abuse of piers, rocks, sand, cartops and water. It will most likely be a two part or pigmented epoxy. If you are set on a one part paint then Z-Spar has a good 4 hour cure paint line. Good luck -- enjoy the sanding!!
Bill