Re-Painting bottom of a boat - it is different color of the hull

[Karl Seibel]

Have a 21 ft fiberglass cuddy with the bottom of the boat light blue and the sides dark blue. The sides are fine with a clear coat, but the bottom is chalking. What is the best way to re-paint this? I run my finger on the bottom and the color comes off. I read a site on to paint the hull, do I do the same thing? Thanks...Seibel