text: It's actually called camber (I think) as the same principal is used when producing snow skiis.  According to wikipedia: "In skiing, the curvature in the base of a ski."\n\nhttp://en.wikipedia.org/wiki/Ski\n\nBasically it's built on the premise that once you step onto the board, then by virtue of your body weight, you are guaranteed to have the entire board touching the snow.  Plus, it helps while you carve your turns.