Boards these days have a variety of features on the bottom which can accomplish several different things. Some boards have channels running lengthwise down the bottom of the board, which serve two functions. They provide additional traction against slipping sideways and they accelerate the water flow beneath the surface by breaking surface tension, adding to overall speed. If you think of a dinner plate being set on a wet table, and the suction that is created, the principle is the same. These bottom contours can break up the suction and, in theory, accelerate the board. Another feature commonly seen, especially on more aggressive boards with larger rockers, are spines running down the center of the board. These spines are smooth, slightly raised sections on the bottom of the board. The spine comes into play when the board is landing from the air; the spine hits the water first and begins to break up the surface tension before the rest of the board hits. This softens the slap the board has on the water and eases the impact on the rider (think dive vs. belly flop).
