Achieving high speeds on the water requires a hull that easily transitions into the planing mode. Characteristics of a planing hull include flat bottom surfaces from amidships aft (from the middle to the back of the bottom) and flat transom (back of the hull). The transom must meet the bottom at a sharp angle. At certain speeds that vary with each bottom, the boat is supported by the same dynamic forces that keep a water skier on top of the water.