What does hull speed mean?

Hull speed is the theoretical limit of a sailcraft's speed. It can be approximated by the following formula: 1.34 * SQRT(LWL), where LWL is the length of the waterline, in feet. As a small vessel approaches its hull speed, the hull begins to climb its own bow wave. The faster the vessel tries to go, the more difficult climbing the bow wave becomes. Eventually, should the hull type permit it, the hull will begin to hydroplane (skimming across the water.