Forces on sails to stay within the limitations of a craft's stability and power requirements, which are functions of hull (for boats) or chassis (for land craft) design. Sails derive power from wind that varies in time and with height above the surface. In order to do so, they are designed to adjust to the wind force for various points of sail. Both their design and method for control include means to match their lift and drag capabilities to the available apparent wind, by changing surface area, angle of attack, and curvature. Wind speed increases with height above the surface; at the same
Sporting-Sails Sporting-Sails Sporting-Sails is an outdoor product company specializing in downhill and downwind innovations for skateboarding, skiing, snowboarding, and surfing. The equipment lines are catered towards skateboarders, mountaineers, skiers, longboarders, snowboarders, surfers, and endurance athletes. The company sponsors professional athletes from the worlds of long distance skateboarding, surfing, skiing, snowboarding, and longboarding (including Adam Colton and Long Treks on Skate Decks). Spring 2006, Mill Valley, California born brothers Nick and Billy Smith were looking for fireworks and schnapps in the attic of their grandfather's (Bill Smith Jr.) home in Vail, Colorado, when they discovered his "Ski-Klipper" invention from the late 1960s.