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 Nick and Billy Smith tested the drogue parachute/wingsuit flying-like device on skis before attempting to try on a skateboard in the hills surrounding the Marin Headlands and San Francisco, California. On a skateboard, creating drag at will by deploying the Sporting-Sail during the descent enabled Nick and Billy Smith to control their speed and stability on steeper terrain. For many years Sporting-Sails was based in Ventura, California, close-by to Patagonia (clothing) HQ, where Billy Smith currently works full-time as their wetsuit developer. Currently, Sporting-Sails HQ's are back in the shadows of Mt. Tamalpais in Mill Valley, California. The Sporting-Sail logo