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
San Diego Sails of 1975 to Frank Goldberg, a former co-owner of the successful Denver Nuggets franchise. Goldberg started anew, renaming the team the San Diego Sails for 1975–1976. Goldberg hired former University of Minnesota coach Bill Musselman and, with a completely different roster, color scheme, set of uniforms and just about everything else, sought to repeat Denver's turnaround a season earlier from mediocrity to championship contender. But the Sails attracted only 3,060 fans to their home opener on October 24, 1975 – a loss to the Nuggets – and fan attendance rapidly dwindled further as the team limped to a 3-8 start.