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
North Sails which the company markets as the 3Di product line. North Sails North Sails is an international sailmaker with operations in 29 countries. The company designs, engineers and manufactures sails for racing and cruising sailboats from 8 feet (2.5m) to more-than 200 feet (60m) in length. Licensees manufacture clothing and windsurfing sails. North Sails is the world’s largest sailmaker, with annual sales of $150 million in 2011. Sails by North Sails are used by the majority of competitors in the Volvo Ocean Race and the America’s Cup. North Sails was founded in 1957 by Lowell North, in San Diego, California. An