Sail Change

Sails optimally matched to conditions offer the fastest sailing performance. Too little sail is too little power, and too much sail is dangerous and often slower as well. For thousands of years, sailboats only changed sails when they wore out. Sails could be depowered by easing the sheets, or by various Furling methods. As the Golden Age of Sailing developed a few hundred years ago, Light Air Sails became a cumbersome option, added to the basic Sail-Plan in calm conditions, and small robust Storm Sails also began to become common.

In modern times, starting about a century ago, Sailboat Racing adopted frequent Sail Changes, under pressure of competition. It became a common Racing principle that time lost in Sail Change was more than made up by performance gain once Change was made. Sailboat Racing has continued to radically develop Sail Changes to where virtually no time is lost changing a sail, as a new sail is put up before the old sail is taken down. Thus Sail Changes are more important than ever. Especially over a long race, where a wide range of winds is encountered, Sail Changes radically boost performance, and even Cruising Sailboats change sails as conditions vary. Ever more specialized sails have evolved for even lighter and heavier winds, expanding the range of High-Performance Sailing to virtually all conditions.

Ironically, in AWE R&D, the design assumption has often fatally been One-Wing-does-All, based on Wind Turbine Blades. In Aviation, virtually all aircraft have radical high AoA modes and Flaps to help Take-Off and Landing. Transport Jets have elaborate Slat and Flap modes approximating Sail Change states. The most exotic aircraft, like Space Shuttles and Fighters, even have true Sail Change by deploying Drogue Chutes. Because Aircraft move with wind and count on long runways, they can spend most of time at Optimal Design Velocity, and limited wing state-changes are good enough. Traditional Wind Turbines change Sail Area, and researchers propose future Wind Turbines might well do so again.

In Kite Sports, Sail Change is Standard. Even casual enthusiasts tend to own a "Quiver" of kites of various sizes to match conditions. kPower has long proposed that Large-Scale AWES based on Low-Complexity Sails may also depend on Sail Change as a Basic Enabling Method to match Conditions to Load-Demand. Far from being a clumsy primitive dependency, Kite Quiver Sail Change is the most advanced technological option, based on parallel evolution in Sailing Wind Tech. Sail Change also resolves concerns about Sail Life-Cycle, as Sails are always kept within Design Limits and their already long UV life is multiplied by the number of Sail Change States. We are even learning to analyze AWES in terms of Dynamic Topology, where Sail Change is is classed as Topological Surgery, a Mathematical-Engineering frontier.