SAIL PERFORMANCE - TECHNIQUES TO MAXIMIZE SAIL POWER

'Sail Performance', based on C. A. Marchaj's classic 'Sailing Theory & Practice', has established itself as the standard work on the subject and is now acclaimed as a milestone in sailing literature. The performance of any sailing craft largely depends on the power of the available sail—how the rig uses the wind and turns it into a useful driving force. But sail forces are determined by a multitude of factors, including wind speed, sail area, sail shape, sail setting, the hull, angle of heel, wind gradient, and steadiness of the wind. From wind tunnel tests which he has conducted, Tony Marchaj describes how these factors affect sail power and why certain rigs are superior in power and efficiency to others. The tests also indicate where improvements in efficiency may be made, particularly when freed from the constraints imposed by the arbitrary limitations of the racing rules. Professor Marchaj compares a number of different types of rig—Bermudan, lateen, sprit, gunter, dipping lug and Polynesian crab claw—and concludes that the Bermudan rig, which dominates the contemporary sailing scene for racing and cruising, is by no means the best available. This major work makes a significant contribution to our understanding of the factors which contribute to an efficient sailing rig, and is a landmark in modern thinking on the subject.