This volume replaces Marchaj's classic Sailing Theory and Pactice, published 25 years ago, and offers new information on, rig design, sail construction and trim, wind-sail interaction, and the structure of the wind. The performance of any sailing craft depends largely 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 and shape, and steadiness of the wind, among others. From wind-tunnel tests that he has conducted, Marchaj describes how these factors affect sail power and why certain rigs are superior in power and efficiency--concluding that the Bermuda, or marconi, rig is by no means the best available. This major work is an accessible, nonmathematical treatment of the subject and marks a turning point in modern thinking in the arena.