“The Advantages of Transverse Battens. Practice has proved that in light airs a strongly arched sail is superior while in heavy winds a somewhat flatter sail is preferred. This is confirmed by nature in that the wings of slow flying birds show greater arching than those of fast flyers. For this reason most of the international metre boats have several sets of sails, either cut flat or strongly bellied.
Just before the race a decision is made as to which sail is to be used in the prevailing wind. The question arises: Why not use a sail with a changeable arch? Must we go as far as China or Egypt to learn what a sail should look like? Must we be reminded that the kite with a rigid surface flies one-third higher than the one which is bellied by the pressure of the wind?”
Dr Manfred Curry – Yacht Racing: The Aerodynamic of Sails (1948)
(Born in Munich in 1899 to an American father and Russian mother, Curry was a skilled sailor and represented the USA in the 1928 Olympics. His various inventions and pioneering books on yacht aerodynamics and design are among the most significant contributions to the science of sailing. Curry’s pre-war experimental dinghy Aero – above – looks remarkably like the latest AC75s.)