The determination of aerodynamic forces on sails-challenges and status

It is important to be able to determine the forces on the sails of racing yachts and square-rigged historical vessels, as well as for potential commercial vessel applications. This problem is very complicated due to qualities of the sailing environment, viscous flow physics, and the need for accuracy. Three methods are currently being used to determine these forces-full-scale testing, wind tunnel testing, and computational fluid dynamics. Each of these methods has advantages and disadvantages relative to the sail aerodynamics problem, and these are discussed. Advances in our understanding of sail aerodynamics will require continued research using all three methods, and some suggestions for future research are presented.