I fear I may be doing this wrong Trying to leave a comment here spork From the start of this wiki page Devices that are powered by sails such as sailboats iceboats and sand yachts can sail that is advance over the surface faster than the wind Of course they can not do that by using simple square sails that are set perpendicular to the wind Actually I m pretty sure it IS possible to sail faster than the wind with a square sail set perpendicular to the true wind However the vehicle must be constrained to move at some angle to the wind Consider an ice boat one a downwind course 110 degrees off the wind With a square sail and low enough drag the ice boat should maintain a downwind vmg of nearly wind speed with this configuration That will give it a true speed far greater than wind speed