Today most people enjoy sailing as a recreational activity. Recreational sailing or yachting can be further divided into racing, cruising and "daysailing" or dinghy sailing. There are many production sailboats available, and several of these manufactured models have ownership associations, such as the Islander 36 association
Throughout history sailing has been instrumental in the development of civilization. The earliest representation of a ship under sail appears on an Egyptian vase from about 3500 B.C.[1] Advances in sailing technology from the Middle Ages onward enabled Arab, Chinese, Indian and European explorers to make longer voyages into regions with extreme weather and climatic conditions. Improvements were made in the design of sails, masts and rigging, and navigational equipment became more sophisticated. From the 15th century onwards, European ships went further north, stayed longer on the Grand Banks and in the Gulf of St. Lawrence, and eventually began to explore the Pacific Northwest and the Western Arctic.[2]
Wind shear affects sailboats in motion by presenting a different wind speed and direction at different heights along the mast. Wind shear occurs because of the greater friction presented by water surface slowing the flow of air, a difference in true wind creates a different apparent wind at different heights. Sailmakers may introduce sail twist in the design of the sail, where the head of the sail is set at a different angle of attack from the foot of the sail in order to change the lift distribution with height. The effect of wind shear can be factored into the selection of twist in the sail design, but this