For: Sailing (song)

Sailing is the art of controlling a boat with large (usually fabric) foils called sails. By changing the rigging, rudder, and dagger or centre board, a sailor manages the force of the wind on the sails in order to change the direction and speed of a boat. Mastery of the skill requires experience in varying wind and sea conditions, as well as knowledge concerning sailboats.

Current use

In most countries people enjoy sailing as a recreational activity. Recreational sailing or yachting can be divided into racing and cruising. Furthermore use of sailboats can be divided into long-distance sailing (also blue-water sailing or offshore sailing) and daysailing.

History

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. 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.

Introduction

A sailing vessel moves forward because of the reaction of moving air on its sails. Since the dawn of history this vital technology has afforded mankind greater mobility and capacity for fishing, trade and warfare. From moving the stones of the great pyramids from Aswan to Giza to allowing man to migrate throughout Polynesia to Nelson's defeat of the French and Spanish navies at the Battle of Trafalgar, mankind's history has been intertwined with this seemingly simple technology.

Energy capture

Sails are airfoils that work by using an airflow set up by the wind and the motion of the boat. The combination of the two is the apparent wind, which is the relative velocity of the wind relative to the boat's motion. The sails generate lift using the air that flows around them. The air flowing at the sail surface is not the true wind. Sailing into the wind causes the apparent wind to be greater than the true wind and the direction of the apparent wind will be forward of the true wind. Some extreme design boats are capable of traveling faster than the true windspeed on some points of sail.

The sail alone is not sufficient to drive the boat in any desired direction, as a sail by itself would only push a boat in the same direction as the wind. Sailboats overcome this by having another physical object below the water line. This may include, a keel, centerboard, or some other form of underwater foil or even the hull itself (as in catamarans without centreboard or in a traditional proa). Thus, the physical portion of the boat which is below water can be regarded as functioning as a "second sail". Having two surfaces against the wind and water enables the sailor to travel in almost any direction and to generate an additional source of lift from the water. The flow of water over the underwater hull portions creates a hydrodynamic force. The combination of the aerodynamic force from the sails and the hydrodynamic force from the underwater hull section allows motion in almost any direction, except straight into the wind. This can be likened, in simple terms, to squeezing a wet bar of soap with two hands which causes it to shoot out in a direction perpendicular to both opposing forces. Depending on the efficiency of the rig, the angle of travel relative to the true wind can be as little as 35 degrees to over 80 degrees. This angle is called the tacking angle 1. With a 35 degree tacking angle on either side of the wind, it is possible for a sailboat to sail directly over 290 degrees of the compass (360 - 2x35 = 290 degrees).