How Sails Work

History

Sails powered the ships of merchants and navies for centuries. Sail power was eventually replaced with steamships in the early 1900s. Although sailing was no longer utilized for commercial or military ships, it became a popular recreational form of boating. Sailboats come in a variety of sizes and styles. The most popular of sailboats are the catboats and sloops. Catboats have just one mast, positioned towards the front of the boat, and one sail. A very small catboat, typically used by children, is called a sailing dinghy. The sloop also has just one masthead, yet it is positioned in the middle of the boat, and has two sails. The two sails are called a mainsail and jib. A cutter is a large sloop with two jibs. Larger and more costly sailboats include schooners, ketches and yawls. These types of sailboats typically have three or more sails, and might have living quarters on the craft.

Sailboats are designed to harness and capture the wind in the sails to move the boat. The basic parts of a sailboat are the sails, spars, rigging and hull. The largest sail is the mainsail and it is fastened to the back of the mainmast. The smaller and triangular shaped sail is referred to as the jib. The large balloon shaped sail is called the spinnaker. Its purpose is to capture wind for increased speed. The spinnaker is typically made from nylon, while the other sails are made from Dacron or cotton. The hull is the body of the boat, the spars are the poles or masts that support the sails and the rigging is the ropes or line to help support and control the spars and adjust the sails.

Curved panels are sewn into sails, so that when the wind fills the panel it expands to a shape similar to the wings of an airplane. When sailing it is possible to manipulate the force of the wind to propel the sailboat in any direction, except directly into the wind or 45 degrees on either side of this direction. This is possible by manipulating two forces. The first is the force created when the panel is filled with wind and it creates a lifting force that causes a pull towards the front of the boat and away from the sail. The second force is created when the wind pushes against the other side of the sail. Maneuvers to manipulate these forces include sailing into the wind, sailing across the wind or sailing with the wind.