The common sailboat comprises eight essential parts: hull, tiller, rudder, mainsail, mast, boom, jib and keel. The hull is the shell of the boat, which contains all the internal components. Its symmetrical shape balances the sailboat and reduces drag, or the backward pull caused by friction, as it moves in the water. Inside of the hull in the stern, or back of the boat, is the tiller, which is attached to the rudder in the water. Think of the tiller as the boat's steering wheel and the rudder as the tire. To maneuver a sailboat to the right, for example, you pull the tiller to the right side of the boat, causing the rudder to alter its direction.
If you think of the tiller as the steering wheel, then the sails and the keel are the engines. The mainsail is the larger sail that captures the bulk of the wind power necessary to propel the sailboat. Its vertical side attaches to the mast, a long upright pole, and its horizontal side secures to the boom, a long pole parallel to the deck. Sailors can rotate the boom 360 degrees horizontally from the mast to allow the mainsail to harness as much wind as possible. When they pivot the boom perpendicular to the wind, the mainsail puffs outward. Conversely, it goes slack when swung parallel to the wind. This freedom of movement allows sailors to catch the wind at whatever angle it blows. The jib is the smaller, fixed triangular sail that adds additional power for the mainsail. The keel, a long, slim plank that juts out from the bottom of the hull, provides an underwater balancing force that keeps the boat from tipping over. In smaller sailboats, a centerboard or daggerboard serves the same purpose as the keel, but can be raised or lowered into the water to allow for shallow water sailing.
Before a boat can move in the water, it first must be able to float. In the next section, we'll discover how something as heavy as a sailboat can stay afloat.