Nautical Term: Propeller
Definition of Propeller
A propulsive device, commonly found on watercraft, is referred to as a propeller. This device consists of a hub or boss, onto which radial blades are attached. The number of blades can range from two to four. The rear or driving faces of the blades create portions of an approximately helical surface. The axis of this helical surface serves as the centerline of the propeller shaft.
For example, consider a sailboat with a 10-foot long keel and a single propeller at the stern. The propeller is designed with a diameter of 4 feet and three blades. When the sailboat is at rest or moving slowly, the sail provides most of the forward motion. However, when the sailboat needs to accelerate or navigate in reverse, the propeller comes into play. By turning the propeller in a clockwise direction, the sailboat is able to move forward at a faster pace. Similarly, by reversing the direction of propeller rotation, the sailboat is able to move in reverse.
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