Paddle wheel

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A paddle wheel is a large wheel fitted with paddles which is used to propel a boat. Paddle wheels powered by steam engines were the means of propulsion for the paddle steamers of the nineteenth century when the technology reached the height of its popularity, but paddle wheels powered by other means were apparently known about long before, by the Byzantines and ancient Chinese.

During the late nineteenth century, the steam powered paddle wheel was gradually replaced in ships as a means of propulsion by the screw propeller, which utilized energy much more effectively (30% wasted energy as opposed to 70% for a paddle wheel). Another problem with paddle steamers is that they were difficult to steer in rough weather, as one or another of the paddles on the side of the ship left the water as a wave passed under the ship, causing the paddle on the other side to turn the vessel.