Paddle Wheels
See also: Paddle steamer and PedaloThe paddle wheel is a large wheel, generally built of a steel framework, upon the outer edge of which are fitted numerous paddle blades (called floats or buckets). The bottom quarter or so of the wheel travels underwater. Rotation of the paddle wheel produces thrust, forward or backward as required. More advanced paddle wheel designs have featured feathering methods that keep each paddle blade oriented closer to vertical while it is in the water; this increases efficiency. The upper part of a paddle wheel is normally enclosed in a paddlebox to minimise splashing.
Paddle wheels have been superseded by screws, which are a much more efficient form of propulsion. Nevertheless, paddle wheels have two advantages over screws, making them suitable for vessels in shallow rivers and constrained waters: first, they are less likely to be clogged by obstacles and debris; and secondly, when contra-rotating, they allow the vessel to spin around its own vertical axis. Some vessels had a single screw in addition to two paddle wheels, to gain the advantages of both types of propulsion.
Read more about this topic: Marine Propulsion
Famous quotes containing the words paddle and/or wheels:
“We approached the Indian Island through the narrow strait called “Cook.” He said, “I ‘xpect we take in some water there, river so high,—never see it so high at this season. Very rough water there, but short; swamp steamboat once. Don’t paddle till I tell you, then you paddle right along.” It was a very short rapid. When we were in the midst of it he shouted “paddle,” and we shot through without taking in a drop.”
—Henry David Thoreau (1817–1862)
“A cruel story runs on wheels, and every hand oils the wheels as they run.”
—Ouida [Marie Louise De La Ramée] (1839–1908)