|1.||nautical a pivoted vertical vane that projects into the water at the stern of a vessel and can be controlled by a tiller, wheel, or other apparatus to steer the vessel|
|2.||a vertical control surface attached to the rear of the fin used to steer an aircraft, in conjunction with the ailerons|
|3.||anything that guides or directs|
|[Old English rōther; related to Old French rōther, Old High German ruodar, Old Norse rōthr. See |
part of the steering apparatus of a boat or ship that is fastened outside the hull, usually at the stern. The most common form consists of a nearly flat, smooth surface of wood or metal hinged at its forward edge to the sternpost. It operates on the principle of unequal water pressures. When the rudder is turned so that one side is more exposed to the force of the water flowing past it than the other side, the stern will be thrust away from the side that the rudder is on and the boat will swerve from its original course. In small craft the rudder is operated manually by a handle termed a tiller or helm. In larger vessels, the rudder is turned by hydraulic, steam, or electrical machinery.
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