ORIGIN
The rudder came into invention because of the evident inefficiency of oars (and their ability to be used to steer) with the increase in speed during ancient voyages. Sailors from various seas adapted different variations of the simple rudder.
Rudders are not only exclusive to the domain of boating and sailing but are even used in aircrafts and many other conveyances that move through air or water.
HOW DO RUDDERS WORK?
Rudders operate by re-directing the flow of air or water past the hull or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft's stern, tail or after end.
Often rudders are shaped so as to minimize hydrodynamic (for boats) or aerodynamic drag (for aircrafts). On simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be steered by a helmsman. In larger vessels, cables, pushrods and hydraulics may be used to link rudders to steering wheels. The rudder is placed right behind the propellor in these ships. In typical aircraft, pedals operate rudders via mechanical linkages.
INBOARD & OUTBOARD RUDDERS
Boat rudders may be either outboard or inboard. Outboard rudders are hung on the stern or transom. Inboard rudders are hung from a keel or skeg and are thus fully submerged beneath the hull, connected to the steering mechanism by a rudder post which comes up through the hull to deck level, often into a cockpit.
Some sailors use rudder post and mast placement to define the difference between a ketch and a yawl, similar two-masted vessels. Yawls are defined as having the mizzen mast abaft (ie. "aft of") the rudder post; ketches are defined as having the mizzen mast forward of the rudder post.
Small boat rudders that can be steered more or less perpendicular to the hull's longitudinal axis make effective brakes when pushed "hard over." However, terms such as "hard over," "hard to starboard," etc. signify a maximum-rate turn for larger vessels.
A LITTLE ON AIRCRAFT RUDDERS
On an aircraft, the rudder is called a "control surface" along with the rudder-like elevator (attached to horizontal tail structure) and ailerons (attached to the wings) that control pitch and roll. The rudder is usually attached to the fin (or vertical stabilizer) which allows the pilot to control yaw (the side to side movement) in the vertical axis, i.e. change the horizontal direction in which the nose is pointing. The rudder's direction is manipulated with the movement of foot pedals by the pilot.
Nowadays, one gets to see many variations of the rudder and their special purpose for different kinds of ships eg. the Azipod, the Jet Flap rudder, the rotating cylinder rudder etc.
Imagine a car without its steering wheel - an eery proposition and something you definitely wouldnt want to drive. Similarly, it would be impossible to sail without the use of a rudder.
