How does the rudder work?
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.
The rudder is the small moving section at the rear of the stabilizer that is attached to the fixed sections by hinges. Because the rudder moves, it varies the amount of force generated by the tail surface and is used to generate and control the yawing motion of the aircraft.
The rudder moves in the direction of lower pressure. As the rudder goes, so goes the stern, and the boat turns. During turns the boat pivots around a point near its midsection—roughly at the mast on a sloop. The stern moves one way, the bow moves the other way, as the boat changes direction.
A rudder is one of the most important components in any marine vessel. It enables the helmsman to steer, control, and direct the ship in the sea. A damaged rudder poses a high risk to the structural integrity of the ship. Without an efficient rudder, a ship can't operate properly, even with all other systems intact.
The rudder is controlled by the left and right rudder pedals. When the rudder is deflected into the airflow, a horizontal force is exerted in the opposite direction. [Figure 6-15] By pushing the left pedal, the rudder moves left.
The rudder of an airplane is the control surface of the aircraft that changes its direction on the vertical axis. However, it is not meant to turn the aircraft alone. In fact, one of its main functions is to keep the stability of an airplane after an airplane turns using ailerons.
Without the rudder the aircraft can still be controlled using ailerons. The tail-plane helps provide stability and the elevator controls the 'pitch' of the aircraft (up and down). Without these the aircraft cannot be controlled.
Very short answer: Yes, you can turn an airplane without using rudder input. Simply rolling the airplane to an appropriate bank angle, combined with applying aft stick pressure to maintain altitude, will cause an airplane to turn.
If you press the right rudder pedal, the rudder will deflect to the right (starboard) side of the plane. The tail will yaw (clockwise) around to the left (port) side of the Center of Gravity. The nose will subsequently yaw (clockwise) around to the right side of the CoG.
The rudder moment turning the ship is created by the transverse force on the rudder and an oppositely acting transverse force on the ship hull acting near the bow. This moment increases with distance between the rudder force and the hull force.
How rudder is locked?
Rudder lock occurs when the force on a deflected rudder (in a steady sideslip) suddenly reverses as the vertical stabilizer stalls. This may leave the rudder stuck at full deflection with the pilot unable to recenter it.
Losing the Rudder
If the rudder breaks or falls off, the boat will round up, so you'll be more or less head to wind with everything flapping. First, get the sails situated and then start devising alternate steering methods. Some boats carry emergency rudders, but most likely you'll be devising a makeshift rudder.

noun. rud·der ˈrə-dər. : an underwater blade that is positioned at the stern of a boat or ship and controlled by its helm and that when turned causes the vessel's head to turn in the same direction.
The rudder pedals are connected together in a way where if you push one forward, the other pedal moves back. When both pedals are in the center position, the aircraft's rudder will be straight. When you push the right rudder pedal forward, the rudder deflects to the right, which causes the aircraft to yaw to the right.
Flight at minimum controllable airspeed, or slow flight, is an excellent exercise for improving rudder coordination. As the airplane slows in level flight the wing's angle of attack increases. The volume of air blowing past the rudder decreases, meaning you need more and more rudder to maintain coordinated flight.
To fly the wing-low method, you use your rudder to line your nose up with the runway, and ailerons to correct for left/right drift all the way from final approach to touchdown. Essentially, you're slipping the plane through the crosswind in order to keep yourself lined up with the runway from final to touchdown.
A pilot can turn the airplane to the right and the left, the motion we call yaw, without using ailerons, but he/she will quickly lose control. Ailerons help with another important control on the airplane: roll.
Why is the rudder always turned when I see planes on the ground? When an aircraft is parked in its parking position, the engines are usually turned off. Therefore, the airplane looses all its hydraulic pressure needed to move the flight control surfaces.
In most aircraft, the rudder is controlled through the flight deck rudder pedals which are linked mechanically to the rudder. Deflection of a rudder pedal causes a corresponding rudder deflection in the same direction; that is, pushing the left rudder pedal will result in a rudder deflection to the left.
However, as noted above, the rudder is most often used to align the aircraft during takeoff and landing with the runway during crosswinds.
Can a plane fly without tail?
Tailless aircraft have been flown since the pioneer days; the first stable aeroplane to fly was the tailless Dunne D. 5, in 1910. The most successful tailless configuration has been the tailless delta, especially for combat aircraft, though the most familiar tailless delta is the Concorde airliner.
Yes, they can, these are called lifting body aircraft. They maintain directional stability using the control surfaces near the tail.
Why You Need So Much Right Rudder. The four left-turning tendencies create the forces that make your airplane veer left during takeoff. Step on the right rudder to cancel them out, and you'll maintain a perfect centerline throughout your takeoff roll.
Flight Controls and Their Purposes
Pitch moves the nose up and down. The ailerons move the airplane around the longitudinal axis (nose to tail), a motion called roll. And finally, the rudder controls the plane around the vertical axis (up and down), which is called yaw.
A rudder goes maximum 35 degree on either side in merchant vessel. Its a regulation that rudder should come from 35 from one side to 30 degree on another side within 28 seconds.