Definition: In the context of mechanical engineering, a "rodder" is a component that helps in controlling or adjusting the movement of an object. The term comes from the Italian word "rider," which means rider on a bicycle. Rudders are particularly useful for boats and other vessels as they help to control the motion of the boat by providing a torque (force) that can be applied to the propeller, thereby changing its speed or direction. They are usually made of wood or metal and