The rudder is turned side to side by the tiller, the long metal arm seen here extending from the top of the rudder about 3 feet into the cockpit. On many boats the tiller is made of wood.
Note the black handle on top of the metal tiller arm. Called a tiller extension, this device mounts near the end of the tiller and can be moved far out to the side of the boat or forward. The extension is needed because when sailing close to the wind, sailors may need to move their body weight far out to the side (called “hiking out”) in order to keep the boat balanced. We’ll see this in Part 3 of this course.)
Most large sailboats use a wheel apparatus to turn the rudder, because the forces on the boat’s rudder can be so much larger that it would be difficult to steer with a tiller.