What is the primary function of a rudder on a boat?

The primary function of a rudder on a boat is to provide steering control. When the rudder is turned, it alters the flow of water past the hull, allowing the boat to change direction. This steering mechanism is essential for navigating and maintaining a desired course. Unlike propulsion, which is achieved through engines or sails, the rudder's role is purely about guiding the boat, making it a critical component for maneuverability on the water.

While options like providing propulsion or supporting sails pertain to other parts of the vessel, the rudder serves specifically to influence the direction the boat is moving in, thereby enhancing control and safety while navigating. Similarly, anchoring a boat involves different instruments, such as an anchor, that serve a distinct purpose.