Skeg and rudder

A skeg is a small fin, usually retractable, that drops down from the stern of a kayak into the water to help the hull hold a straight line, particularly in crosswinds that would otherwise push the stern off course. It has no moving steering function; it simply adds resistance at the back of the boat, and the paddler adjusts how far it is dropped depending on wind strength, rather than steering with it directly.

A rudder, by contrast, is a pivoting blade at the stern controlled by foot pedals in the cockpit, letting the paddler actively steer the boat left or right without changing their paddle stroke. Rudders are more common on longer touring and sea kayaks, and some paddlers also use the pedals to help initiate turns in wind or current, beyond just correcting drift.

Neither a skeg nor a rudder is required to paddle a kayak effectively, and plenty of experienced paddlers rely entirely on stroke technique and hull design to track straight and turn. They are best thought of as aids for specific conditions, mainly wind and crosswind, rather than a substitute for learning to read how a hull responds to wind, current, and your own stroke.