Knock Meaning in Sailing

A knock refers to a sudden wind shift that moves toward the front of the boat, forcing the sailor to turn away from their intended upwind destination. In racing terminology, a knock is the same as a ‘header.’ When a knock occurs, the sails will begin to flap (luff) unless the person at the helm steers the bow further downwind. One specific example involves a racing skipper feeling a knock and realizing they can no longer reach the windward buoy without making an extra turn (tacking). This is often the result of a local weather change or an obstruction like a cliff redirecting the breeze. Understanding how to react to a knock is a core skill for competitive sailing. The opposite of a knock is a ‘lift,’ which allows the boat to point closer to the goal. Experienced sailors watch the water for dark ripples to predict when a knock is coming.