Which action would depower sails by adjusting the mainsail and leech upwind?

• A. Mainsheet
• B. Halyard
• C. Downhaul
• D. Outhaul

Answer: (A)

Depowering upwind comes from flattening the mainsail and reducing its power by tightening the leech. The mainsheet is the control that moves the boom, which directly changes the sail’s angle to the wind and how open the leech is. By pulling the mainsheet in, the boom moves toward the centerline, the leech tightens, the sail becomes flatter, and its power decreases.

The other lines affect different parts of the sail: the halyard controls raising and luff tension (not the leech shape), the downhaul primarily tightens the luff to flatten the sail, and the outhaul changes fullness along the foot. None of these adjust the leech upwind as directly as trimming with the mainsheet.