What effect does increasing backstay tension have on twist?

• A. Decreases twist
• B. No change
• C. Changes power but not twist
• D. Increases twist

Answer: (D)

Twist is how the angle of the sail changes from the bottom to the top. The backstay runs from the stern to the mast top, and when you tighten it you bend the mast backward. This bending changes the sail’s shape along its height, making the top of the mainsail rotate farther off the centerline relative to the bottom. In other words, the tighter backstay increases twist. Loosening it has the opposite effect, reducing twist. (The vang mainly affects twist by controlling the boom, but the backstay specifically changes mast bend and thus twist.)