Yourbestsailvideo
Critical angle of attack
19 November 2023 · 17 min · 3K views
What this video covers
Excessive sail trim can cause a sailboat to stall by exceeding the critical angle of attack, a phenomenon where airflow over the sail becomes turbulent and lift collapses.9:22 This angle of attack is defined as the incidence between the sail's chord—the imaginary line connecting the luff and leech—and the apparent wind.1:37 Similar to an airplane wing, a sail generates lift primarily through low pressure on the leeward side.5:28 While an airplane wing typically stalls at 16 to 18 degrees, a sail’s higher camber allows it to maintain laminar flow up to approximately 30 degrees.6:00 Maximum efficiency occurs between 15 and 20 degrees, where the ratio of lift to drag is optimized.11:00 When a sailor over-trims or steers too far off the wind without adjusting the sheets, the angle of attack exceeds this critical threshold, causing the sail to lose drive and the boat to lose speed or control.15:40
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