Sail Course ® Section 10, Sail Shape. Sail Course ® Figure 10–1 Air Flow Around a Sail

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<ul><li>Slide 1</li></ul> <p>Sail Course Section 10, Sail Shape Slide 2 Sail Course Figure 101 Air Flow Around a Sail Slide 3 Sail Course Figure 102 Angle of Attack Slide 4 Sail Course Figure 103 Angle of Attack Held Constant Slide 5 Sail Course Figure 104 Angle of Attack and Streamlines Slide 6 Sail Course Figure 105 Air Flow, Sailing Directly Downwind Slide 7 Sail Course Figure 106 Sail Shape, Draft Slide 8 Sail Course Figure 107 High and Low Aspect Ratio Rigs Slide 9 Sail Course Figure 108 Wind Variation with Height Slide 10 Sail Course Figure 109 Wind Vanes Slide 11 Sail Course Figure 10 10 TelltalesFigure 10 10 Telltales Slide 12 Figure 1011 How Telltales React to Sail Trim Slide 13 Sail Course Vocabulary Aspect Ratio. In general usage, the aspect ratio of a sail is taken to be the length of the luff to the length of the foot. Attached Flow. The movement of particles along a surface, such as the flow of air particles along the leeward side of a sail. Backwinded. A sail is backwinded when another sail to leeward of it is trimmed so closely as to cause increased pressure on the lee side of the windward sail thus causing the windward sail to bulge to windward. Lift. A force generated on the leeward side of a sail by air passing over the airfoil shape. It is the force that drives a sailboat. Also, when sailing close-hauled, a wind that shifts aft to allow a change of course toward the wind direction. Separation. Detachment of air in a smooth laminar flow from the leeward side of a sail. See also Stall. Stall. The condition that arises when the airfoil (sail) or hydrofoil (rudder) is turned too far off and the flow of air or water separates from the foil; there is no longer an attached flow. Slide 14 Sail Course End of Section 10 Slides </p>