sail course ® section 9, wind. sail course ® figure 9–1 thermally-induced breezes
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Section 9, Wind
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Figure 9–1 Thermally-induced Breezes
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Figure 9–2 Wind as it Approaches Shore
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Figure 9–4 Sea Breeze
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Figure 9–5 Land Breeze
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Figure 9–6 Boat Wind
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Figure 9–7 Apparent Wind
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Figure 9–8 Close-hauled
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Figure 9–9 True Wind Abeam
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Figure 9–10 Broad Reach
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Figure 9–11 Running
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Figure 9–12 Resolving Wind Forces
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Figure 9–13 Wind Force
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Figure 9–14 Leeway
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Figure 9–15 Effect of Trim
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Figure 9–16 Effect of Heading
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Vocabulary
Apparent Wind. The vector sum of the true wind and the wind created by the movement of the boat. Wind direction and speed as they appear to an observer on a moving boat.
Wake. Water surface turbulence left by a moving boat.
Attached Flow. The movement of particles along a surface, such as the flow of air particles along the leeward side of a sail.
Back. Change in the direction of the wind in a counterclockwise direction in the northern hemisphere and a clockwise direction in the southern hemisphere. See “Veer.”
Boat Wind. The so-called wind produced by the movement of the boat through the water.
Fall Off. To change course so as to bring the relative wind direction farther aft.
Header. A wind that shifts ahead of a boat sailing close-hauled, forcing it to change course to avoid pinching or luffing. Usually a good time to tack.
Puff. A short gust of wind.
Speed Gradient. A marked difference in speed between two adjacent winds.
Vector. A quantity that has both magnitude and direction, commonly represented by an arrow. The length of the arrow represents the magnitude; the direction in which the arrow flies represents the direction in which the quantity acts.
Veer. Change in direction of the wind in a clockwise direction in the Northern Hemisphere and a counterclockwise direction in the Southern Hemisphere. See “Back.”
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End of Section 9 Slides