Wind and Tide

1. Peter Bentley Technical Projects Manager Skandia Team GBR Wind and Tide

2. You don't need a weather man To know which way the wind blows Bob Dylan Subterranean Homesick Blues Wind and Tide

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6. Sailing in tide - • Which way does the wind blow? • Solutions: • Trigonometry • Vectors Wind and Tide

7. Solutions: • Trigonometry • Vectors Wind and Tide

8. Vectors • Vectors are easy! • The length of the line represents the magnitude of the action – speed of wind, tide, boat etc. • The angle of the line represents the direction the wind, boat, tide etc. is moving. • If we draw the lines so they touch at the ends, we can ‘add’ the vectors Wind and Tide

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22. Downwind: • Which way does the wind blow? • Where shall we put the mark? Wind and Tide

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30. Windward-Leeward Courses • Using just two buoys you can’s set a perfect beat and a perfect run in a cross-tide situation Wind and Tide

31. Windward-Leeward Courses • Using just two buoys you can’s set a perfect beat and a perfect run in a cross-tide situation • Compromise • In all but the most extreme situations it is possible to produce a good compromise Wind and Tide

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34. Summary so far…. Wind and Tide

35. Sailing Wind • The Sailing Wind is that experienced by a free-floating stationary boat Wind and Tide

36. Sailing Wind • The Sailing Wind is that experienced by a free-floating stationary boat • Upwind • The Sailing Wind is always influenced by the tide • The COG and SOG is always influenced by the tide • The two effects are additive Wind and Tide

37. Sailing Wind • The Sailing Wind is that experienced by a free-floating stationary boat • Upwind • The Sailing Wind is always influenced by the tide • The COG and SOG is always influenced by the tide • The two effects are additive • Downwind • The Sailing Wind is always influenced by the tide • The COG and SOG is always influenced by the tide • The two effects are subtractive Wind and Tide

38. Startlines • Unbiased starting lines are set at 90 degrees • to the sailing wind Wind and Tide

39. Startlines • Unbiased starting lines are set at 90 degrees • to the sailing wind • Course Axis • Unbiased legs are set based on VMG with equal time on each tack Wind and Tide

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41. What can go wrong? Wind and Tide

42. The Naive Race Officer Wind and Tide

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44. The Very Naive Race Officer • I’m not suggesting any of you would do this….. But • If using our original scenario, we put the windward mark directly upwind of the committee boat using a wind reference from the Committee boat (Ground Wind) • 60 seconds on long tack • Time on short tack a) 40 seconds • b) 22 seconds • c) 17 seconds Wind and Tide

45. The Very Naive Race Officer • I’m not suggesting any of you would do this….. But • If using our original scenario, we put the windward mark directly upwind of the committee boat using a wind reference from the Committee boat (Ground Wind) • 60 seconds on long tack • Time on short tack • c) 17 seconds Wind and Tide

46. Vector Changes Wind and Tide

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