SAIL DRAFT
Sail draft (chord depth) is an imaginary line from luff to leech called the chord. Chord depth can then be expressed as the ratio percentage between the maximum draft (d) and chord length (c). Draft stripes or seams in the sail can be used to estimate the depth. It is quite difficult to measure, so cruising sailors will use their eyes and experience to estimate draft.
DRAFT POSITION
The distance from the luff to where you find the maximum draft in the sail is called the draft position. Draft forward gives a lower lift/drag ratio, and you can’t point as high as with the draft aft. But it is a more forgiving shape, making it easier to steer and giving a wider ‘groove’. The ‘groove’ is a narrow course range determined by a combination of your sail trim, boat speed and pointing ability. Once ‘in the groove’ your boat comes alive and travels at maximum efficiency. Draft forward is therefore more suitable in rougher conditions or for a less experienced helmsman.
Draft aft gives a better lift/drag ratio than draft forward, allowing you to point higher. The sail will, though, stall more easily if the boat is not steered correctly. Draft aft sail shape is therefore best in easier conditions (medium winds and flat seas).
この記事は Yachting Monthly UK の April 2024 版に掲載されています。
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この記事は Yachting Monthly UK の April 2024 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、8,500 以上の雑誌や新聞にアクセスしてください。
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