14. BASIC THEORY 14. 基础理论


Understanding how a Boat Works


理解船的运作原理 How Sails Work 帆是如何运作的


To understand how a sail works, try a simple experiment with a spoon under a running tap.


我们试着做⼀个简单的实验，来了解帆的原理吧！把⼀个勺⼦放在打开的⽔⻰头下。


Hold the spoon lightly by the handle and move the back of the spoon slowly towards the stream of water. You would expect it to be pushed away by the water but actually the spoon is sucked into the flow. The same thing happens when air flows around a sail. The air travelling around the outside (leeward side) of the sail moves faster round the sail than the air on the windward side. This causes a difference in pressure on the two sides of the sail which pulls it to leeward. The force created by the sail acts roughly at right angles to the boom but only part of it drives the boat forward – the rest tries to push it sideways.


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