Why a sailboat can move faster than the wind
OUTRACING THE WIND: Lots of boats can sail faster than the wind... ask a physicist, and she'll say that it's just a question of vectors and relative velocities.
Downwind is easy. If the wind is 10 knots, and the boat makes 6 knots in the same direction, then the crew feels a wind of 4 knots coming over the stern of the boat. The true wind equals the speed of the boat plus the relative wind. As the boat speed approaches the wind speed, the relative wind drops towards zero and so there is no force on the sail. So you can't go faster than the wind.
When the wind is at an angle, we have to add vectors representing these velocities. The faster that the boat goes, the greater the relative wind, the more force there is on the sails, so the greater the force dragging the boat forwards. So the boat accelerates until the drag from the water balances the forward component of the force from the sails. In a fast boat, there's no point going straight downwind: you can never go faster than the wind. So you travel at an angle.
Very interesting!
ReplyDeleteThe wind is one of the reason on why certain sailboat able to move. Well, sailboat might be as fast as the wind only if it uses a motor to move.
ReplyDeleteOld news to anyone who sails, but well explained.
ReplyDeleteYou need to review your source information. It's not the faster a boat goes the more the wind pushes on the sail. It's that when sailing across the path of the wind, the wind will push the boat the same amount at slow speed and at high speed. The boat can then accelerate up to the point where water resistance prevents faster speed (hull speed).
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