You just sit there with your sails flapping. Sailing directly upwind (exactly anti-parallel to the wind, like the boat at right) is also easy to understand: it's impossible ( impossible with sails: a boat with a wind turbine driving a propellor could go directly upwind. Usually, the wind pushes you in the direction it is going. You know this force: In a strong wind, it is easier to walk, run or bicycle with the wind pushing on your back. Which is comfortable, but not the most interesting sailing. But for a boat with normal sails, the catch is that, downwind, you can only ever sail more slowly than the wind, even with a spinnaker. The sails push backwards against the wind, so the wind pushes forward on the sails. The wind is faster than the boat so the air is decelerated by the sails. Sailing downwind (parallel to the wind, like the boat at left) is easy to understand: the wind blows into the sails and pushes against them. In which heat are the faster times recorded? The second heat is held in the afternoon, when there is a 10 knot wind from the West. The first heat is held in the morning, when there is no wind. A 10 mile race is held: the boats sail downstream, from West to East. But first:Ī river runs straight from West to East at 10 knots. We introduce the physics of sailing to answer these and some other questions. Why are eighteen foot skiffs always sailing upwind?.

How can boats sail faster than the wind?.Sailing gives examples of physics: Newton's laws, vector subtraction, Archimedes' principle and others.

Eastward catamaran