Sailing Close to the wind �
Note: If someone sails a boat too close to the wind, they try to sail in the direction from which the wind is blowing, and stop or capsize as a result. See also: close, sail, to, wind. Collins COBUILD Idioms Dictionary, 3rd ed. � HarperCollins Publishers sail close to (or near) the wind. verge on indecency, dishonesty, or disaster. informal. This originated as a nautical expression, meaning �sail as nearly against the wind as is possible�. It has been in figurative use since the mid 19th century. Martin Dove How To Win Any Consumer Competition I like the extra thrill of writing to a. View credits, reviews, tracks and shop for the Vinyl release of "Sailing With The Wind = ������� �����" on Discogs. Boats under sails, Go Nautical, Old Tall Ship, Adventure at Sea, Sunset Sailing, Wooden Ships, Columbia, Gorch Fock, US Coast Guard Barque Eagle. Classic Sailing Ship Wheel Pirate Life Sail Away Set Sail Tall Ships Wooden Boats Belle Photo Sailing Ships. Bessie Ellen's Wheel & Lysefjord cliffs. Sailing close to sheer cliffs in Norway's Lysefjord. Bessie Ellen is a elegant west country trading ketch built in and restored by owner Nikki Alford. If you fancy getting up close to the mountain scenery on a historic ship in Norway this summer have a look at our voyages on Brixham S.

The physics of sailing Sailing gives examples of physics: Newton's laws, vector subtraction, Archimedes' principle and others. This support page from Physclips asks How can a boat sail upwind? How can boats sail faster than the wind? Why are eighteen foot skiffs always sailing upwind? We introduce the physics of sailing to answer these and some other questions. But first: A puzzle. A river runs straight from West to East at 10 knots.

A 10 mile race is held: the boats sail downstream, from West to East. The first heat is held in the morning, when there is no wind. The second heat is held in the afternoon, when there is a 10 knot wind from the West. In which heat are the faster times recorded? Answer below. 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.

The wind is faster than the boat so the air is decelerated by the sails. The sails push backwards against the wind, so the wind pushes forward on the sails. 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. Which is comfortable, but not the most interesting sailing.

You know this force: In a strong wind, it is easier to walk, run or bicycle with the wind pushing on your back. Usually, the wind pushes you in the direction it is going. 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. You just sit there with your sails flapping. This is also not interesting sailing. So let's think about In this diagram, the quantities force and velocity have arrows, because they have a magnitude as well as a direction.

Try this link for an Introduction to vectors. Note that nowhere in this argument did we need to say that the wind was faster than the boat. Now this force is mainly sideways on the boat, and it gets more and more sideways as you get closer to the wind. However, part of the force is forward: the direction we want to go. Why doesn't the boat drift sideways?

Well it does a little, but when it does, the keel , a large nearly flat area under the boat, has to push a lot of water sideways. The water resists this, and exerts the sideways force F k on the keel.

This cancels the sideways component of F w. A little digression: the sideways components of wind and water on the boat make the boat heel tilt away from the wind, as is shown in the diagram below. These two horizontal components have equal size but opposite direction: as forces they cancel, but they make a torque tending to rotate the boat clockwise. This is cancelled by another pair of forces.

The buoyancy and the weight are also equal and opposite, and they make a torque in the opposite direction. As the boat heels to starboard, the lead on the bottom of the keel, which has a substantial fraction of the weight, moves to port and exerts an anticlockwise torque. These two torques cancel. So now back to our question:. Lots of boats can � especially the eighteen footer skiffs on Sydney Harbour. Ask a sailor how, and he'll say "These boats are so fast that they make their own wind", which is actually true.

Ask a physicist, and she'll say that it's just a question of vectors and relative velocities. Downwind diagram at left is easy. If the wind is 10 kt, and the boat makes 6 kt in the same direction, then the crew feels a wind of 4 kt coming over the stern of the boat.

The true wind v w equals the speed of the boat v b plus the relative wind v r. So you can't go faster than the wind. When the wind is at an angle, we have to add the arrows representing these velocities vector addition.

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. Why are eighteen footers always sailing upwind? 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.

But if your boat is fast enough, then the relative wind always seems to be coming mainly from ahead of you, as these arrows show. So the eighteen footers never set ordinary spinnakers: they have asymmetrical sails that they can set even when they are travelling at small angles to the apparent wind.

A good list of links to technical material , courtesy of Sailboat Technology. How can you trim the mainsail using blocks and pulleys to multiply your force? More about hull shapes, bouyancy and sails.

Australian Marine Services Directory has links to weather services, marine services and other information.

Coriolis forces and the reasons behind the major ocean currents and winds. Another puzzle involving relative motion of the air: the plane on the conveyor belt. Did you know that both the special and general theories of relativity are important in the Global Positioning System? See this link from Univ. See where the satellites are at the moment in this animation from J-Track. Details at Science Outreach Centre news and Activities for students and teachers.

Answer to puzzle. The faster heat is the one with no wind. When the wind and the water both move W to E at 10 kt, the boats drift down the river at 10 kt, with their sails hanging limp.

In the heat with no wind as measured on the land , a drifting boat has a headwind of 10 kt. You can tack into that. Of course, you don't get something for nothing. In the heat with wind, the river does very little work on the boat. In the heat without wind, it exerts much greater force on the boat, in particular on the keel or centreboard. Much of that work goes into disturbing the air downwind of the boat's sails. The man in the photo at right did a lot of sailing on rivers: he would have known that.

Modified 10 Jan 03 J. Wolfe unsw. Joe's scientific home page Joe's educational pages Joe's music page. An experiment. Here is what my left hand looks like as I bicycle, signalling a left turn. If my hand is flat and horizontal, I just feel the drag force of the wind acting backwards. But if I tilt my hand up a little at the front, I feel lift force as well: the force on my hand is both upwards and backwards.

The arrows show the wind speed relative to me. To get past my hand, the wind is deflected down, and this pushes my hand up as well as back. Sailing close to the wind uses the shape of the sails to generate lift.

To flow around the sails, the wind has to deviate in direction, as shown by the arrows for initial velocity v i and final velocity v f , which are given with respect to the boat. The change of velocity dv is in the direction shown. The force F w that the wind exerts on the sails is in the opposite direction. There is also a Bernoulli effect , which contributes in a secondary way.

Make point:

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