How do yachts sail faster than the wind

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 feel what happens in a sailboat, put your arm out the window, bent 90 degrees at the elbow, with your palm facing you. Now angle your palm open to the wind very slightly; your arm will move away from you, as the force of lift pulls it sideways. Air traveling on the inside of the sail is moving slower than air traveling around the sail, which creates a pressure difference.

That pressure difference generates lift. The hoist you might feel under your feet when an airplane first takes off is not so different from the jostling sensations of push and drag that sailors feel maneuvering one of these catamarans.

They can sense changes in the forces in the sail and know how to respond to it. The AC72s also use lift when foiling, which is when the two hulls of the catamaran raise off the water and the boat is almost literally flying, with only the rudders and a board anchoring it to the bay. Foiling makes the boat even faster because the drag forces slowing the boat down are now mostly in the air instead of the water. Search-Icon Created with Sketch. KQED is a proud member of. So, what are we doing here at Allen to reduce our impact on the planet?

Posted today at am eSailing Nations Cup champions crowned A huge weekend saw two major tournaments come to a close The eSailing Nations Cup final saw France take on Great Britain in the live virtual final, while the eSailing World Championship featured the ten qualifiers in a winner take all. Posted on 11 Nov. All Rights Reserved. Photographs are copyright by law.