Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the water, on ice (iceboat) or on land over a chosen course, which is often part of a larger plan of navigation.
Wind-chill or windchill is the lowering of body temperature due to the passing-flow of lower-temperature air.
The Tornado is a double handed multihull class recognised as an International Class by the International Sailing Federation. It was used for the Catamaran discipline at the Olympic Games from 1976 to 2008.
A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface.
A spinnaker is a sail designed specifically for sailing off the wind from a reaching course to a downwind, i.e. with the wind 90–180° off bow. The spinnaker fills with wind and balloons out in front of the boat when it is deployed, called flying. It is constructed of lightweight fabric, usually nylon, and is often brightly coloured. It may be optimised for a particular range of wind angles, as either a reaching or a running spinnaker, by the shaping of the panels and seams.
Running rigging is the rigging of a sailing vessel that is used for raising, lowering, shaping and controlling the sails on a sailing vessel—as opposed to the standing rigging, which supports the mast and bowsprit. Running rigging varies between vessels that are rigged fore and aft and those that are square-rigged.
Sail components include the features that define a sail's shape and function, plus its constituent parts from which it is manufactured. A sail may be classified in a variety of ways, including by its orientation to the vessel and its shape,. Sails are typically constructed out of flexible material that is shaped by various means, while in use, to offer an appropriate airfoil, according to the strength and apparent direction of the wind. A variety of features and fittings allow the sail to be attached to lines and spars.
A sailboat broaches when its heading suddenly changes towards the wind due to wind/sail interactions for which the rudder cannot compensate. This happens when the aerodynamic force on the rig greatly exceeds the hydrodynamic force on the hull, due to a sudden increase in wind strength or turbulent sea conditions. In small boats and dinghies, broaching can lead to a death roll. In larger boats broaching can lay the mast horizontal, putting both rig and crew at risk. It can be particularly dangerous when racing other boats at close quarters.
In a keel boat, a death roll is the act of broaching to windward, putting the spinnaker pole into the water and causing a crash-jibe of the boom and mainsail, which sweep across the deck and plunge down into the water. The death roll often results in destruction of the spinnaker pole and sometimes even dismasting of the boat. Serious injury to crew is possible due to the swift and uncontrolled action of the boom and associated gear sweeping across the boat and crashing to the (now) leeward side.
The P-Class is a type of small single sail dinghy, popular as a training boat for young people in New Zealand. This class is famous for being the sailing trainer vessel for many new entrants into the sport, and virtually every famous New Zealand yachtsman, including Sir Peter Blake and Russell Coutts, learnt to sail in one. The P-Class was for many years the most common sailing boat in New Zealand.
Wind direction is reported by the direction from which it originates. For example, a northerly wind blows from the north to the south. Wind direction is usually reported in cardinal directions or in azimuth degrees. Wind direction is measured in degrees clockwise from due north. Consequently, a wind blowing from the north has a wind direction of 0°; a wind blowing from the east has a wind direction of 90°; a wind blowing from the south has a wind direction of 180°; and a wind blowing from the west has a wind direction of 270°. In general, wind directions are measured in units from 0° to 360°, but can alternatively be expressed from -180° to 180°.
A wingsail is a variable-camber aerodynamic structure that is fitted to a marine vessel in place of conventional sails. Wingsails are analogous to airplane wings, except that they are designed to provide lift on either side to accommodate being on either tack. Whereas wings adjust camber with flaps, wingsails adjust camber with a flexible or jointed structure. Wingsails are typically mounted on an unstayed spar—often made of carbon fiber for lightness and strength. The geometry of wingsails provides more lift, and a better lift-to-drag ratio, than traditional sails. Wingsails are more complex and expensive than conventional sails.
An asymmetrical spinnaker is a sail used when sailing downwind. Also known as an "asym" or "aspin", it can be described as a cross between a genoa jib and a spinnaker. It is asymmetric like a genoa, but, the asymmetrical spinnaker is not attached to the forestay over the full length of its luff, being rigged like a spinnaker. The asymmetrical spinnaker has a larger camber than a genoa, making it optimal for generating lift at larger angles of attack, but the camber is significantly less than that of a spinnaker.
Wind-powered vehicles derive their power from sails, kites or rotors and ride on wheels—which may be linked to a wind-powered rotor—or runners. Whether powered by sail, kite or rotor, these vehicles share a common trait: As the vehicle increases in speed, the advancing airfoil encounters an increasing apparent wind at an angle of attack that is increasingly smaller. At the same time, such vehicles are subject to relatively low forward resistance, compared with traditional sailing craft. As a result, such vehicles are often capable of speeds exceeding that of the wind.
USA-17 is a sloop rigged racing trimaran built by the American sailing team BMW Oracle Racing to challenge for the 2010 America's Cup. Designed by VPLP Yacht Design with consultation from Franck Cammas and his Groupama multi-hull sailing team, BOR90 is very light for her size being constructed almost entirely out of carbon fiber and epoxy resin, and exhibits very high performance being able to sail at 2.0 to 2.5 times the true wind speed. From the actual performance of the boat during the 2010 America's Cup races, it can be seen that she could achieve a velocity made good upwind of over twice the wind speed and downwind of over 2.5 times the wind speed. She can apparently sail at 20 degrees off the apparent wind. The boat sails so fast downwind that the apparent wind she generates is only 5-6 degrees different from that when she is racing upwind; that is, the boat is always sailing upwind with respect to the apparent wind. An explanation of this phenomenon can be found in the article on sailing faster than the wind.
High-performance sailing is achieved with low forward surface resistance—encountered by catamarans, sailing hydrofoils, iceboats or land sailing craft—as the sailing craft obtains motive power with its sails or aerofoils at speeds that are often faster than the wind.
Forces on sails result from movement of air that interacts with sails and gives them motive power for sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and sail-powered land vehicles. Similar principles in a rotating frame of reference apply to wind mill sails and wind turbine blades, which are also wind-driven. They are differentiated from forces on wings, and propeller blades, the actions of which are not adjusted to the wind. Kites also power certain sailing craft, but do not employ a mast to support the airfoil and are beyond the scope of this article.
De Nijlânnermolen is a smock mill in Workum, Friesland, Netherlands. It has been restored to working order and is designated as a reserve mill. It is listed as a Rijksmonument.
