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True wind (V T) is the same everywhere in the diagram, whereas boat velocity (V B) and apparent wind (V A) vary with point of sail. 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.
A polar diagram, or polar plot, is a graph that shows a sailboat's potential speed over a range of wind speeds and relative wind angles. [1] It normally consists of the right side of a line chart with the radius representing the yacht speed and the angle representing the wind direction blowing from top to bottom. Several lines are normally ...
Marine currents can carry large amounts of water, largely driven by the tides, which are a consequence of the gravitational effects of the planetary motion of the Earth, the Moon and the Sun. Augmented flow velocities can be found where the underwater topography in straits between islands and the mainland or in shallows around headlands plays a major role in enhancing the flow velocities ...
Lots of different technology variants have been tested, and there has not been convergence on a predominant typology. Most have been horizontal-axis, like wind turbines, but with 2, 3, or more blades and either mounted on a seabed fixed foundation or on a floating platform. In addition, vertical-axis turbines and tidal kites are also being ...
Diagram contrasting course made good to windward by tacking a schooner versus a square-rigged ship. Sailing vessels cannot sail directly into the wind. Instead, square-riggers must sail a course that is between 60° and 70° away from the wind direction [76] and fore-and aft vessels can typically sail no closer than 45°. [77]
Boat velocity (in black) generates an equal and opposite apparent wind component (not shown), which adds to the true wind to become apparent wind. Apparent wind and forces on a sailboat . As the boat sails further from the wind, the apparent wind becomes smaller and the lateral component becomes less; boat speed is highest on the beam reach.
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 ...
Wind-assisted propulsion is the practice of decreasing the fuel consumption of a merchant vessel through the use of sails or some other wind capture device. Sails used to be the primary means of propelling ships , but with the advent of the steam engine and the diesel engine , sails came to be used for recreational sailing only.