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Velocity Made Good
Velocity made good, or VMG, is a term used in sailing, especially in yacht racing, indicating the speed of a sailboat towards (or from) the direction of the wind. The concept is useful because a sailboat cannot sail directly upwind, and thus often can not, or should not, sail directly to a mark to reach it as quickly as possible. It is also often less than optimal to sail directly downwind. Concept Instead of sailing directly toward a windward mark, the helmsman chooses a point of sail towards the direction of the wind that maximizes Velocity Made Good (either towards the destination - or towards better winds). To actually reach a mark, the boat needs to alternate between courses (''tacks'') where the wind approaches from alternating sides. The helmsman uses VMG to find exactly what the optimum angle against the wind is. At the optimum boat speed and angle to the wind, VMG is maximized, steering closer to the direction of the wind will reduce boat speed, while steering further away ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sailing
Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, windsurfer, or kitesurfer), on ''ice'' (iceboat) or on ''land'' (land yacht) over a chosen course, which is often part of a larger plan of navigation. From prehistory until the second half of the 19th century, sailing craft were the primary means of maritime trade and transportation; exploration across the seas and oceans was reliant on sail for anything other than the shortest distances. Naval power in this period used sail to varying degrees depending on the current technology, culminating in the gun-armed sailing warships of the Age of Sail. Sail was slowly replaced by steam as the method of propulsion for ships over the latter part of the 19th century – seeing a gradual improvement in the technology of steam through a number of stepwise developments. Steam allowed scheduled services that ran at higher average speeds than sail ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yacht Racing
Yacht racing is a Sailing (sport), sailing sport involving sailing yachts and larger sailboats, as distinguished from dinghy racing, which involves open boats. It is composed of multiple yachts, in direct competition, racing around a course marked by buoys or other fixed navigational devices or racing longer distances across open water from point-to-point. It can involve a series of races with buoy racing or multiple legs when point-to-point racing. History Yachting, that is, recreational boating, is very old, as exemplified in the ancient poem Catullus 4: The yacht you see there, friends, says that she's been The fastest piece of timber ever seen; She swears that once she could have overhauled All rival boats, whether the challenge called For racing under canvas or with oars. (trans. James Michie) "Yacht" is referred to as deriving from either Norwegian ("jagt"), Middle Low German ("jaght") or from the Dutch word jacht, which means "a swift light vessel of war, commerce or p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helmsman
A helmsman or helm (sometimes driver) is a person who steering, steers a ship, sailboat, submarine, other type of maritime vessel, or spacecraft. The rank and seniority of the helmsman may vary: on small vessels such as fishing vessels and yachts, the functions of the helmsman are combined with that of the skipper (boating), skipper; on larger vessels, there is a separate officer of the watch who is responsible for the safe navigation of the ship and gives orders to the helmsman, who physically steers the ship in accordance with those orders. In the merchant navy, the person at the Ship's wheel, helm is usually an able seaman, particularly during ship arrivals, departures, and while maneuvering in restricted waters or other conditions requiring precise steering. An ordinary seaman is commonly restricted to steering in open waters. Moreover, military ships may have a Seaman (rank), seaman or quartermaster at the helm. A professional helmsman maintains a steady course, properly ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Points Of Sail
A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface. The principal points of sail roughly correspond to 45° segments of a circle, starting with 0° directly into the wind. For many sailing craft 45° on either side of the wind is a ''no-go'' zone, where a sail is unable to mobilize power from the wind. Sailing on a course as close to the wind as possible—approximately 45°—is termed ''beating'', a point of sail when the sails are ''close-hauled''. At 90° off the wind, a craft is on a ''beam reach''. The point of sail between beating and a beam reach is called a ''close reach''. At 135° off the wind, a craft is on a ''broad reach''. At 180° off the wind (sailing in the same direction as the wind), a craft is ''running downwind''. A given point of sail (beating, close reach, beam reach, broad reach, and running downwind) is defined in reference to the true wind—the wind felt by a stationary observe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tack (sailing)
A tack is a nautical term both for the lower, windward corner of a sail and, ''separately'', for the windward side of a sailing craft (side from which the wind is coming while under way—the starboard or port tack. Generally, a boat is on a starboard tack if the wind is coming over the starboard (right) side of boat with sails on port (left) side. Similarly, a boat is on a port tack if the wind is coming over the port (left) side of boat. However, confusion can result when a boat is on a 'run', with the wind coming directly from astern and the mainsail and jib/genoa are on opposite sides of the vessel (wing-on-wing). Therefore, the windward side is defined as the side opposite to that on which the mainsail is being carried. On a starboard tack the mainsail is carried on the port side. On a port tack the mainsail is carried on the starboard side. It is the position of the mainsail that determines the tack. Sail corner The tack is the corner on a fore-and-aft sail where the ''luf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonometry
Trigonometry () is a branch of mathematics that studies relationships between side lengths and angles of triangles. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies. The Greeks focused on the calculation of chords, while mathematicians in India created the earliest-known tables of values for trigonometric ratios (also called trigonometric functions) such as sine. Throughout history, trigonometry has been applied in areas such as geodesy, surveying, celestial mechanics, and navigation. Trigonometry is known for its many identities. These trigonometric identities are commonly used for rewriting trigonometrical expressions with the aim to simplify an expression, to find a more useful form of an expression, or to solve an equation. History Sumerian astronomers studied angle measure, using a division of circles into 360 degrees. They, and later the Babylonians, studied the ratios of the sides of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GPS Navigation Device
A satellite navigation device (satnav device) is a user equipment that uses one or more of several global navigation satellite systems (GNSS) to calculate the device's geographical position and provide navigational advice. Depending on the software used, the satnav device may display the position on a map, as geographic coordinates, or may offer routing directions. As of September 2020, there were four operational GNSS systems, the original United States' Global Positioning System (GPS), the European Union's Galileo, Russia's GLONASS, and China's BeiDou Navigation Satellite System. The Indian Regional Navigation Satellite System (IRNSS) will follow and Japan's Quasi-Zenith Satellite System (QZSS) scheduled for 2023 will augment the accuracy of a number of GNSS. A satellite navigation device can retrieve location and time information from one or more GNSS systems in all weather conditions, anywhere on or near the Earth's surface. Satnav reception requires an unobstructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
