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French Aviso Premier-Maître L'Her (F792)
''Premier-Maître L'Her'' (F792) is a in the French Navy. Design The aviso has a crew of 90 sailors, and vessels of this class have the reputation of being among the most difficult in bad weather. Their high windage makes them particularly sensitive to pitch and roll as soon as the sea is formed. Their armament, consequent for a vessel of this tonnage, allows them to manage a large spectrum of missions. During the Cold War, they were primarily used to patrol the continental shelf of the Atlantic Ocean in search of Soviet Navy submarines. Due to the poor performance of the hull sonar, as soon as an echo appeared, the reinforcement of an ASM frigate was necessary to chase it using its towed variable depth sonar. Their role as patrollers now consists mainly of patrols and assistance missions, as well as participation in UN missions (blockades, flag checks) or similar marine policing tasks (fight against drugs, extraction of nationals, fisheries control, etc.). The mer-mer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windage
Windage is a term used in aerodynamics, firearms ballistics, and automobiles. Usage Aerodynamics Windage is a force created on an object by friction when there is relative movement between air and the object. Windage loss is the reduction in efficiency due to windage forces. For example, electric motors are affected by friction between the rotor and air. Large alternators have significant losses due to windage. To reduce losses, hydrogen gas may be used, since it is less dense. There are two causes of windage: # The object is moving and being slowed by resistance from the air. # A wind is blowing, producing a force on the object. The term can refer to: * The effect of the force, for example the deflection of a missile or an aircraft by a cross wind. * The area and shape of the object that make it susceptible to friction, for example those parts of a boat that are exposed to the wind. Aerodynamic streamlining can be used to reduce windage. There is a hydrodynamic effect si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gulf Of Aden
The Gulf of Aden ( ar, خليج عدن, so, Gacanka Cadmeed 𐒅𐒖𐒐𐒕𐒌 𐒋𐒖𐒆𐒗𐒒) is a deepwater gulf of the Indian Ocean between Yemen to the north, the Arabian Sea to the east, Djibouti to the west, and the Guardafui Channel, Socotra and Somalia to the south. In the northwest, it connects with the Red Sea through the Bab-el-Mandeb strait, and it connects with the Arabian Sea to the east. To the west, it narrows into the Gulf of Tadjoura in Djibouti. The ancient Greeks regarded the gulf as one of the most important parts of the Erythraean Sea. It later came to be dominated by Muslims, as the area around the gulf converted to Islam. From the late 1960s onwards, there started to be an increased Soviet naval presence in the Gulf. The importance of the Gulf of Aden declined when the Suez Canal was closed, but it was revitalized when the canal was reopened in 1975, after being deepened and widened by the Egyptian government. The waterway is part of the importa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operation Atalanta
Operation Atalanta, formally European Union Naval Force (EU NAVFOR) Somalia, is a current counter-piracy military operation at sea off the Horn of Africa and in the Western Indian Ocean, that is the first naval operation conducted by the European Union (EU). The operational headquarters is currently located at the Spanish Operation Headquarters (ESOHQ) at Naval Station Rota (NAVSTA Rota) in Spain, having moved from London as a result of the British withdrawal from the EU. It is part of a larger global action by the EU to prevent and combat acts of piracy in the Indian Ocean, and it is the first EU naval operation to be launched. It cooperates with the multinational Combined Task Force 151 of the US-led Combined Maritime Forces (CMF) and NATO's anti-piracy Operation Ocean Shield. The mission was launched in December 2008 with a focus on protecting Somalia-bound vessels and shipments belonging to the WFP and AMISOM, as well as select other vulnerable shipments. In addition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ship Commissioning
Ship commissioning is the act or ceremony of placing a ship in active service and may be regarded as a particular application of the general concepts and practices of project commissioning. The term is most commonly applied to placing a warship in active duty with its country's military forces. The ceremonies involved are often rooted in centuries-old naval tradition. Ship naming and launching endow a ship hull with her identity, but many milestones remain before she is completed and considered ready to be designated a commissioned ship. The engineering plant, weapon and electronic systems, galley, and other equipment required to transform the new hull into an operating and habitable warship are installed and tested. The prospective commanding officer, ship's officers, the petty officers, and seamen who will form the crew report for training and familiarization with their new ship. Before commissioning, the new ship undergoes sea trials to identify any deficiencies needing corre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ship Naming And Launching
Ceremonial ship launching involves the performance of ceremonies associated with the process of transferring a vessel to the water. It is a nautical tradition in many cultures, dating back thousands of years, to accompany the physical process with ceremonies which have been observed as public celebration and a solemn blessing, usually but not always, in association with the launch itself. Ship launching imposes stresses on the ship not met during normal operation and, in addition to the size and weight of the vessel, represents a considerable engineering challenge as well as a public spectacle. The process also involves many traditions intended to invite good luck, such as christening by breaking a sacrificial bottle of champagne over the bow as the ship is named aloud and launched. Methods There are three principal methods of conveying a new ship from building site to water, only two of which are called "launching". The oldest, most familiar, and most widely used is th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keel Laying
Laying the keel or laying down is the formal recognition of the start of a ship's construction. It is often marked with a ceremony attended by dignitaries from the shipbuilding company and the ultimate owners of the ship. Keel laying is one of the four specially celebrated events in the life of a ship; the others are launching, commissioning and decommissioning. In earlier times, the event recognized as the keel laying was the initial placement of the central timber making up the backbone of a vessel, called the keel. As steel ships replaced wooden ones, the central timber gave way to a central steel beam. Modern ships are most commonly built in a series of pre-fabricated, complete hull sections rather than around a single keel. The event recognized as the keel laying is the first joining of modular components, or the lowering of the first module into place in the building dock. It is now often called "keel authentication", and is the ceremonial beginning of the ship's life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
French Franc
The franc (, ; sign: F or Fr), also commonly distinguished as the (FF), was a currency of France. Between 1360 and 1641, it was the name of coins worth 1 livre tournois and it remained in common parlance as a term for this amount of money. It was reintroduced (in decimal form) in 1795. After two centuries of inflation, it was redenominated in 1960, with each (NF) being worth 100 old francs. The NF designation was continued for a few years before the currency returned to being simply the franc. Many French residents, though, continued to quote prices of especially expensive items in terms of the old franc (equivalent to the new centime), up to and even after the introduction of the euro (for coins and banknotes) in 2002. The French franc was a commonly held international reserve currency of reference in the 19th and 20th centuries. Between 1998 and 2002, the conversion of francs to euros was carried out at a rate of 6.55957 francs to 1 euro. History The French Franc tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United Nations
The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmonizing the actions of nations. It is the world's largest and most familiar international organization. The UN is headquarters of the United Nations, headquartered on extraterritoriality, international territory in New York City, and has other main offices in United Nations Office at Geneva, Geneva, United Nations Office at Nairobi, Nairobi, United Nations Office at Vienna, Vienna, and Peace Palace, The Hague (home to the International Court of Justice). The UN was established after World War II with Dumbarton Oaks Conference, the aim of preventing future world wars, succeeding the League of Nations, which was characterized as ineffective. On 25 April 1945, 50 governments met in San Francisco for United Nations Conference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Depth Sonar
A towed array sonar is a system of hydrophones towed behind a submarine or a surface ship on a cable. Trailing the hydrophones behind the vessel, on a cable that can be kilometers long, keeps the array's sensors away from the ship's own noise sources, greatly improving its signal-to-noise ratio, and hence the effectiveness of detecting and tracking faint contacts, such as quiet, low noise-emitting submarine threats, or seismic signals. A towed array offers superior resolution and range compared with hull mounted sonar. It also covers the baffles, the blind spot of hull mounted sonar. However, effective use of the system limits a vessel's speed and care must be taken to protect the cable from damage. History During World War I, a towed sonar array known as the "Electric Eel" was developed by Harvey Hayes, a U.S. Navy physicist. This system is believed to be the first towed sonar array design. It employed two cables, each with a dozen hydrophones attached. The project was discontin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: ''passive'' sonar means listening for the sound made by vessels; ''active'' sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and SODAR (an upward-looking in-air sonar) is used for atmospheric investigations. The term ''sonar'' is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine
A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely operated vehicles and Autonomous underwater vehicle, robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as ''boats'' rather than ''ships'' irrespective of their size. Although experimental submarines had been built earlier, submarine design took off during the 19th century, and they were adopted by several navies. They were first widely used during World War I (1914–1918), and are now used in many navy, navies, large and small. Military uses include attacking enemy surface ships (merchant and military) or other submarines, and for aircraft carrier protection, Blockade runner, blockade running, Ballistic missile submarine, nuclear deterrence, reconnaissance, conventio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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