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Minehunter
A minehunter is a naval vessel that seeks, detects, and destroys individual naval mines. Minesweepers, on the other hand, clear mined areas as a whole, without prior detection of mines. A vessel that combines both of these roles is known as a mine countermeasures vessel (MCMV). Description A minehunter uses an imaging sonar to detect and classify targets and then sends out divers or remotely operated vehicles (ROVs) to inspect and neutralise the threat, often using small charges that are detonated remotely. As minehunters will often be operating in close proximity to mines, they are designed so as to reduce their own acoustic and magnetic signatures, two common forms of trigger for mines. For example, they are often soundproofed by mounting machinery on shock absorbers or by using quiet electrical drive, low magnetic electric motors and usually have a wood, fiberglass or non-ferrous metal hull, or are degaussed to reduce magnetic signature.Design Guide and Req ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minesweeper
A minesweeper is a small warship designed to remove or detonate naval mines. Using various mechanisms intended to counter the threat posed by naval mines, minesweepers keep waterways clear for safe shipping. History The earliest known usage of the naval mine dates to the Ming dynasty.Needham, Volume 5, Part 7, 203–205. Dedicated minesweepers, however, only appeared many centuries later during the Crimean War, when they were deployed by the British. The Crimean War minesweepers were rowboats trailing Grappling hook, grapnels to snag mines. Minesweeping technology picked up in the Russo-Japanese War, using aging torpedo boats as minesweepers. In Britain, naval leaders recognized before the outbreak of World War I that the development of sea mines was a threat to the nation's shipping and began efforts to counter the threat. Sir Arthur Wilson, 3rd Baronet, Sir Arthur Wilson noted the real threat of the time was a blockade aided by mines and not an invasion. The function of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naval Mine
A naval mine is a self-contained explosive weapon placed in water to damage or destroy surface ships or submarines. Similar to anti-personnel mine, anti-personnel and other land mines, and unlike purpose launched naval depth charges, they are deposited and left to wait until, depending on their fuzing, they are triggered by the approach of or contact with any vessel. Naval mines can be used offensively, to hamper enemy shipping movements or lock vessels into a harbour; or defensively, to create "safe" zones protecting friendly sea lanes, harbours, and naval assets. Mines allow the minelaying force commander to concentrate warships or defensive assets in mine-free areas giving the adversary three choices: undertake a resource-intensive and time-consuming minesweeping effort, accept the casualties of challenging the minefield, or use the unmined waters where the greatest concentration of enemy firepower will be encountered. Although international law requires signatory nations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minesweeper
A minesweeper is a small warship designed to remove or detonate naval mines. Using various mechanisms intended to counter the threat posed by naval mines, minesweepers keep waterways clear for safe shipping. History The earliest known usage of the naval mine dates to the Ming dynasty.Needham, Volume 5, Part 7, 203–205. Dedicated minesweepers, however, only appeared many centuries later during the Crimean War, when they were deployed by the British. The Crimean War minesweepers were rowboats trailing Grappling hook, grapnels to snag mines. Minesweeping technology picked up in the Russo-Japanese War, using aging torpedo boats as minesweepers. In Britain, naval leaders recognized before the outbreak of World War I that the development of sea mines was a threat to the nation's shipping and began efforts to counter the threat. Sir Arthur Wilson, 3rd Baronet, Sir Arthur Wilson noted the real threat of the time was a blockade aided by mines and not an invasion. The function of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mine Countermeasures Vessel
A mine countermeasures vessel or MCMV is a type of naval ship designed for the location of and destruction of naval mine A naval mine is a self-contained explosive weapon placed in water to damage or destroy surface ships or submarines. Similar to anti-personnel mine, anti-personnel and other land mines, and unlike purpose launched naval depth charges, they are ...s which combines the role of a minesweeper and minehunter in one hull. The term MCMV is also applied collectively to minehunters and minesweepers. Most modern MCMVs are designed to locate, identify, and neutralize or remove underwater mines. Any explosive device that is placed in or near water to damage or destroy ships, submarines, or other naval vessels is classified as a mine. They can pose a significant threat to naval operations, maritime trade, and coastal security. The primary purpose of a MCMV is to ensure safe passage for friendly naval and commercial vessels by clearing waterways, harbors, and shippin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voith-Schneider
A cyclorotor, cycloidal rotor, cycloidal propeller or cyclogiro, is a fluid propulsion device that converts shaft power into the acceleration of a fluid using a rotating axis perpendicular to the direction of fluid motion. It uses several blades with a spanwise axis parallel to the axis of rotation and perpendicular to the direction of fluid motion. These blades are cyclically pitched twice per revolution to produce force (thrust or lift) in any direction normal to the axis of rotation. Cyclorotors are used for propulsion, lift, and control on air and water vehicles. An aircraft using cyclorotors as the primary source of lift, propulsion, and control is known as a cyclogyro or cyclocopter. A unique aspect is that it can change the magnitude and direction of thrust without the need of tilting any aircraft structures. The patented application, used on ships with particular actuation mechanisms both mechanical or hydraulic, is a Voith Schneider Propeller. Operating principle The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degaussing
Degaussing, or deperming, is the process of decreasing or eliminating a remnant magnetic field. It is named after the gauss, a unit of magnetism, which in turn was named after Carl Friedrich Gauss. Due to magnetic hysteresis, it is generally not possible to reduce a magnetic field completely to zero, so degaussing typically induces a very small "known" field referred to as bias. Degaussing was originally applied to reduce ships' magnetic signatures during World War II. Degaussing is also used to reduce magnetic fields in tape recorders and cathode-ray tube displays, and to destroy data held on magnetic storage. Ships' hulls The term was first used by then-Commander Charles F. Goodeve, Royal Canadian Naval Volunteer Reserve, during World War II while trying to counter the German magnetic naval mines that were wreaking havoc on the British fleet. The mines detected the increase in the magnetic field when the steel in a ship concentrated the Earth's magnetic field over it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Draft (hull)
The draft or draught of a ship is a determined depth of the vessel below the waterline, measured vertically to its hull's lowest—its propellers, or keel, or other reference point. Draft varies according to the loaded condition of the ship. A deeper draft means the ship will have greater vertical depth below the waterline. Draft is used in under keel clearance calculations, where the draft is calculated with the available depth of water (from Electronic navigational charts) to ensure the ship can navigate safely, without grounding. Navigators can determine their draught by calculation or by visual observation (of the ship's painted load lines). Related terminology A ship's draft/draught is the "depth of the vessel below the waterline measured vertically to the lowest part of the hull, propellers, or other reference point". That is, the draft or draught is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shipping Channel
In physical geography and hydrology, a channel is a landform on which a relatively narrow body of water is situated, such as a river, river delta or strait. While ''channel'' typically refers to a natural formation, the cognate term ''canal'' denotes a similar artificial structure. Channels are important for the functionality of ports and other bodies of water used for navigability for shipping. Naturally, channels will change their depth and capacity due to erosion and deposition processes. Humans maintain navigable channels by dredging and other engineering processes. By extension, the term also applies to fluids other than water, e.g., lava channels. The term is also traditionally used to describe the waterless surface features on Venus. Formation Channel initiation refers to the site on a mountain slope where water begins to flow between identifiable banks.Bierman, R. B, David R. Montgomery (2014). Key Concepts in Geomorphology. W. H. Freeman and Company Publishers. Un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harbour
A harbor (American English), or harbour (Commonwealth English; see American and British English spelling differences#-our, -or, spelling differences), is a sheltered body of water where ships, boats, and barges can be Mooring, moored. The term ''harbor'' is often used interchangeably with ''port'', which is a man-made facility built for loading and unloading Watercraft, vessels and dropping off and picking up passengers. Harbors usually include one or more ports. Alexandria Port in Egypt, meanwhile, is an example of a port with two harbors. Harbors may be natural or artificial. An artificial harbor can have deliberately constructed breakwater (structure), breakwaters, sea walls, or jetties or they can be constructed by dredging, which requires maintenance by further periodic dredging. An example of an artificial harbor is Long Beach Harbor, California, United States, which was an array of salt marshes and tidal flats too shallow for modern merchant ships before it was first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choke Point
In military strategy, a choke point (or chokepoint), or sometimes bottleneck, is a geographical feature on land such as a valley, defile or bridge, or maritime passage through a critical waterway such as a strait, which an armed force is forced to pass through in order to reach its objective, sometimes on a substantially narrowed front and therefore greatly decreasing its combat effectiveness by making it harder to bring superior numbers to bear. A choke point can allow a numerically inferior defending force to use the terrain as a force multiplier to thwart or ambush a much larger opponent, as the attacker cannot advance any further without first securing passage through the choke point. Historical examples Some historical examples of the tactical use of choke points are King Leonidas I's defense of the Pass of Thermopylae during an invasion led by Xerxes I of Persia; the Battle of Stamford Bridge in which Harold Godwinson defeated Harald Hardrada; William Wallace' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catamaran
A catamaran () (informally, a "cat") is a watercraft with two parallel hull (watercraft), hulls of equal size. The wide distance between a catamaran's hulls imparts stability through resistance to rolling and overturning; no ballast is required. Catamarans typically have less hull volume, smaller Displacement (ship), displacement, and shallower draft (hull), draft (draught) than monohulls of comparable length. The two hulls combined also often have a smaller hydrodynamic drag (physics), resistance than comparable monohulls, requiring less propulsive power from either sails or motors. The catamaran's wider stance on the water can reduce both Heeling (sailing)#Heeling, heeling and wave-induced motion, as compared with a monohull, and can give reduced wakes. Catamarans were invented by the Austronesian peoples, and enabled their expansion to the islands of the Indian Ocean, Indian and Pacific Oceans. Catamarans range in size from small sailing or rowing vessels to large naval s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Dynamics
In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in motion) and (the study of water and other liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moment (physics), moments on aircraft, determining the mass flow rate of petroleum through pipeline transport, pipelines, weather forecasting, predicting weather patterns, understanding nebulae in interstellar space, understanding large scale Geophysical fluid dynamics, geophysical flows involving oceans/atmosphere and Nuclear weapon design, modelling fission weapon detonation. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
