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Submarine Development Squadron 12
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 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 navies, large and small. Military uses include attacking enemy surface ships (merchant and military) or other submarines, and for aircraft carrier protection, blockade running, nuclear deterrence, reconnaissance, conventional land attack (for example, using a cruise missile), and covert insertion of spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Navy 040730-N-1234E-002 PCU Virginia (SSN 774) Returns To The General Dynamics Electric Boat Shipyard
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five major unincorporated territories, nine United States Minor Outlying Islands, Minor Outlying Islands, and 326 Indian reservations. The United States is also in Compact of Free Association, free association with three Oceania, Pacific Island Sovereign state, sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Palau, Republic of Palau. It is the world's List of countries and dependencies by area, third-largest country by both land and total area. It shares land borders Canada–United States border, with Canada to its north and Mexico–United States border, with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Special Forces
Special forces and special operations forces (SOF) are military units trained to conduct special operations. NATO has defined special operations as "military activities conducted by specially designated, organized, selected, trained and equipped forces using unconventional techniques and modes of employment". Special forces emerged in the early 20th century, with a significant growth in the field during the Second World War, when "every major army involved in the fighting" created formations devoted to special operations behind enemy lines. Depending on the country, special forces may perform functions including airborne operations, counter-insurgency, counter-terrorism, foreign internal defense, covert ops, direct action, hostage rescue, high-value targets/manhunt, intelligence operations, mobility operations, and unconventional warfare. In Russian-speaking countries, special forces of any country are typically called , an acronym for "special purpose". In the United State ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the displaced fluid. For this reason, an object whose average density is greater than that of the fluid in which it is submerged tends to sink. If the object is less dense than the liquid, the force can keep the object afloat. This can occur only in a no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ballast Tank
A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide hydrostatic stability for a vessel, to reduce or control buoyancy, as in a submarine, to correct trim or list, to provide a more even load distribution along the hull to reduce structural hogging or sagging stresses, or to increase draft, as in a semi-submersible vessel or platform, or a SWATH, to improve seakeeping. Using water in a tank provides easier weight adjustment than the stone or iron ballast used in older vessels, and makes it easy for the crew to reduce a vessel's draft when it enters shallower water, by temporarily pumping out ballast. Airships use ballast tanks mainly to control buoyancy and correct trim. History The basic concept behind the ballast tank can be seen in many forms of aquatic life, such as the blowfish or argonaut octopus. The concept has been invented and reinvented many times by humans to serve a variety of purpo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diving Plane
Diving planes, also known as hydroplanes, are control surfaces found on a submarine which allow the vessel to pitch its bow and stern up or down to assist in the process of submerging or surfacing the boat, as well as controlling depth when submerged. Bow and stern planes Diving planes are usually fitted in two pairs, the '' bow planes'' at the front of the submarine and the ''stern planes'' at the rear. The stern planes function in much the same way as an aircraft's elevator. As the planes are a long distance fore-and-aft from the hull's centre of buoyancy, they introduce a pitching moment. Ballast tanks within the submarine adjust buoyancy to be neutral, making the boat controllable. The position of the planes controls the pitch of the boat and, with the forward motion of the boat, this controls depth. If not carefully controlled, this could lead to a 'porpoising' motion whereby the planesman continually hunts for a stable combination of depth and pitch. For easier berth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boat
A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size, shape, cargo or passenger capacity, or its ability to carry boats. Small boats are typically found on inland waterways such as rivers and lakes, or in protected coastal areas. However, some boats, such as the whaleboat, were intended for use in an offshore environment. In modern naval terms, a boat is a vessel small enough to be carried aboard a ship. Boats vary in proportion and construction methods with their intended purpose, available materials, or local traditions. Canoes have been used since prehistoric times and remain in use throughout the world for transportation, fishing, and sport. Fishing boats vary widely in style partly to match local conditions. Pleasure craft used in recreational boating include ski boats, pontoon boats, and sailboats. House boats may be used for vacationing or long-term residence. Lighters are used to convey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conning Tower
A conning tower is a raised platform on a ship or submarine, often armored, from which an officer in charge can conn the vessel, controlling movements of the ship by giving orders to those responsible for the ship's engine, rudder, lines, and ground tackle. It is usually located as high on the ship as practical, to give the conning team good visibility of the entirety of the ship, ocean conditions, and other vessels. The naval term "conn" may derive from the Middle English ''conne'' (study, become acquainted with) or French ''conduire'' from Latin ''conducere'' (conduct). Surface ships On surface ships, the conning tower was a feature of all battleships and armored cruisers from about 1860 to the early years of World War II. Located at the front end of the superstructure, the conning tower was a heavily armored cylinder, with tiny slit windows on three sides providing a reasonable field of view. Designed to shield just enough personnel and devices for navigation during battle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sail (submarine)
In naval parlance, the sail (American usage) or fin (British/Commonwealth usage) (also known as a fairwater) of a submarine is the tower-like structure found on the dorsal (topside) surface of submarines. Submarine sails once housed the conning tower (command and communications data center), the periscope(s), radar and communications masts (antenna), though most of these functions have now been relocated to the hull proper (and so the sail is no longer considered a "conning tower"). When above the water's surface, the sail serves as an observation platform. It also provides an entrance and exit point on the submarine that has enough freeboard to prevent the submarine being swamped. Under water, the sail acts as a vertical stabilizer. In some submarines, the sail also supports diving planes (or fairwater planes), which are control surfaces used for underwater stability and steering.Office of Naval ResearchSubmarines - How They Work. Retrieved December 24, 2008. See also * Dorsal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periscope
A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position. In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45° angle. This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I. Military personnel also use periscopes in some gun turrets and in armoured vehicles. More complex periscopes using prisms or advanced fiber optics instead of mirrors and providing magnification operate on submarines and in various fields of science. The overall design of the classical submarine periscope is very simple: two telescopes pointed into each other. If the two telescopes have different individual magnification, the difference between them causes an overall magnification or reduction. Early examples Johannes Hevelius described an early ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diving Bell
A diving bell is a rigid chamber used to transport divers from the surface to depth and back in open water, usually for the purpose of performing underwater work. The most common types are the open-bottomed wet bell and the closed bell, which can maintain an internal pressure greater than the external ambient. Diving bells are usually suspended by a cable, and lifted and lowered by a winch from a surface support platform. Unlike a submersible, the diving bell is not designed to move under the control of its occupants, nor to operate independently of its launch and recovery system. The wet bell is a structure with an airtight chamber which is open to the water at the bottom, that is lowered underwater to operate as a base or a means of transport for a small number of divers. Air is trapped inside the bell by pressure of the water at the interface. These were the first type of diving chamber, and are still in use in modified form. The closed bell is a pressure vessel for human ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bathyscaphe
A bathyscaphe ( or ) is a free-diving self-propelled deep-sea submersible, consisting of a crew cabin similar to a bathysphere, but suspended below a float rather than from a surface cable, as in the classic bathysphere design. The float is filled with gasoline because it is readily available, buoyant, and, for all practical purposes, incompressible. The incompressibility of the gasoline means the tanks can be very lightly constructed, since the pressure inside and outside the tanks equalises, eliminating any differential. By contrast, the crew cabin must withstand a huge pressure differential and is massively built. Buoyancy at the surface can be trimmed easily by replacing gasoline with water, which is denser. Auguste Piccard, inventor of the first bathyscaphe, composed the name ''bathyscaphe'' using the Ancient Greek words βαθύς ''bathys'' ("deep") and σκάφος ''skaphos'' ("vessel"/"ship"). Mode of operation To descend, a bathyscaphe floods air tanks with se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undersea Archaeology
Underwater archaeology is archaeology practiced underwater. As with all other branches of archaeology, it evolved from its roots in pre-history and in the classical era to include sites from the historical and industrial eras. Its acceptance has been a relatively late development due to the difficulties of accessing and working underwater sites, and because the application of archaeology to underwater sites initially emerged from the skills and tools developed by shipwreck salvagers. As a result, underwater archaeology initially struggled to establish itself as actual archaeological research. This changed when universities began teaching the subject and a theoretical and practical base for the sub-discipline was firmly established in the late 1980’s. Underwater archaeology now has a number of branches including, maritime archaeology: the scientifically based study of past human life, behaviours and cultures and their activities in, on, around and (lately) under the sea, estuarie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
