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Pump-jet
A pump-jet, hydrojet, or water jet is a marine system that produces a jet of water for propulsion. The mechanical arrangement may be a ducted propeller (axial-flow pump), a centrifugal pump, or a mixed flow pump which is a combination of both centrifugal and axial designs. The design also incorporates an intake to provide water to the pump and a nozzle to direct the flow of water out of the pump. Design A pump-jet works by having an intake (usually at the bottom of the hull) that allows water to pass underneath the vessel into the engines. Water enters the pump through this inlet. The pump can be of a centrifugal design for high speeds, or an axial flow pump for low to medium speeds. The water pressure inside the inlet is increased by the pump and forced backwards through a nozzle. With the use of a ''reversing bucket'', reverse thrust can also be achieved for faring backwards, quickly and without the need to change gear or adjust engine thrust. The reversing bucket ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pump-jet On NatchanWorld 02
A pump-jet, hydrojet, or water jet is a marine system that produces a jet of water for propulsion. The mechanical arrangement may be a ducted propeller (axial-flow pump), a centrifugal pump, or a mixed flow pump which is a combination of both centrifugal and axial designs. The design also incorporates an intake to provide water to the pump and a nozzle to direct the flow of water out of the pump. Design A pump-jet works by having an intake (usually at the bottom of the hull) that allows water to pass underneath the vessel into the engines. Water enters the pump through this inlet. The pump can be of a centrifugal design for high speeds, or an axial flow pump for low to medium speeds. The water pressure inside the inlet is increased by the pump and forced backwards through a nozzle. With the use of a ''reversing bucket'', reverse thrust can also be achieved for faring backwards, quickly and without the need to change gear or adjust engine thrust. The reversing bucket can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Personal Water Craft
A personal watercraft (PWC), also called Jet Ski or water scooter, is a primarily recreational watercraft that is designed to hold only a small number of occupants, who sit or stand on top of the craft, not within the craft as in a boat. Prominent brands of PWCs include Jet Skis and Sea-Doos. PWCs have two style categories. The first and the most popular is a compact runabout, typically holding no more than two or three people, who mainly sit on top of the watercraft as one does when riding an ATV or snowmobile. The second style is a "stand-up" type, typically built for only one occupant who operates the watercraft standing up as in riding a motorized scooter; it is used more for doing tricks, racing, and in competitions. Both styles have an inboard engine driving a pump-jet that has a screw-shaped impeller to create thrust for propulsion and steering. Most are designed for two or three people, though four-passenger models exist. Many of today's models are built for mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine Propulsion
Marine propulsion is the mechanism or system used to generate thrust to move a watercraft through water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting of an electric motor or internal combustion engine driving a propeller, or less frequently, in pump-jets, an impeller. Marine engineering is the discipline concerned with the engineering design process of marine propulsion systems. Human-powered watercraft, Human-powered paddles and oars, and later, sails were the first forms of marine propulsion. Rowed galleys, some equipped with sail, played an important early role in early human seafaring and naval warfare, warfare. The first advanced mechanical means of marine propulsion was the marine steam engine, introduced in the early 19th century. During the 20th century it was replaced by two-stroke diesel engine, two-stroke or four-stroke diesel engines, outboard motors, and gas turbine engines on faster sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
French Barracuda-class Submarine
The ''Suffren''-class is a class of nuclear-powered attack submarines, designed by the French shipbuilder Naval Group (formerly DCNS) for the French Navy. It is intended to replace the s. Construction began in 2007 and the lead boat of the class, , was commissioned on 6 November 2020. It officially entered active service on 3 June 2022. History Development In October 1998, the '' Delegation Générale pour l'Armement'', the French government's defense procurement agency, established an integrated project team consisting of the Naval Staff, DCN (now known as Naval Group), Technicatome and the '' Commissariat à l'Énergie Atomique'', a regulatory body that oversees nuclear power plants, to oversee a program the design of a new attack submarine class, called Barracuda. DCN was to be the boat's designer and builder while Technicatome (since acquired by Areva) was to be responsible for the nuclear power plant. The two companies were to act jointly as a single prime contracto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stealth Ship
A stealth ship is a ship that employs stealth technology construction techniques in an effort to make it harder to detect by one or more of radar, visual, sonar, and infrared methods. These techniques borrow from stealth aircraft technology, although some aspects such as wake and acoustic signature reduction ( acoustic quieting) are unique to stealth ships' design. Although radar cross-section (RCS) reduction is a fairly new concept, many other forms of masking a ship have existed for centuries or even millennia. Shaping In designing a ship with a reduced radar signature, the main concerns are radar beams originating near or slightly above the horizon (as seen from the ship) coming from distant patrol aircraft, other ships, or sea-skimming anti-ship missiles with active radar seekers. Therefore, the shape of the ship avoids vertical surfaces, which are effective at reflecting such beams directly back to the emitter. Retro-reflective right angles are eliminated to avoid the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine
A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or informally to refer to remotely operated vehicles and Autonomous underwater vehicle, robots, or to medium-sized or smaller vessels (such as the midget submarine and the wet sub). Submarines are referred to as ''boats'' rather than ''ships'' regardless of their size. Although experimental submarines had been built earlier, submarine design took off during the 19th century, and submarines were adopted by several navies. They were first used widely during World War I (1914–1918), and are now used in many navy, navies, large and small. Their military uses include: attacking enemy surface ships (merchant and military) or other submarines; aircraft carrier protection; Blockade runner, blockade running; Ballistic missile submarine, nuclear deterrenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ducted Propeller
A ducted propeller, also known as a Kort nozzle, is a marine propeller shrouded with a non-rotating nozzle. It is used to improve the efficiency of the propeller and is especially used on heavily loaded propellers or propellers with limited diameter. It was developed first by Luigi Stipa (1931) and later by Ludwig Kort (1934). The cross-section of the shroud has the form of a foil, and the shroud can offer hydrodynamic advantages over bare propellers, under certain conditions. Advantages are increased efficiency at lower speeds (10 knots), course stability when sailing astern, and increase of cavitation. Ducted propellers are also used to replace rudders. History Luigi Stipa in 1931 and later Ludwig Kort (1934) demonstrated that an increase in propulsive efficiency could be achieved by surrounding the propeller with a foil-shaped shroud in the case of heavily loaded propellers. A "Kort Nozzle" is referred to as an accelerating nozzle and is generally a MARIN 19A profile o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 million tons in 2021. It has the world's largest aircraft carrier fleet, with List of aircraft carriers in service, eleven in service, one undergoing trials, two new carriers under construction, and six other carriers planned as of 2024. With 336,978 personnel on active duty and 101,583 in the Ready Reserve, the U.S. Navy is the third largest of the United States military service branches in terms of personnel. It has 299 deployable combat vessels and about 4,012 operational aircraft as of 18 July 2023. The U.S. Navy is one of six United States Armed Forces, armed forces of the United States and one of eight uniformed services of the United States. The United States Navy traces its origins to the Continental Navy, which was established during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Navy
The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom of England, English and Kingdom of Scotland, Scottish kings from the early Middle Ages, medieval period, the first major maritime engagements were fought in the Hundred Years' War against Kingdom of France, France. The modern Royal Navy traces its origins to the English Navy of the early 16th century; the oldest of the British Armed Forces, UK's armed services, it is consequently known as the Senior Service. From the early 18th century until the World War II, Second World War, it was the world's most powerful navy. The Royal Navy played a key part in establishing and defending the British Empire, and four Imperial fortress colonies and a string of imperial bases and coaling stations secured the Royal Navy's ability to assert naval superior ... [...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] |
Swedish Navy
The Swedish Navy () is the maritime service branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet (), formally sometimes referred to as the Royal Navy () – as well as marine units, the Amphibious Corps (). Founded under King Gustav Vasa in 1522, the Swedish navy is one of the oldest continuously serving navies in the world, celebrating its 500th anniversary in 2022. History Early Swedish kings ( 9th–14th centuries) organised a Swedish Navy along the coastline through . This involved combined rowing and sailing ships (without artillery). This system became obsolete with the development of society and changes in military technology. No later than in the 14th century, the duty to serve in was replaced by a tax. In 1427, when Sweden was part of the Kalmar Union (with Denmark and Norway), Swedish warships did however participate in the naval battle of Öresund against the Hanseatic League. It is unclear how this force was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Warships
A warship or combatant ship is a naval ship that is used for naval warfare. Usually they belong to the navy branch of the armed forces of a nation, though they have also been operated by individuals, cooperatives and corporations. As well as being armed, warships are designed to withstand damage and are typically faster and more maneuverable than merchant ships. Unlike a merchant ship, which carries cargo, a warship typically carries only weapons, ammunition and supplies for its crew. In wartime, the distinction between warships and merchant ships is often blurred. Until the 17th century it was common for merchant ships to be pressed into naval service, and not unusual for more than half of a fleet to be composed of merchant ships—there was not a large difference in construction, unlike the difference between a heavily armoured battleship and an ocean liner. Until the threat of piracy subsided in the 19th century, it was normal practice to arm larger merchant ships such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
