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Hildur-class Monitor
The ''Hildur-class'' monitors consisted of seven monitors built for the Swedish Navy in the 1870s. They were sold in 1919 and most were converted into fuel oil barges. One such ship, , has been converted into a museum ship. Design and description The ''Hildur''-class monitors were designed by Lieutenant John Christian d'Ailly, from a proposal by John Ericsson, for the defense of Lake Mälaren and the Stockholm archipelago. The ships were long overall and had a beam of . They had a draft of and displaced . The crew of the first two monitors, ''Hildur'' and ''Gerda'', numbered 42 officers and men, the others had 48-man crews. ''Hildur'' and ''Gerda'' only had a stern rudder, the other had rudders at bow and stern. Bow rudders were fitted to the older ships when they were reconstructed.Harris, pp. 30–32 The ''Hildur''s had a pair of two-cylinder horizontal-return connecting-rod steam engines, each driving a single propeller using steam from two cylindrical boilers. The engines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Ship
The lead ship, name ship, or class leader is the first of a series or class of ships all constructed according to the same general design. The term is applicable to naval ships and large civilian vessels. Large ships are very complex and may take as many as five to ten years to build. Improvements based on experience with building and operating the lead ship are likely to be incorporated into the design or construction of later ships in the class, so it is rare to have vessels that are identical. The second and later ships are often started before the first one is completed, launched and tested. Nevertheless, building copies is still more efficient and cost-effective than building prototypes, and the lead ship will usually be followed by copies with some improvements rather than radically different versions. The improvements will sometimes be retrofitted to the lead ship. Occasionally, the lead ship will be launched and commissioned for shakedown testing before following ship ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beam (nautical)
The beam of a ship is its width at its widest point. The maximum beam (BMAX) is the distance between planes passing through the outer extremities of the ship, beam of the hull (BH) only includes permanently fixed parts of the hull, and beam at waterline (BWL) is the maximum width where the hull intersects the surface of the water. Generally speaking, the wider the beam of a ship (or boat), the more initial stability it has, at the expense of secondary stability in the event of a capsize, where more energy is required to right the vessel from its inverted position. A ship that heels on her ''beam ends'' has her deck beams nearly vertical. Typical values Typical length-to-beam ratios ( aspect ratios) for small sailboats are from 2:1 (dinghies to trailerable sailboats around ) to 5:1 (racing sailboats over ). Large ships have widely varying beam ratios, some as large as 20:1. Rowing shells designed for flatwater racing may have length to beam ratios as high as 30:1, while a cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motala Verkstad
AB Motala Verkstad is one of the oldest engineering companies in Sweden. The company was founded in 1822 during the construction of Göta Canal. Motala Verkstad has also built about 400 ships, 800 bridges (e.g. Västerbron, Skeppsholmsbron, Bergsnäsbron and the Ahvaz Bridge in Iran), railway equipment, 1300 locomotives. The 118-meter-tall towers of Uppsala Cathedral were also built by Motala Verkstad. During the 1970s the company was the world's largest exporter of kitchen sinks and during the 1980s they built landing gear for Swedish-built aircraft. Today the company employs about 180 people. History Motala Verkstad was started in 1822 on Baltzar von Platen's initiative. Von Platen realized the importance of having local technical knowledge during the construction of the channel. The first leader was Daniel Fraser. Ships built at Motala Verkstad * ''Hildur''-class monitors (1870s) * M/S ''Juno'' (1874) * SS ''Nya Svartsjölandet'' (1900, now MV ''Västan'') * SS ''A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceremonial Ship 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] |
Laid Down
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] |
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] |
Wrought Iron
Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag Inclusion (mineral), inclusions (up to 2% by weight), which give it a wood-like "grain" that is visible when it is etched, rusted, or bent to structural failure, failure. Wrought iron is tough, malleable, ductile, corrosion resistant, and easily forge welding, forge welded, but is more difficult to welding, weld electrically. Before the development of effective methods of steelmaking and the availability of large quantities of steel, wrought iron was the most common form of malleable iron. It was given the name ''wrought'' because it was hammered, rolled, or otherwise worked while hot enough to expel molten slag. The modern functional equivalent of wrought iron is Carbon steel#Mild or low-carbon steel, mild steel, also called low-carbon steel. Neither wrought iron nor mild steel contain enough carbon to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waterline
The waterline is the line where the hull of a ship meets the surface of the water. Specifically, it is also the name of a special marking, also known as an international load line, Plimsoll line and water line (positioned amidships), that indicates the draft of the ship and the legal limit to which a ship may be loaded for specific water types and temperatures in order to safely maintain buoyancy, particularly with regard to the hazard of waves that may arise. Varying water temperatures will affect a ship's draft, because warm water is less dense than cold water, providing less buoyancy. In the same way, fresh water is less dense than salinated or seawater with a similar lessening effect upon buoyancy. For vessels with displacement hulls, the hull speed is defined by, among other things, the waterline length. In a sailing boat, the waterline length can change significantly as the boat heels, and can dynamically affect the speed of the boat. A waterline can also refer to any l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quick-firing Gun
A quick-firing or rapid-firing gun is an artillery piece, typically a gun or howitzer, which has several characteristics which taken together mean the weapon can fire at a fast rate. Quick-firing was introduced worldwide in the 1880s and 1890s and had a marked impact on war both on land and at sea. Characteristics The characteristics of a quick-firing artillery piece are: *A breech-loading weapon with a breech mechanism that allows rapid reloading *Single-part cased ammunition, i.e. a cartridge containing both shell and propellant *Recoil buffers to limit recoil, so the barrel can quickly return to the same position after firing *The use of smokeless powder – nitrocellulose, nitroglycerine, or cordite – which create far less smoke than gunpowder, meaning that gun crews could still see their target These innovations, taken together, meant that the quick-firer could fire aimed shells much more rapidly than an older weapon. For instance, an Elswick Ordnance Company 4.7-inch gun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muzzle Velocity
Muzzle velocity is the speed of a projectile (bullet, pellet, slug, ball/shots or shell) with respect to the muzzle at the moment it leaves the end of a gun's barrel (i.e. the muzzle). Firearm muzzle velocities range from approximately to in black powder muskets, to more than in modern rifles with high-velocity cartridges such as the .220 Swift and .204 Ruger, all the way to for tank guns firing kinetic energy penetrator ammunition. To simulate orbital debris impacts on spacecraft, NASA launches projectiles through light-gas guns at speeds up to . Projectile velocity For projectiles in unpowered flight, its velocity is highest at leaving the muzzle and drops off steadily because of air resistance. Projectiles traveling less than the speed of sound (about in dry air at sea level) are ''subsonic'', while those traveling faster are ''supersonic'' and thus can travel a substantial distance and even hit a target before a nearby observer hears the "bang" of the shot. Projec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gun Turret
A gun turret (or simply turret) is a mounting platform from which weapons can be fired that affords protection, visibility and ability to turn and aim. A modern gun turret is generally a rotatable weapon mount that houses the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in some degree of azimuth and elevation (cone of fire). Description Rotating gun turrets protect the weapon and its crew as they rotate. When this meaning of the word "turret" started being used at the beginning of the 1860s, turrets were normally cylindrical. Barbettes were an alternative to turrets; with a barbette the protection was fixed, and the weapon and crew were on a rotating platform inside the barbette. In the 1890s, armoured hoods (also known as "gun houses") were added to barbettes; these rotated with the platform (hence the term "hooded barbette"). By the early 20th Century, these hoods were known as turrets. Modern warships have gu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rifled Breech Loader
A rifled breech loader (RBL) is an artillery piece which, unlike the smoothbore cannon and rifled muzzle loader (RML) which preceded it, has rifling in the barrel and is loaded from the breech at the rear of the gun. The spin imparted by the gun's rifling gives projectiles directional stability and increased range. Loading from the rear of the gun leaves the crew less exposed to enemy fire, allows smaller gun emplacements or turrets, and allows a faster rate of fire. Overview The major problem to be solved with breechloading artillery was obturation: the sealing of the breech after firing to ensure that none of the gases generated by the burning of the propellant (initially gunpowder) escaped rearwards through the breech. This was both a safety issue and one of gun performance – all the propellant gas was needed to accelerate the projectile along the barrel. The second problem was speed of operation – how to close the breech before firing and open it after firing as quickly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
