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HMS Ursa (R22)
HMS ''Ursa'' was a U-class destroyer of the Royal Navy that saw service during the Second World War. She was later converted into a Type 15 fast anti-submarine frigate, with the new pennant number F200. Design ''Ursa'' was one of eight U-class destroyers ordered as the 7th Emergency Flotilla on 12 June 1941. The U-class were War Emergency Programme destroyers, intended for general duties, including use as anti-submarine escort, and were to be suitable for mass-production. They were based on the hull and machinery of the pre-war J-class destroyers, but with a lighter armament (effectively whatever armament was available) in order to speed production. The U-class were almost identical to the S-class ordered as the 5th Emergency Flotilla and the R-class ordered as the 6th Emergency Flotilla earlier in the year, but were not fitted for operations in Arctic waters. The U-class were long overall, at the waterline and between perpendiculars, with a beam of and a draugh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John I
John I may refer to: People * John I (bishop of Jerusalem) * John Chrysostom (349 – c. 407), Patriarch of Constantinople * John of Antioch (died 441) * Pope John I, Pope from 523 to 526 * John I (exarch) (died 615), Exarch of Ravenna * John I of Naples (died c. 719) * John of Abkhazia (ruled 878/879–880) * John I of Gaeta (died c. 933) * John I Tzimiskes (c. 925 – 976), Byzantine Emperor * John I of Amalfi (died 1007) * John I of Ponthieu (c. 1147 – 1191) * John I (archbishop of Trier) (c. 1140-1212), Archbishop of Trier from 1190 to 1212 * John of England (1166–1216), King of England, Lord of Ireland, Duke of Normandy and Aquitaine and Count of Anjou * John I of Sweden (c. 1201 – 1222) * John of Brienne (c. 1148 – 1237), king of Jerusalem * John I of Trebizond (died 1238) * John I of Dreux (1215–1249) * John I of Avesnes (1218–1257), Count of Hainaut * John of Brunswick, Duke of Lüneburg (c. 1242–1277) * John I, Count of Blois (died 1280) * John I, Duke of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limbo (weapon)
Limbo, or Anti Submarine Mortar Mark 10 (A/S Mk.10), was the final development of the forward-throwing anti-submarine weapon Squid, designed during the Second World War and was developed by the Admiralty Underwater Weapons Establishment in the 1950s. Limbo was installed on the quarterdeck of Royal Navy escort ships from 1955 to the mid-1980s, Australian–built destroyer and s. Limbo was widely employed by the Royal Canadian Navy, being incorporated into all destroyer designs from the late 1950s to the early 1970s, including the , , , and classes and the Type 12 President Class frigates built for the South African Navy in the 1960s. Operation Limbo was loaded and fired automatically with the crew under-cover and was stabilised in pitch and roll. The firing distance of the mortars was controlled by opening gas vents; rounds could be fired from . The weapon was linked to the sonar system of the ship, firing on command when the target was in range. The rounds were projected so t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Displacement (ship)
The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by the ship, then converting that value into weight. Traditionally, various measurement rules have been in use, giving various measures in long tons. Today, tonnes are more commonly used. Ship displacement varies by a vessel's degree of load, from its empty weight as designed (known as "lightweight tonnage") to its maximum load. Numerous specific terms are used to describe varying levels of load and trim, detailed below. Ship displacement should not be confused with measurements of volume or capacity typically used for commercial vessels and measured by tonnage: net tonnage and gross tonnage. Calculation The process of determining a vessel's displacement begins with measuring its draft.George, 2005. p.5. This is accomplished by means of its "draft marks" (or "load lines"). A mer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Draft (ship)
The draft or draught of a ship's hull is the vertical distance between the waterline and the bottom of the hull (keel). The draught of the vessel is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if deployed. Draft determines the minimum depth of water a ship or boat can safely navigate. The related term air draft is the maximum height of any part of the vessel above the water. The more heavily a vessel is loaded, the deeper it sinks into the water, and the greater its draft. After construction, the shipyard creates a table showing how much water the vessel displaces based on its draft and the density of the water (salt or fresh). The draft can also be used to determine the weight of cargo on board by calculating the total displacement of water, accounting for the content of the ship's bunkers, and using Archimedes' principle. The closely related term "trim" is defined as the difference between the forward and aft ... [...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] |
Length Between Perpendiculars
Length between perpendiculars (often abbreviated as p/p, p.p., pp, LPP, LBP or Length BPP) is the length of a ship along the summer load line from the forward surface of the stem, or main bow perpendicular member, to the after surface of the sternpost, or main stern perpendicular member. When there is no sternpost, the centerline axis of the rudder stock is used as the aft end of the length between perpendiculars. Measuring to the stern post or rudder stock was believed to give a reasonable idea of the ship's carrying capacity, as it excluded the small, often unusable volume contained in her overhanging ends. On some types of vessels this is, for all practical purposes, a waterline measurement. In a ship with raked stems, naturally that length changes as the draught of the ship changes, therefore it is measured from a defined loaded condition. See also * Length overall __NOTOC__ Length overall (LOA, o/a, o.a. or oa) is the maximum length of a vessel's hull measured para ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waterline Length
A vessel's length at the waterline (abbreviated to L.W.L)Note: originally Load Waterline Length is the length of a ship or boat at the level where it sits in the water (the ''waterline''). The LWL will be shorter than the length of the boat overall (''length overall'' or LOA) as most boats have bows and stern protrusions that make the LOA greater than the LWL. As a ship becomes more loaded, it will sit lower in the water and its ambient waterline length may change; but the registered L.W.L it is measured from a default load condition. This measure is significant in determining several of a vessel's properties, such as how much water it displaces, where the bow and stern waves occur, hull speed, amount of bottom-paint needed, etc. Traditionally, a stripe called the "boot top" is painted around the hull just above the waterline. In sailing boats, longer waterline length will usually enable a greater maximum speed, because it allows greater sail area, without increasing beam or d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Length Overall
__NOTOC__ Length overall (LOA, o/a, o.a. or oa) is the maximum length of a vessel's hull measured parallel to the waterline. This length is important while docking the ship. It is the most commonly used way of expressing the size of a ship, and is also used for calculating the cost of a marina berth (for example, £2.50 per metre LOA). LOA is usually measured on the hull alone. For sailing ships, this may ''exclude'' the bowsprit and other fittings added to the hull. This is how some racing boats and tall ships use the term LOA. However, other sources may include bowsprits in LOA. Confusingly, LOA has different meanings. "Sparred length", "Total length including bowsprit", "Mooring length" and "LOA including bowsprit" are other expressions that might indicate the full length of a sailing ship. LOD Often used to distinguish between the length of a vessel including projections (e.g. bow sprits, etc.) from the length of the hull itself, the Length on Deck or LOD is often repor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J-, K- And N-class Destroyer
The J, K and N class consisted of 24 destroyers built for the Royal Navy beginning in 1938. They were a return to a smaller vessel, with a heavier torpedo armament, after the that emphasised guns over torpedoes. The ships were built in three flotillas or groups, each consisting of eight ships with names beginning with "J", "K" and "N". The flag superior of the pennant numbers changed from "F" to "G" in 1940. The ships were modified throughout their wartime service, particularly their anti-aircraft (AA) guns; they were also fitted with radar. Design history The design was intended as a smaller follow-on from the preceding Tribal class, and incorporated one radical new idea that was a departure from all previous Royal Navy destroyer designs. That was the adoption of a two boiler room layout. This reduced hull length and allowed for a single funnel, both reducing the profile and increasing the arcs of fire of the light anti-aircraft (AA) weapons. However, this also increased vu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
War Emergency Programme Destroyers
The War Emergency Programme destroyers were destroyers built for the British Royal Navy during World War I and World War II. World War I emergency programmes The 323 destroyers ordered during the First World War belonged to several different classes and were the subject of 14 separate War Programmes between 1914 and 1918. 40 of these were cancelled at the end of the war. The total excludes destroyers building in UK for other navies which were purchased for the Royal Navy following the outbreak of war. World War II emergency programme The 112 destroyers built during the Second World War were based on the hull and machinery of the earlier J-, K- and N-class destroyers of the 1930s. Each of the fourteen flotillas produced consisted of eight destroyers. Due to supply problems and the persistent failure by the Royal Navy to develop a suitable dual-purpose weapon for destroyers, they were fitted with whatever armament was available. Advances in radar and weaponry were incorporated as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pennant Number
In the Royal Navy and other navies of Europe and the Commonwealth of Nations, ships are identified by pennant number (an internationalisation of ''pendant number'', which it was called before 1948). Historically, naval ships flew a flag that identified a flotilla or type of vessel. For example, the Royal Navy used a red burgee for torpedo boats and a pennant with an H for torpedo boat destroyers. Adding a number to the type-identifying flag uniquely identified each ship. In the current system, a letter prefix, called a ''flag superior'', identifies the type of ship, and numerical suffix, called a flag inferior, uniquely identifies an individual ship. Not all pennant numbers have a flag superior. Royal Navy systems The Royal Navy first used pennants to distinguish its ships in 1661 with a proclamation that all of his majesty's ships must fly a union pennant. This distinction was further strengthened by a proclamation in 1674 which forbade merchant vessels from flying any pennants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frigate
A frigate () is a type of warship. In different eras, the roles and capabilities of ships classified as frigates have varied somewhat. The name frigate in the 17th to early 18th centuries was given to any full-rigged ship built for speed and maneuverability, intended to be used in scouting, escort and patrol roles. The term was applied loosely to ships varying greatly in design. In the second quarter of the 18th century, the 'true frigate' was developed in France. This type of vessel was characterised by possessing only one armed deck, with an unarmed deck below it used for berthing the crew. Late in the 19th century (British and French prototypes were constructed in 1858), armoured frigates were developed as powerful ironclad warships, the term frigate was used because of their single gun deck. Later developments in ironclad ships rendered the frigate designation obsolete and the term fell out of favour. During the Second World War the name 'frigate' was reintroduced to des ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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