Bofors 40 mm gun
The Bofors 40 mm gun referred to as the Bofors gun, is an anti-aircraft autocannon designed in the 1930s by the Swedish arms manufacturer AB Bofors. It was one of the most popular medium-weight anti-aircraft systems during World War II, used by most of the western Allies as well some captured systems being used by the Axis powers. A small number of these weapons remain in service to this day, saw action as late as the Persian Gulf War. In the post-war era, the original design was not suitable for action against jet-powered aircraft, so Bofors introduced a new model of more power, the 40 mm L/70. In spite of sharing nothing with the original design other than the calibre and the distinctive conical flash hider, this weapon is widely known as "the Bofors". Although not as popular as the original L/60 model, the L/70 remains in service as a multi-purpose weapon for light armoured vehicles, as on the CV 90. Bofors has been part of BAE Systems AB since March 2005; the Swedish Navy purchased a number of 2-pounder Pom-Poms from Vickers as anti-aircraft guns in 1922.
The Navy approached Bofors about the development of a more capable replacement. Bofors signed a contract in late 1928. Bofors produced a gun, a smaller version of a 57 mm semi-automatic gun developed as an anti-torpedo boat weapon in the late 19th century by Finspång, their first test gun was a re-barreled Nordenfelt version of the Finspong gun, to, added a semi-automatic loading mechanism. Testing of this gun in 1929 demonstrated that a problem existed feeding the weapon in order to maintain a reasonable rate of fire. A mechanism, strong enough to handle the stresses of moving the large round was too heavy to move enough to fire rapidly. One attempt to solve this problem used zinc shell cases; this proved to leave heavy zinc deposits in the barrel, had to be abandoned. In the summer of 1930 experiments were made with a new test gun that did away with controlled feed and instead flicked the spent casing out the rear whereafter a second mechanism reloaded the gun by "throwing" a fresh round from the magazine into the open breech.
This seemed to be the solution they needed, improving firing rates to an acceptable level, the work on a prototype commenced soon after. During this period Krupp purchased a one-third share of Bofors. Krupp engineers started the process of updating the Bofors factories to use modern equipment and metallurgy, but the 40 mm project was kept secret; the prototype was completed and fired in November 1931, by the middle of the month it was firing strings of two and three rounds. Changes to the feed mechanism were all that remained, by the end of the year it was operating at 130 rounds per minute. Continued development was needed to turn it into a weapon suitable for production, completed in October 1933. Since acceptance trials had been passed the year before, this became known as the "40 mm akan M/32". Most forces referred to it as the "Bofors 40 mm L/60", although the barrel was 56.25 calibres in length, not the 60 calibres that the name implies. The gun fired a 900 g high explosive 40 × 311R shell at 2,960 ft/s.
The rate of fire was about 120 rounds per minute, which improved when the barrels were closer to the horizontal as gravity assisted the feeding from the top-mounted magazine. In practice firing rates were closer to 80–100 rpm, as the rounds were fed into the breech from four round clips which had to be replaced by hand; the maximum attainable ceiling was 7,200 m. The gun was provided with an advanced sighting system; the trainer and layer were both provided with reflector sights for aiming, while a third crew-member standing behind them "adjusted" for lead using a simple mechanical computer. Power for the sights was supplied from a 6V battery. In spite of the successful development, the Swedish Navy changed its mind and decided it needed a smaller hand-traversed weapon of 13 mm-25 mm size, tested various designs from foreign suppliers. With the 40 mm well along in development, Bofors offered a 25 mm version in 1932, selected as the Bofors 25 mm M/32; the first version of the 40 mm the Navy ordered was intended for use on submarines, where the larger calibre allowed the gun to be used for both AA and against smaller ships.
The barrel was shorter at 42 calibers long, with the effect of reducing the muzzle velocity to about 700 m/s. When not in use, the gun retracted into a watertight cylinder; the only known submarines that used this arrangement was the Sjölejonet-class boats. The guns were removed as the subs were modified with streamlined conning towers; the first order for the "real" L/60 was made by the Dutch Navy, who ordered five twin-gun mounts for the cruiser De Ruyter in August 1934. These guns were stabilized using the Hazemeyer mount, in which one set of layers aimed the gun, while a second manually stabilized the platform the gun sat on. All five mounts were operated by one fire control system. Bofors developed a towable carriage which they displayed in April 1935 at a show in Belgium; this mount allowed the gun to be fired from the carriage with no setup required, although with limited accuracy. If time was available for setup, the gunners used the tow-bar and muzzle lock as levers, raising the wheels off the ground and thereby lowering the gun onto supporting pads.
Two additional legs folded out to the sides, the platform was leveled with hand cranks. The entire setup process could be completed in under a minute. Orders for the land based versions were immediate, starting with
Ceremonial ship launching
Ceremonial ship launching is the process of transferring a vessel to the water. It is a naval tradition in many cultures, it has been observed as a solemn blessing. Ship launching imposes stresses on the ship not met during normal operation, in addition to the size and weight of the vessel, it represents a considerable engineering challenge as well as a public spectacle; the process 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. 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, most used is the end-on launch, in which the vessel slides down an inclined slipway stern first. With the side launch, the ship enters the water broadside; this method came into use in the 19th-century on inland waters and lakes, was more adopted during World War II. The third method is float-out, used for ships that are built in basins or dry docks and floated by admitting water into the dock.
If launched in a restrictive waterway drag chains are used to slow the ship speed to prevent it striking the opposite bank. Ways are arranged perpendicular to the shore line and the ship is built with its stern facing the water. Where the launch takes place into a narrow river, the building slips may be at a shallow angle rather than perpendicular though this requires a longer slipway when launching. Modern slipways take the form of a reinforced concrete mat of sufficient strength to support the vessel, with two "barricades" that extend well below the water level taking into account tidal variations; the barricades support the two launch ways. The vessel is built upon temporary cribbing, arranged to give access to the hull's outer bottom and to allow the launchways to be erected under the complete hull; when it is time to prepare for launching, a pair of standing ways is erected under the hull and out onto the barricades. The surface of the ways is greased. A pair of sliding ways is placed on top, under the hull, a launch cradle with bow and stern poppets is erected on these sliding ways.
The weight of the hull is transferred from the build cribbing onto the launch cradle. Provision is made to hold the vessel in place and release it at the appropriate moment in the launching ceremony. On launching, the vessel slides backwards down the slipway on the ways; some slipways is launched sideways. This is done where the limitations of the water channel would not allow lengthwise launching, but occupies a much greater length of shore; the Great Eastern designed by Brunel was built this way as were many landing craft during World War II. This method requires many more sets of ways to support the weight of the ship. Sometimes ships are launched using a series of inflated tubes underneath the hull, which deflate to cause a downward slope into the water; this procedure has the advantages of requiring less permanent infrastructure and cost. The airbags provide support to the hull of the ship and aid its launching motion into the water, thus this method is arguably safer than other options such as sideways launching.
These airbags are cylindrical in shape with hemispherical heads at both ends. The Xiao Qinghe shipyard launched a tank barge with marine airbags on January 20, 1981, the first known use of marine airbags. A Babylonian narrative dating from the 3rd millennium BC describes the completion of a ship: Openings to the water I stopped. Egyptians and Romans called on their gods to protect seamen. Favor was evoked from the monarch of the seas—Poseidon in Greek mythology, Neptune in Roman mythology. Ship launching participants in ancient Greece wreathed their heads with olive branches, drank wine to honor the gods, poured water on the new vessel as a symbol of blessing. Shrines were carried on board Greek and Roman ships, this practice extended into the Middle Ages; the shrine was placed at the quarterdeck, an area which continues to have special ceremonial significance. Different peoples and cultures shaped the religious ceremonies surrounding a ship launching. Jews and Christians customarily used wine and water as they called upon God to safeguard them at sea.
Intercession of the saints and the blessing of the church were asked by Christians. Ship launchings in the Ottoman Empire were accompanied by prayers to Allah, the sacrifice of sheep, appropriate feasting. Chaplain Henry Teonge of Britain's Royal Navy left an interesting account of a warship launch, a "briganteen of 23 oars," by the Knights of Malta in 1675: Two friars and an attendant went into the vessel, kneeling down prayed halfe an houre, layd their hands on every mast, other places of the vessel, sprinkled her all over with holy water, they came out and hoysted a pendent to signify she was a man of war. The liturgical aspects of ship christenings, or baptisms, continued in Catholic countries, while the Reformation seems to have put a stop to them for a time in Protestant Europe. By the 17th century, for example, English launchings were secular affairs; the christening party for the launch of the
A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until 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. Mines can be laid in many ways: by purpose-built minelayers, refitted ships, submarines, or aircraft—and by dropping them into a harbour by hand, they can be inexpensive: some variants can cost as little as US$2000, though more sophisticated mines can cost millions of dollars, be equipped with several kinds of sensors, deliver a warhead by rocket or torpedo. Their flexibility and cost-effectiveness make mines attractive to the less powerful belligerent in asymmetric warfare; the cost of producing and laying a mine is between 0.5% and 10% of the cost of removing it, it can take up to 200 times as long to clear a minefield as to lay it. Parts of some World War II naval minefields still exist because they are too extensive and expensive to clear.
It is possible for some of these 1940s-era mines to remain dangerous for many years to come. Mines have been employed as offensive or defensive weapons in rivers, estuaries and oceans, but they can be used as tools of psychological warfare. Offensive mines are placed in enemy waters, outside harbours and across important shipping routes with the aim of sinking both merchant and military vessels. Defensive minefields safeguard key stretches of coast from enemy ships and submarines, forcing them into more defended areas, or keeping them away from sensitive ones. Minefields designed for psychological effect are placed on trade routes and are used to stop shipping from reaching an enemy nation, they are spread thinly, to create an impression of minefields existing across large areas. A single mine inserted strategically on a shipping route can stop maritime movements for days while the entire area is swept. International law requires nations to declare when they mine an area, to make it easier for civil shipping to avoid the mines.
The warnings do not have to be specific. Precursors to naval mines were first invented by Chinese innovators of Imperial China and were described in thorough detail by the early Ming dynasty artillery officer Jiao Yu, in his 14th century military treatise known as the Huolongjing. Chinese records tell of naval explosives in the 16th century, used to fight against Japanese pirates; this kind of naval mine was loaded in a wooden box, sealed with putty. General Qi Jiguang made several timed, to harass Japanese pirate ships; the Tiangong Kaiwu treatise, written by Song Yingxing in 1637 AD, describes naval mines with a rip cord pulled by hidden ambushers located on the nearby shore who rotated a steel wheellock flint mechanism to produce sparks and ignite the fuse of the naval mine. Although this is the rotating steel wheellock's first use in naval mines, Jiao Yu had described their use for land mines back in the 14th century; the first plan for a sea mine in the West was by Ralph Rabbards, who presented his design to Queen Elizabeth I of England in 1574.
The Dutch inventor Cornelius Drebbel was employed in the Office of Ordnance by King Charles I of England to make weapons, including a "floating petard" which proved a failure. Weapons of this type were tried by the English at the Siege of La Rochelle in 1627. American David Bushnell developed the first American naval mine for use against the British in the American War of Independence, it was a watertight keg filled with gunpowder, floated toward the enemy, detonated by a sparking mechanism if it struck a ship. It was used on the Delaware River as a drift mine. In 1812 Russian engineer Pavel Shilling exploded an underwater mine using an electrical circuit. In 1842 Samuel Colt used an electric detonator to destroy a moving vessel to demonstrate an underwater mine of his own design to the United States Navy and President John Tyler. However, opposition from former President John Quincy Adams scuttled the project as "not fair and honest warfare." In 1854, during the unsuccessful attempt of the Anglo-French fleet to seize the Kronstadt fortress, British steamships HMS Merlin, HMS Vulture and HMS Firefly suffered damage due to the underwater explosions of Russian naval mines.
Russian naval specialists set more than 1500 naval mines, or infernal machines, designed by Moritz von Jacobi and by Immanuel Nobel, in the Gulf of Finland during the Crimean War of 1853-1856. The mining of Vulcan led to the world's first minesweeping operation. During the next 72 hours, 33 mines were swept; the Jacobi mine was designed by German-born, Russian engineer Jacobi, in 1853. The mine was tied to the sea bottom by an anchor. A cable connected it to a galvanic cell which powered it from the shore, the power of its explosive charge was equal to 14 kilograms of black powder. In the summer of 1853, the production of the mine was approved by the Committee for Mines of the Ministry of War of the Russian Empire. In 1854, 60 Jacobi mines were laid in the vicinity of the Forts Pavel and Alexander, to deter the British Baltic Fleet from attacking them, it phased out its direct competitor the Nobel mine on the insistence of Admiral Fyodor Litke. The Nobel mines were bought from Swedish industrialist Immanuel Nobel who had entered into collusion with Russian head of navy Alexander Sergeyevich Menshikov.
Despite their high cost t
United States Seventh Fleet
The Seventh Fleet is a numbered fleet of the United States Navy. It is headquartered at U. S. Fleet Activities Yokosuka, in Yokosuka, Kanagawa Prefecture, Japan, it is part of the United States Pacific Fleet. At present, it is the largest of the forward-deployed U. S. fleets, with 60 to 70 ships, 300 aircraft and 40,000 Navy and Marine Corps personnel. Its principal responsibilities are to provide joint command in natural disaster or military operations and operational command of all naval forces in the region; the Seventh Fleet was formed on 15 March 1943 in Brisbane, during the World War II, under the command of Admiral Arthur S. "Chips" Carpender. It served in the South West Pacific Area under General Douglas MacArthur; the Seventh Fleet commander served as commander of Allied naval forces in the SWPA. Most of the ships of the Royal Australian Navy were part of the fleet from 1943 to 1945 as part of Task Force 74; the Seventh Fleet—under Admiral Thomas C. Kinkaid—formed a large part of the Allied forces at the Battle of Leyte Gulf, the largest naval battle in history, in October 1944.
The Seventh Fleet fought in two of the Battle Leyte Gulf′s main actions, the Battle of Surigao Strait and the Battle off Samar. After the end of the war, the 7th Fleet moved its headquarters to China; as laid out in Operation Plan 13–45 of 26 August 1945, Kinkaid established five major task forces to manage operations in the Western Pacific: Task Force 71, the North China Force with 75 ships. After the war, on 1 January 1947, the Fleet's name was changed to Naval Forces Western Pacific. In late 1948, the Fleet moved its principal base of operations to the Philippines, where the Navy, following the war, had developed new facilities at Subic Bay and an airfield at Sangley Point. Peacetime operations of the Seventh Fleet were under the control of Commander in Chief Pacific Fleet, Admiral Arthur W. Radford, but standing orders provided that, when operating in Japanese waters or in the event of an emergency, control would pass to Commander, Naval Forces Far East, a component of General Douglas MacArthur's occupation force.
On 19 August 1949 the force was designated as United States Seventh Task Fleet. On 11 February 1950, just prior to the outbreak of the Korean War, the force assumed the name United States Seventh Fleet, which it holds today. Seventh Fleet units participated in all major operations of the Vietnamese Wars; the first Navy jet aircraft used in combat was launched from a Task Force 77 aircraft carrier on 3 July 1950. The landings at Inchon, Korea were conducted by Seventh Fleet amphibious ships; the battleships Iowa, New Jersey and Wisconsin all served as flagships for Commander, U. S. Seventh Fleet during the Korean War. During the Korean War, the Seventh Fleet consisted of Task Force 70, a maritime patrol force provided by Fleet Air Wing One and Fleet Air Wing Six, Task Force 72, the Formosa Patrol, Task Force 77, Task Force 79, a service support squadron. Over the next decade the Seventh Fleet responded to numerous crisis situations including contingency operations conducted in Laos in 1959 and Thailand in 1962.
During September 1959, in the autumn of 1960, again in January 1961, the Seventh Fleet deployed multiship carrier task forces into the South China Sea. Although the Pathet Lao and North Vietnamese supporting forces withdrew in each crisis, in the spring of 1961 their offensive appeared on the verge of overwhelming the pro-American Royal Lao Army. Once again the fleet moved into Southeast Asian waters. By the end of April 1961, most of the Seventh Fleet was deployed off the Indochinese Peninsula preparing to initiate operations into Laos; the force consisted of the Coral Sea and Midway carrier battle groups, antisubmarine support carrier Kearsarge, one helicopter carrier, three groups of amphibious ships, two submarines, three Marine battalion landing teams. At the same time, shorebased air patrol squadrons and another three Marine battalion landing teams stood ready in Okinawa and the Philippines to support the afloat force. Although the administration of President John F. Kennedy had decided against American intervention to rescue the Laotian government, Communist forces halted their advance and agreed to negotiations.
The contending Laotian factions concluded a cease-fire on 8 May 1961. In June 1963 the Seventh Fleet held'Flagpole'63,' a joint naval exercise with the Republic of Korea. Seventh Fleet represented the first official entrance of the United States into the Vietnam War, with the Gulf of Tonkin incident. Between 1950 and 1970, the U. S. Seventh Fleet was known by the tongue-in-cheek nickname "Tonkin Gulf Yacht Club" since most of the fleet's operations were conducted from the Tonkin Gulf at the time. On 12 February 1965, USS Salisbury Sound became the first U. S. Navy ship to conduct operations inside Vietnam coastal waters. Salisbury Sound set up a seadrome in Da Nang Bay and conducted seaplane patrols in support of Operation Flaming Dart, the bombing of North Vietnamese army camps. Operating from Yankee Station off the north coast of Vietnam and the aptly-named Dixie Station off the south coast of Vietnam in the South China Sea,Seventh Fleet was organized into a series of task forces, often
A convoy is a group of vehicles motor vehicles or ships, traveling together for mutual support and protection. A convoy is organized with armed defensive support, it may be used in a non-military sense, for example when driving through remote areas. Arriving at the scene of a major emergency with a well-ordered unit and intact command structure can be another motivation. Naval convoys have been in use for centuries, with examples of merchant ships traveling under naval protection dating to the 12th century; the use of organized naval convoys dates from when ships began to be separated into specialist classes and national navies were established. By the French Revolutionary Wars of the late 18th century, effective naval convoy tactics had been developed to ward off pirates and privateers; some convoys contained several hundred merchant ships. The most enduring system of convoys were the Spanish treasure fleets, that sailed from the 1520s until 1790; when merchant ships sailed independently, a privateer could cruise a shipping lane and capture ships as they passed.
Ships sailing in convoy presented a much smaller target: a convoy was as hard to find as a single ship. If the privateer found a convoy and the wind was favourable for an attack, it could still hope to capture only a handful of ships before the rest managed to escape, a small escort of warships could thwart it; as a result of the convoy system's effectiveness, wartime insurance premiums were lower for ships that sailed in convoys. Many naval battles in the Age of Sail were fought around convoys, including: The Battle of Portland The Battle of Ushant The Battle of Dogger Bank The Glorious First of June The Battle of Pulo Aura By the end of the Napoleonic Wars the Royal Navy had in place a sophisticated convoy system to protect merchant ships. Losses of ships travelling out of convoy however were so high that no merchant ship was allowed to sail unescorted. In the early 20th century, the dreadnought changed the balance of power in convoy battles. Steaming faster than merchant ships and firing at long ranges, a single battleship could destroy many ships in a convoy before the others could scatter over the horizon.
To protect a convoy against a capital ship required providing it with an escort of another capital ship, at high opportunity cost. Battleships were the main reason that the British Admiralty did not adopt convoy tactics at the start of the first Battle of the Atlantic in World War I, but the German capital ships had been bottled up in the North Sea, the main threat to shipping came from U-boats. From a tactical point of view, World War I–era submarines were similar to privateers in the age of sail; these submarines were only a little faster than the merchant ships they were attacking, capable of sinking only a small number of vessels in a convoy because of their limited supply of torpedoes and shells. The Admiralty took a long time to respond to this change in the tactical position, in April 1917 convoys were trialled, before being introduced in the Atlantic in September 1917. Other arguments against convoys were raised; the primary issue was the loss of productivity, as merchant shipping in convoy has to travel at the speed of the slowest vessel in the convoy and spent a considerable amount of time in ports waiting for the next convoy to depart.
Further, large convoys were thought to overload port resources. Actual analysis of shipping losses in World War I disproved all these arguments, at least so far as they applied to transatlantic and other long-distance traffic. Ships sailing in convoys were far less to be sunk when not provided with an escort; the loss of productivity due to convoy delays was small compared with the loss of productivity due to ships being sunk. Ports could deal more with convoys because they tended to arrive on schedule and so loading and unloading could be planned. In his book On the Psychology of Military Incompetence, Norman Dixon suggested that the hostility towards convoys in the naval establishment were in part caused by a perception of convoys as effeminating, due to warships having to care for civilian merchant ships. Convoy duty exposes the escorting warships to the sometimes hazardous conditions of the North Atlantic, with only rare occurrences of visible achievement; the British adopted a convoy system voluntary and compulsory for all merchant ships, the moment that World War II was declared.
Each convoy consisted of between 30 and 70 unarmed merchant ships. Canadian, American, supplies were vital for Britain to continue its war effort; the course of the Battle of the Atlantic was a long struggle as the Germans developed anti-convoy tactics and the British developed counter-tactics to thwart the Germans. The capability of a armed warship against a convoy was illustrated by the fate of Convoy HX 84. On November 5, 1940, the German heavy cruiser Admiral Scheer encountered the convoy. Maiden, Kenbame Head and Fresno were sunk, other ships were damaged. Only the sacrifice of the Armed Merchant Cruiser HMS Jervis Bay and failing light allowed the rest of the convoy to escape; the deterrence value of a battleship in protecting a convoy was dramatically illustrated when the German light battleships Scharnhorst and Gneisenau, mounting 11 in guns, came upon an eastbound British convoy in the North Atlantic on February 8, 1941. When the Germans detected the slow but well-protected battleship HMS Ramillies escorting the convoy, they f
Ship commissioning is the act or ceremony of placing a ship in active service, may be regarded as a particular application of the general concepts and practices of project commissioning. The term is most applied to the placing of a warship in active duty with its country's military forces; the ceremonies involved are rooted in centuries old naval tradition. Ship naming and launching endow a ship hull with her identity, but many milestones remain before she is completed and considered ready to be designated a commissioned ship; the engineering plant and electronic systems and multitudinous other equipment required to transform the new hull into an operating and habitable warship are installed and tested. The prospective commanding officer, ship's officers, the petty officers, seamen who will form the crew report for training and intensive familiarization with their new ship. Prior to commissioning, the new ship undergoes sea trials to identify any deficiencies needing correction; the preparation and readiness time between christening-launching and commissioning may be as much as three years for a nuclear powered aircraft carrier to as brief as twenty days for a World War II landing ship.
USS Monitor, of American Civil War fame, was commissioned less than three weeks after launch. Regardless of the type of ship in question, a vessel's journey towards commissioning in its nation's navy begins with a process known as sea trials. Sea trials take place some years after a vessel was laid down, mark the interim step between the completion of a ship's construction and its official acceptance for service with its nation's navy. Sea trials begin when the ship in question is floated out of its dry dock, at which time the initial crew for a ship will assume command of the vessel in question; the ship is sailed in littoral waters for the purpose of testing the design and other ship specific systems to ensure that they work properly and can handle the equipment that they will be using in the coming years. Tests done during this phase can include launching missiles from missile magazines, firing the ship's gun, conducting basic flight tests with rotary and fixed-wing aircraft that will be assigned to the ship in the future, various tests of the electronic and propulsion equipment.
During this phase of testing problems arise relating to the state of the equipment on the ship in question, which can result in the ship returning to the builder's shipyard to address the concerns in question. In addition to problems with a ship's arms and equipment, the sea trial phase a ship undergoes prior to commissioning can identify issues with the ship's design that may need to be addressed before it can be accepted into service with its nation's navy. During her sea trials in 1999 French Naval officials determined that the French aircraft carrier Charles de Gaulle was too short to safely operate the E2C Hawkeye, resulting in her return to the builder's shipyard for enlargement. After a ship has cleared its sea trial period, it will be accepted into service with its nation's navy. At this point, the ship in question will undergo a process of degaussing and/or deperming, which will vastly reduce the ship in question's magnetic signature. Once a ship's sea trials are completed plans for the actual commissioning ceremony will take shape.
Depending on the naval traditions of the nation in question, the commissioning ceremony may be an elaborately planned event with guests, the ship's future crew, other persons of interest in attendance, or the nation in question may forgo a ceremony and instead administratively place the ship in commission. At a minimum, on the day on which the ship in question is to be commissioned the crew will report for duty aboard the ship and the commanding officer will read through the orders given for the ship and its personnel. If the ship's ceremony is a public affair the Captain may make a speech to the audience, along with other VIPs as the ceremony dictates. Religious ceremonies, such as blessing the ship or the singing of traditional hymns or songs, may occur. Once a ship has been commissioned its final step toward becoming an active unit of the navy it now serves is to report to its home port and load or accept any remaining equipment. To decommission a ship is to terminate its career in service in the armed forces of a nation.
Unlike wartime ship losses, in which a vessel lost to enemy action is said to be struck, decommissioning confers that the ship has reached the end of its usable life and is being retired from a given country's navy. Depending on the naval traditions of the country in question, a ceremony commemorating the decommissioning of the ship in question may take place, or the vessel may be removed administratively with little to no fanfare; the term "paid off" is alternatively used in British Commonwealth contexts, originating in the age-of-sail practice of ending an officer's commission and paying crew wages once the ship completed its voyage. Ship decommissioning occurs some years after the ship was commissioned and is intended to serve as a means by which a vessel that has become too old or too obsolete can be retired with honor from the operating country's armed force. Decommissioning of the vessel may occur due to treaty agreements or for safety reasons (such as a ship's nuclear reactor and assoc
Oerlikon 20 mm cannon
The Oerlikon 20 mm cannon is a series of autocannons, based on an original German 20 mm Becker design that appeared early in World War I. It was produced by Oerlikon Contraves and others, with various models employed by both Allied and Axis forces during World War II, many versions still in use today. During World War I, the German industrialist Reinhold Becker developed a 20 mm caliber cannon, known now as the 20 mm Becker using the Advanced Primer Ignition blowback method of operation; this had a cyclic rate of fire of 300 rpm. It was used on a limited scale as an aircraft gun on Luftstreitkräfte warplanes, an anti-aircraft gun towards the end of that war; because the Treaty of Versailles banned further production of such weapons in Germany, the patents and design works were transferred in 1919 to the Swiss firm SEMAG based near Zürich. SEMAG continued development of the weapon, in 1924 had produced the SEMAG L, a heavier weapon that fired more powerful 20x100RB ammunition at a higher rate of fire, 350 rpm.
In 1924 SEMAG failed. The Oerlikon firm, named after the Zürich suburb of Oerlikon where it was based acquired all rights to the weapon, plus the manufacturing equipment and the employees of SEMAG. In 1927 the Oerlikon S was added to the existing product line; this fired a still larger cartridge to achieve a muzzle velocity of 830 m/s, at the cost of increased weight and a reduced rate of fire. The purpose of this development was to improve the performance of the gun as an anti-tank and anti-aircraft weapon, which required a higher muzzle velocity. An improved version known as the 1S followed in 1930. Three sizes of gun with their different ammunition and barrel length, but similar mechanisms, continued to be developed in parallel. In 1930 Oerlikon reconsidered the application of its gun in aircraft and introduced the AF and AL, designed to be used in flexible mounts, i.e. manually aimed by a gunner. The 15-round box magazine used by earlier versions of the gun was replaced by drum magazine holding 15 or 30 rounds.
In 1935 it made an important step by introducing a series of guns designed to be mounted in or on the wings of fighter aircraft. Designated with FF for Flügelfest meaning "wing-mounted", these weapons were again available in the three sizes, with designations FF, FFL and FFS; the FF fired a larger cartridge than the AF, 20x72RB, but the major improvement in these weapons was a significant increase in rate of fire. The FF weighed 24 kg and achieved a muzzle velocity of 550 to 600 m/s with a rate of fire of 520 rpm; the FFL of 30 kg fired a projectile at a muzzle velocity of 675 m/s with a rate of fire of 500 rpm. And the FFS, which weighed 39 kg, delivered a high muzzle velocity of 830 m/s at a rate of fire of 470 rpm. Apart from changes to the design of the guns for wing-mounting and remote control, larger drums were introduced as it would not be possible to exchange magazines in flight. For the FF series drum sizes of 45, 60, 75 and 100 rounds were available, but most users chose the 60-round drum.
The 1930s were a period of global re-armament, a number of foreign firms took licenses for the Oerlikon family of aircraft cannon. In France, Hispano-Suiza manufactured development of the FFS as the Hispano-Suiza HS.7 and Hispano-Suiza HS.9, for installation between the cylinder banks of its V-12 engines. In Germany, Ikaria further developed the FF gun as firing 20x80RB ammunition, and the Imperial Japanese Navy, after evaluating all three guns, ordered developments of the FF and FFL as the Type 99-1 and Type 99-2. The incorporation of the improvements of the FFS in a new anti-aircraft gun produced, in 1938, the Oerlikon SS. Oerlikon realized further improvements in rate of fire on the 1SS of 1942, the 2SS of 1945 which achieved 650 rpm. However, it was the original SS gun, adopted as anti-aircraft gun, being widely used by Allied navies during World War II; this gun used a 400-grain charge of IMR 4831 smokeless powder to propel a 2,000-grain projectile at 2,800 feet per second. The Oerlikon FF was installed as armament on some fighters of the 1930s, such as the Polish PZL P.24G.
Locally produced derivatives of the Oerlikon cannon were used much more extensively, on aircraft, on ships and on land. In the air, the Ikaria MG FF was used as armament on a number of German aircraft, of which the most famous is the Messerschmitt Bf 109; the Japanese Navy used their copy of the FF, designated the Type 99 Mark One cannon on a number of types including the Mitsubishi A6M Zero. In the war, they equipped fighters including the Zero with the Type 99 Mark Two, a version of the more powerful and faster-firing Oerlikon FFL; the French firm of Hispano-Suiza was a manufacturer of aircraft engines, it marketed the moteur-canon combination of its 12X and 12Y engines with a H. S.7 or H. S.9 cannon installed between the cylinder banks. The gun fired through the hollow propeller hub, this being elevated above the crankcase by the design of the gearing; such armament was installed on the Morane-Saulnier M. S.406 and some other types. Similar German installations of the MG FF were not successful.
The Oerlikon became best known in its naval applications. The Oerlikon was not looked upon favorably by the Royal Navy as a short-range anti-aircraft gun. All through 1937-1938 Lord Louis Mountbatten a Captain in the Royal Navy, waged a lone campaign within the Royal Navy to set up an unprejudiced trial for the Oerlikon 20 mm gun, but it was all in vain, it was not until the Commander-in-Chief of the Home Fleet, Admiral Sir Roger Backhouse, was appointed First Sea Lord tha