86-594: The Mark 54 lightweight torpedo (formerly known as lightweight hybrid torpedo , or LHT ) is a standard 12.75-inch (324 mm) anti-submarine warfare (ASW) torpedo used by the United States Navy . The Mark 54 was co-developed by Raytheon Integrated Defense Systems and the U.S. Navy under the U.S. Navy's Lightweight Hybrid Torpedo program in response to perceived problems with the extant Mark 50 and Mark 46 torpedoes. The Mk 50, having been developed to counter very high performance nuclear submarines such as
172-417: A 35–40 lb (16–18 kg) cone-shaped steel drum on a 5 ft (1.5 m) shaft, intended to be thrown at a submarine. Firing Lyddite shells, or using trench mortars , was tried. Use of nets to ensnare U-boats was also examined, as was a destroyer, HMS Starfish , fitted with a spar torpedo . To attack at set depths, aircraft bombs were attached to lanyards which would trigger their charges;
258-427: A blockaded area of water, but any ship can be inspected as soon as it is established that it is attempting to break the blockade. This inspection can occur inside the blockaded area or in international waters, but never inside the territorial waters of a neutral nation . A neutral ship must obey a request to stop for inspection from the blockading nation. If the situation so demands, the blockading nation can request that
344-625: A combination of sensor and weapon technologies, along with effective deployment strategies and sufficiently trained personnel. Typically, sophisticated sonar equipment is used for first detecting, then classifying, locating, and tracking a target submarine. Sensors are therefore a key element of ASW. Common weapons for attacking submarines include torpedoes and naval mines , which can both be launched from an array of air, surface, and underwater platforms. ASW capabilities are often considered of significant strategic importance, particularly following provocative instances of unrestricted submarine warfare and
430-462: A comparable WW2 submarine; in addition, they recharged their batteries using a snorkel and could complete a patrol without surfacing. This led to the introduction of longer-ranged forward-throwing weapons, such as Weapon Alpha , Limbo , RBU-6000 , and of improved homing torpedoes. Nuclear submarines , even faster still, and without the need to snorkel to recharge batteries, posed an even greater threat; in particular, shipborne helicopters (recalling
516-403: A device intended for countermining , a "dropping mine". At Admiral John Jellicoe 's request, the standard Mark II mine was fitted with a hydrostatic pistol (developed in 1914 by Thomas Firth & Sons of Sheffield) preset for 45 ft (14 m) firing, to be launched from a stern platform. Weighing 1,150 lb (520 kg), and effective at 100 ft (30 m), the "cruiser mine"
602-465: A fortress or city and the objective may not always be to conquer the area. A blockading power can seek to cut off all maritime transport from and to the blockaded country, although stopping all land transport to and from an area may also be considered a blockade. Blockades restrict the trading rights of neutrals, who must submit for inspection for contraband, which the blockading power may define narrowly or broadly, sometimes including food and medicine. In
688-410: A large role. The use of nuclear propulsion and streamlined hulls has resulted in submarines with high speed capability and increased maneuverability, as well as low "indiscretion rates" when a submarine is exposed on the surface. This has required changes both to the sensors and weapons used for ASW. Because nuclear submarines were noisy, there was an emphasis on passive sonar detection. The torpedo became
774-407: A large, modern submarine fleet, because all had fallen in the grip of Mahanian doctrine which held guerre de course could not win a war. At the beginning of the conflict, most navies had few ideas how to combat submarines beyond locating them with sonar and then dropping depth charges on them. Sonar proved much less effective than expected, and was no use at all against submarines operating on
860-703: A long tail boom (fixed-wing aircraft) or an aerodynamic housing carried on a deployable tow line (helicopters). Keeping the sensor away from the plane's engines and avionics helps eliminate interference from the carrying platform. At one time, reliance was placed on electronic warfare detection devices exploiting the submarine's need to perform radar sweeps and transmit responses to radio messages from home port. As frequency surveillance and direction finding became more sophisticated, these devices enjoyed some success. However, submariners soon learned not to rely on such transmitters in dangerous waters. Home bases can then use extremely low frequency radio signals, able to penetrate
946-642: A meeting with their American counterparts in June 1917. In October 1918, there was a meeting in Paris on "supersonics", a term used for echo-ranging, but the technique was still in research by the end of the war. The first recorded sinking of a submarine by depth charge was U-68 , sunk by Q-ship HMS Farnborough off County Kerry , Ireland 22 March 1916. By early 1917, the Royal Navy had also developed indicator loops which consisted of long lengths of cables lain on
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#17328731509411032-540: A military target. In such case, they are a war crime and potentially a crime against humanity . Although primitive naval blockades had been in use for millennia, they were limited by the time ships were able to stay at sea uninterruptedly. The first successful attempts at establishing a full naval blockade were made by the British Royal Navy during the Seven Years' War (1754–1763) against France . Following
1118-561: A ram with which to sink submarines, and U-15 was thus sunk in August 1914. During June 1915, the Royal Navy began operational trials of the Type D depth charge, with a 300 lb (140 kg) charge of TNT ( amatol , as TNT supplies became critical) and a hydrostatic pistol, firing at either 40 or 80 ft (12 or 24 m), and believed to be effective at a distance of 140 ft (43 m);
1204-466: A result, in the latter half of 1943, US subs were suddenly sinking Japanese ships at a dramatically higher rate, scoring their share of key warship kills and accounting for almost half of the Japanese merchant fleet. Japan's naval command was caught off guard; Japan had neither the anti-submarine technology or doctrine, nor the production capability to withstand a tonnage war of attrition , nor did she develop
1290-594: A semi-autonomous oceangoing unmanned naval vessel. Today some nations have seabed listening devices capable of tracking submarines. It is possible to detect man-made marine noises across the southern Indian Ocean from South Africa to New Zealand. Some of the SOSUS arrays have been turned over to civilian use and are now used for marine research. Several countries developed anti-submarine missiles including United States , Russia , China , South Korea , Japan and India . Anti-submarine missiles give flexibility in terms of
1376-560: A ship by an underwater vehicle are generally believed to have been during the American Revolutionary War , using what would now be called a naval mine but what was then referred to as a torpedo. Even so, various attempts to produce submarines had been made prior to this. In 1866, British engineer Robert Whitehead invented the first effective self-propelled torpedo, the eponymous Whitehead torpedo ; French and German inventions followed soon thereafter. The first submarine with
1462-499: A similar idea was a 16 lb (7.3 kg) guncotton charge in a lanyarded can; two of these lashed together became known as the Depth Charge Type A. Problems with the lanyards tangling and failing to function led to the development of a chemical pellet trigger as the Type B. These were effective at a distance of around 20 ft (6.1 m). Perhaps the best early concept arose in a 1913 RN Torpedo School report, describing
1548-706: A torpedo was Nordenfelt I built in 1884–1885, though it had been proposed earlier. By the outbreak of the Russo-Japanese War , all the large navies except the Germans had acquired submarines. Nevertheless, by 1904, all powers still defined the submarine as an experimental vessel and did not put it into operational use. There were no means to detect submerged U-boats, and attacks on them were limited at first to efforts to damage their periscopes with hammers. The Royal Navy torpedo establishment, HMS Vernon , studied explosive grapnel sweeps; these sank four or five U-boats in
1634-413: Is the act of actively preventing a country or region from receiving or sending out food , supplies , weapons , or communications , and sometimes people, by military force . A blockade differs from an embargo or sanction , which are legal barriers to trade rather than physical barriers. It is also distinct from a siege in that a blockade is usually directed at an entire country or region, rather than
1720-534: The R1 was the first ASW submarine. 211 of the 360 U-boats were sunk during the war, from a variety of ASW methods: This period saw the development of active sonar ( ASDIC ) and its integration into a complete weapons system by the British, as well as the introduction of radar . During the period, there was a great advance due to the introduction of electronics for amplifying, processing, and displaying signals. In particular,
1806-488: The Admiralty . To attack submerged boats, a number of anti-submarine weapons were derived, including the sweep with a contact-fused explosive. Bombs were dropped by aircraft and depth charge attacks were made by ships. Prior to the introduction of dedicated depth charge throwers, charges were manually rolled off the stern of a ship. The Q-ship , a warship disguised as a merchantman, was used to attack surfaced U-boats, while
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#17328731509411892-617: The Battle of Trafalgar . Until 1827, blockades, as part of economic warfare , were always a part of a war. This changed when France, Russia and Britain came to the aid of the Greek rebels against Turkey . They blockaded the Turkish-occupied coast, which led to the battle of Navarino . War was never declared, however, so it is considered the first pacific — i.e. peaceful — blockade. The first truly pacific blockade , involving no shooting at all,
1978-710: The Mark 32 surface vessel torpedo tubes or the vertical launch anti-submarine rocket (ASROC) systems, and also from most ASW aircraft, although they are slightly different lengths and weights. The P-8 Poseidon uses the High-Altitude Anti-Submarine Warfare Weapons Capability (HAAWC) GPS-guided glide kit to drop torpedoes from high altitude. The FY14 DOT&E report assessed the Mk 54 (BUG) torpedo as not operationally effective in its intended role: "During operationally challenging and realistic scenarios,
2064-613: The Royal Canadian Navy 's Halifax-class frigates , and the Royal Canadian Air Force 's CP-140 Aurora aircraft. The torpedoes are also planned to be deployed from the CH-148 maritime helicopters . On 17 May 2019, the U.S. State Department approved the sale worth US$ 387 Million (C$ 514 Million in 2019.) Under Canada's Industrial and Technological Benefits Policy, Canada negotiated an Offset agreement with Raytheon before signing
2150-637: The Second World War , the Allies developed a huge range of new technologies, weapons and tactics to counter the submarine danger. These included: Italian and German submarines operated in the Mediterranean on the Axis side while French and British submarines operated on the side of the Allies. The German Navy sent 62 U-boats to the Mediterranean; all were lost in combat or scuttled. German subs first had to pass through
2236-544: The Soviet Alfa class, was seen as too expensive to use against relatively slow conventional submarines. The older Mk 46, designed for open-ocean use, performed poorly in the littoral areas, where the Navy envisioned itself likely to operate in the future. The Mk 54 was created by combining the homing portion of the Mk 50 and the warhead and propulsion sections of the Mk 46, improved for better performance in shallow water, and with
2322-574: The Whiskey and Zulu classes. Britain also tested hydrogen peroxide fuels in Meteorite , Excalibur , and Explorer , with less success. To deal with these more capable submarines new ASW weapons were essential. This new generation of diesel electric submarine, like the Type XXI before it, had no deck gun and a streamlined hull tower for greater underwater speed, as well as more storage battery capacity than
2408-502: The Wolfpack achieved initial success, but became increasingly costly as more capable ASW aircraft were introduced. Technologies such as the Naxos radar detector gained only a temporary reprieve until detection apparatus advanced yet again. Intelligence efforts, such as Ultra , had also played a major role in curtailing the submarine threat and guiding ASW efforts towards greater success. During
2494-524: The blimps of World War I) have emerged as essential anti-submarine platforms. A number of torpedo carrying missiles such as ASROC and Ikara were developed, combining ahead-throwing capability (or longer-range delivery) with torpedo homing. Since the introduction of submarines capable of carrying ballistic missiles , great efforts have been made to counter the threat they pose; here, maritime patrol aircraft (as in World War II) and helicopters have had
2580-491: The postwar era, ASW continued to advance, as the arrival of nuclear submarines had rendered some traditional techniques less effective. The superpowers of the era constructed sizable submarine fleets, many of which were armed with nuclear weapons ; in response to the heightened threat posed by such vessels, various nations chose to expand their ASW capabilities. Helicopters , capable of operating from almost any warship and equipped with ASW apparatus, became commonplace during
2666-479: The "life and death" urgency in the Atlantic. However, US Vice Admiral Charles A. Lockwood pressured the ordnance department to replace the faulty torpedoes; famously when they initially ignored his complaints, he ran his own tests to prove the torpedoes' unreliability. He also cleaned out the "deadwood", replacing many cautious or unproductive submarine skippers with younger (somewhat) and more aggressive commanders. As
Mark 54 lightweight torpedo - Misplaced Pages Continue
2752-466: The "range recorder" was a major step that provided a memory of target position. Because the propellers of many submarines were extremely loud in the water (though it doesn't seem so from the surface), range recorders were able to gauge the distance from the U-boat by sound. This would allow mines or bombs around that area to be detonated. New materials for sound projectors were developed. Both the Royal Navy and
2838-526: The 1960s. Increasingly capable fixed-wing maritime patrol aircraft were also widely used, capable of covering vast areas of ocean. The Magnetic Anomaly Detector (MAD), diesel exhaust sniffers , sonobuoys and other electronic warfare technologies also became a staple of ASW efforts. Dedicated attack submarines , purpose-built to track down and destroy other submarines, became a key component as well. Torpedo carrying missiles, such as ASROC and Ikara , were another area of advancement. The first attacks on
2924-571: The 20th century, air power has also been used to enhance the effectiveness of blockades by halting air traffic within the blockaded airspace. Close patrol of hostile ports, in order to prevent naval forces from putting to sea, is also referred to as a blockade. When coastal cities or fortresses were besieged from the landward side, the besiegers would often blockade the seaward side as well. Most recently, blockades have sometimes included cutting off electronic communications by jamming radio signals and severing undersea cables . Blockades often result in
3010-652: The Allied merchant convoys and strategic shipping lanes to any degree that German U-boats did. One major advantage the Allies had was the breaking of the Japanese "Purple" code by the US, so allowing friendly ships to be diverted from Japanese submarines and allowing Allied submarines to intercept Japanese forces. In 1942 and early 1943, US submarines posed little threat to Japanese ships, whether warships or merchant ships. They were initially hampered by poor torpedoes, which often failed to detonate on impact, ran too deep, or even ran wild. As
3096-553: The British naval victory at Quiberon Bay , which ended any immediate threat of a major invasion of Britain , Britain established a close blockade on the French coast. This starved French ports of commerce, weakening France's economy. Admiral Edward Hawke took command of the blockading fleet off Brest and extended the blockade to cover the entire French Atlantic coast from Dunkirk to Bordeaux , and also to Marseilles on France's Mediterranean coast. The strategic importance of blockade
3182-463: The First World War. A similar approach featured a string of 70 lb (32 kg) charges on a floating cable, fired electrically; an unimpressed Admiral Edward Evans considered any U-boat sunk by it deserved to be. Another primitive technique of attacking submarines was the dropping of 18.5 lb (8.4 kg) hand-thrown guncotton bombs. The Lance Bomb was developed, also; this featured
3268-669: The Mk 54 (BUG) demonstrated below threshold performance and exhibited many of the same failure mechanisms observed during the FY 2004 initial operational testing". Shortfalls were also identified with the employing platforms’ tactics and tactical documentation, and interoperability problems with some platform fire control systems. In May 2019 Canada requested 425 Mk 54 lightweight torpedo conversion kits, plus ancillary training, exercise and maintenance spare parts. This procurement will allow Canada to upgrade its current inventory of Mk 46 torpedoes . The Mk 54 lightweight torpedoes are expected to be used on
3354-506: The Navy developed and introduced the Kyushu Q1W anti-submarine bomber into service in 1945. The Japanese depth charge attacks by its surface forces initially proved fairly unsuccessful against U.S. fleet submarines. Unless caught in shallow water, a U.S. submarine commander could normally escape destruction, sometimes using temperature gradients ( thermoclines ). Additionally, IJN doctrine emphasized fleet action, not convoy protection, so
3440-771: The Pacific, mainly against coastal shipping. In the immediate postwar period, the innovations of the late war U-boats were quickly adopted by the major navies. Both the United Kingdom and The United States studied the German Type XXI and used the information to modify WW2 fleet boats, the US with the GUPPY program and the UK with the Overseas Patrol Submarines Project. The Soviets launched new submarines patterned on Type XXIs,
3526-534: The Security Council to ensure the maintenance of international peace. According to the not ratified document San Remo Manual on International Law Applicable to Armed Conflicts at Sea, 12 June 1994, a blockade is a legal method of warfare at sea but is governed by rules. The manual describes what can never be contraband. The blockading nation is free to select anything else as contraband in a list, which it must publish. The blockading nation typically establishes
Mark 54 lightweight torpedo - Misplaced Pages Continue
3612-621: The Type D*, with a 120 lb (54 kg) charge, was offered for smaller ships. In July 1915, the British Admiralty set up the Board of Invention and Research (BIR) to evaluate suggestions from the public as well as carrying out their own investigations. Some 14,000 suggestions were received about combating submarines. In December 1916, the RN set up its own Anti-Submarine Division (ASD), from which came
3698-409: The U.S. Navy fitted their destroyers with active sonars. In 1928, a small escort ship was designed and plans made to arm trawlers and to mass-produce ASDIC sets. Several other technologies were developed; depth sounders that allowed measurement by moving ships were a new innovation, along with a greater appreciation of the properties of the ocean that affected sound propagation. The bathythermograph
3784-433: The US submarine menace was slight in the beginning, Japanese commanders became complacent and as a result did not invest heavily into ASW measures or upgrade their convoy protection to any degree to what the Allies in the Atlantic did. Often encouraged by the Japanese not placing a high priority on the Allied submarine threat, US skippers were relatively complacent and docile compared to their German counterparts, who understood
3870-548: The addition of commercial off-the-shelf (COTS) technology to further reduce costs. It shares much of the software and computer hardware of the Mk 48 ADCAP heavy torpedo , based around a custom PowerPC 603e microprocessor. Developmental testing began in July 1999, and a successful critical design review was completed in November 1999. In April 2003, Raytheon was awarded a sole source contract for
3956-487: The best ships and crews went elsewhere. Moreover, during the first part of the war, the Japanese tended to set their depth charges too shallow, unaware U.S. submarines could dive below 150 feet (45m). Unfortunately, this deficiency was revealed in a June 1943 press conference held by U.S. Congressman Andrew J. May , and soon enemy depth charges were set to explode as deep as 250 feet (76m). Vice Admiral Charles A. Lockwood , COMSUBPAC , later estimated May's revelation cost
4042-519: The early part of the Pacific War, Japanese subs scored several tactical victories, three successful torpedo strikes on the US fleet carriers Yorktown (CV-5), USS Saratoga and USS Wasp (CV-7), The Saratoga survived the attack and was repaired, while the Yorktown and Wasp were both abandoned and scuttled as a result of the attack. The USS North Carolina (BB-55) received a single torpedo in
4128-399: The end of World War II . While dipping hydrophones appeared before war's end, the trials were abandoned. Seaplanes and airships were also used to patrol for submarines. A number of successful attacks were made, but the main value of air patrols was in driving the U-boat to submerge, rendering it virtually blind and immobile. However, the most effective anti-submarine measure was
4214-440: The endurance of small submarines. Previously the emphasis had been largely on deep water operation but this has now switched to littoral operation where ASW is generally more difficult. There are a large number of technologies used in modern anti-submarine warfare: In modern times forward looking infrared (FLIR) detectors have been used to track the large plumes of heat that fast nuclear-powered submarines leave while rising to
4300-517: The fact a submarine of the day was often on the surface for a range of reasons, such as charging batteries or crossing long distances. The first approach to protect warships was chainlink nets strung from the sides of battleships , as defense against torpedoes . Nets were also deployed across the mouth of a harbour or naval base to stop submarines entering or to stop torpedoes of the Whitehead type fired against ships. British warships were fitted with
4386-591: The final deal in order to leverage jobs and economic benefits in Canada. Anti-submarine warfare Anti-submarine warfare ( ASW , or in the older form A/S ) is a branch of underwater warfare that uses surface warships , aircraft , submarines , or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are typically carried out to protect friendly shipping and coastal facilities from submarine attacks and to overcome blockades . Successful ASW operations typically involved
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#17328731509414472-497: The helicopter has been used solely for sensing and rocket delivered torpedoes used as the weapon. Surface ships continue to be an important ASW platform because of their endurance, now having towed array sonars. Submarines are the main ASW platform because of their ability to change depth and their quietness, which aids detection. In early 2010 DARPA began funding the ACTUV programme to develop
4558-405: The highly defended Straits of Gibraltar , where nine were sunk, and a similar number damaged so severely they had to limp back to base. The Mediterranean is calmer than the Atlantic, which made escape for U-boats more difficult and was ringed with Allied air bases. Similar ASW methods were used as in the Atlantic but an additional menace was the use by Italians of midget submarines. Operating under
4644-637: The introduction of submarine-launched ballistic missiles , which greatly increased the lethality of submarines. At the beginning of the twentieth century, ASW techniques and submarines themselves were primitive. During the First World War , submarines deployed by Imperial Germany proved themselves to be a capable threat to shipping, being capable of striking targets even out in the North Atlantic Ocean. Accordingly, multiple nations embarked on research into devising more capable ASW methods, resulting in
4730-555: The introduction of escorted convoys , which reduced the loss of ships entering the German war zone around the British Isles from 25% to less than 1%. The historian Paul E. Fontenoy summarised the situation as: "[t]he convoy system defeated the German submarine campaign ." A major contributing factor was the interception of German submarine radio signals and breaking of their code by Room 40 of
4816-457: The introduction of practical depth charges and advances in sonar technology; the adoption of the convoy system also proved to be a decisive tactic. After a lull in progress during the interwar period, the Second World War would see submarine warfare and ASW alike advance rapidly, particularly during the critical Battle of the Atlantic , during which Axis submarines sought to prevent Britain from effectively importing supplies. Techniques such as
4902-502: The largest and longest range vessels of their type and were armed with the Type 95 torpedo . However, they ended up having little impact, especially in the latter half of the war. Instead of commerce raiding like their U-boat counterparts, they followed the Mahanian doctrine, serving in offensive roles against warships, which were fast, maneuverable and well-defended compared to merchant ships. In
4988-503: The launch platform. India developed supersonic long range anti-submarine missile called SMART . The missile helps to deliver torpedo 643 km away. In World War I , eight submarines were sunk by friendly fire and in World War II nearly twenty were sunk this way. Still, IFF has not been regarded a high concern before the 1990s by the US military as not many other countries possess submarines . Blockade A blockade
5074-409: The main weapon (though nuclear depth charges were developed). The mine continued to be an important ASW weapon. In some areas of the ocean, where land forms natural barriers, long strings of sonobuoys, deployed from surface ships or dropped from aircraft, can monitor maritime passages for extended periods. Bottom mounted hydrophones can also be used, with land based processing. A system like this SOSUS
5160-587: The most difficult form of blockade to implement. Difficulties arise because the blockading ships must remain continuously at sea, exposed to storms and hardship, usually far from any support, and vulnerable to sudden attack from the blockaded side, whose ships may stay safe in harbor until they choose to come out. In a distant blockade, the blockaders stay well away from the blockaded coast and try to intercept any ships going in or out. This may require more ships on station, but they can usually operate closer to their bases, and are at much less risk from enemy raids. This
5246-473: The navy as many as ten submarines and 800 crewmen. Much later in the war, active and passive sonobuoys were developed for aircraft use, together with MAD devices. Toward the end of the war, the Allies developed better forward-throwing weapons, such as Mousetrap and Squid , in the face of new, much better German submarines, such as the Type XVII and Type XXI . British and Dutch submarines also operated in
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#17328731509415332-472: The ocean's surface, to reach submarines wherever they might be. The military submarine is still a threat, so ASW remains a key to obtaining sea control. Neutralizing the SSBN has been a key driver and this still remains. However, non-nuclear-powered submarines have become increasingly important. Though the diesel-electric submarine continues to dominate in numbers, several alternative technologies now exist to enhance
5418-459: The organizations needed (unlike the Allies in the Atlantic). Japanese antisubmarine forces consisted mainly of their destroyers, with sonar and depth charges. However, Japanese destroyer design, tactics, training, and doctrine emphasized surface nightfighting and torpedo delivery (necessary for fleet operations) over anti-submarine duties. By the time Japan finally developed a destroyer escort , which
5504-684: The production of the Mk 54. Full rate production began in October 2004. In March 2010 the Fifth Fleet requested improvements in the Mk 54's performance against diesel-electric submarines via an Urgent Operational Need Statement (UONS). This led to a software Block Upgrade (BUG) program which began testing in August 2011 and which continues, having been criticised by the Director, Operational Test and Evaluation (DOT&E) for using unrealistic proxies for threat submarines. The Mk 54 can be fired from surface ships via
5590-632: The same attack with the USS Wasp, causing it to miss critical naval actions of the Guadalcanal campaign. Once the US was able to ramp up construction of destroyers and destroyer escorts , as well as bringing over highly effective anti-submarine techniques learned from the British from experiences in the Battle of the Atlantic , they would take a significant toll on Japanese submarines, which tended to be slower and could not dive as deep as their German counterparts. Japanese submarines, in particular, never menaced
5676-428: The same clear-water conditions in the Mediterranean – such that British submarines were painted dark blue on their upper surfaces to make them less visible from the air when submerged at periscope depth – the Royal Navy, mostly operating from Malta , lost 41 submarines to the opposing German and Italian forces, including HMS Upholder and HMS Perseus . Japanese submarines pioneered many innovations, being some of
5762-514: The seabed to detect the magnetic field of submarines as they passed overhead. At this stage, they were used in conjunction with controlled mines which could be detonated from a shore station once a 'swing' had been detected on the indicator loop galvanometer . Indicator loops used with controlled mining were known as 'guard loops'. By July 1917, depth charges had developed to the extent that settings of between 50–200 ft (15–61 m) were possible. This design would remain mainly unchanged through
5848-476: The ship divert to a known place or harbour for inspection. If the ship does not stop, then the ship is subject to capture. If people aboard the ship resist capture, they can be lawfully attacked. Whether or not a blockade was seen as lawful depended on the laws of the nations whose trade was influenced by the blockade. The Brazilian blockade of Río de la Plata in 1826 during the Cisplatine War , for instance,
5934-589: The ships actually monitoring the enemy submarine. Submerged submarines are generally blind to the actions of a patrolling aircraft until it uses active sonar or fires a weapon, and the aircraft's speed allows it to maintain a fast search pattern around the suspected contact. Increasingly anti-submarine submarines, called attack submarines or hunter-killers, became capable of destroying, particularly, ballistic missile submarines. Initially these were very quiet diesel-electric propelled vessels but they are more likely to be nuclear-powered these days. The development of these
6020-472: The starvation of the civilian population, notably during the blockade of Germany during World War I and the blockade of Biafra during the Nigerian Civil War . According to modern international law, blockades are an act of war. When used as a part of an effort to starve the civilian population, they are illegal as part of a war of aggression or when used against a civilian population, instead of
6106-408: The successive generations of Allied airborne radar. The first generation of Allied airborne radar used a 1.7 meter wavelength and had a limited range. By the second half of 1942 the " Metox " radar detector was used by U-boats to give some warning from airborne attack. During 1943, the Allies began to deploy aircraft equipped with new cavity magnetron-based 10-centimeter wavelength radar (ASV III), which
6192-494: The surface, as U-boats routinely did at night. The Royal Navy had continued to develop indicator loops between the wars but this was a passive form of harbour defense that depended on detecting the magnetic field of submarines by the use of long lengths of cable lain on the floor of the harbour. Indicator loop technology was quickly developed further and deployed by the US Navy in 1942. By then, there were dozens of loop stations around
6278-609: The surface. FLIR devices are also used to see periscopes or snorkels at night whenever a submariner might be incautious enough to probe the surface. Satellites have been used to image the sea surface using optical and radar techniques. Fixed-wing aircraft, such as the P-3 Orion & Tu-142 provide both a sensor and weapons platform similar to some helicopters like the Sikorsky SH-60 Seahawk , with sonobuoys and/or dipping sonars as well as aerial torpedoes . In other cases
6364-491: The term "Asdic", but relations with the BIR were poor. After 1917, most ASW work was carried out by the ASD. In the U.S., a Naval Consulting Board was set up in 1915 to evaluate ideas. After American entry into the war in 1917, they encouraged work on submarine detection. The U.S. National Research Council , a civilian organization, brought in British and French experts on underwater sound to
6450-513: The world. Sonar was far more effective and loop technology for ASW purposes was discontinued shortly after the conflict's end. The use and improvement of radar technology was one of the most important elements in the fight against submarines. Locating submarines was the first step in being able to defend against and destroy them. Throughout the war, Allied radar technology was much better than their German counterparts. German U-boats struggled to have proper radar detection capabilities and keep up with
6536-506: Was almost impossible prior to the 16th century due to the nature of the ships used. A loose blockade is a close blockade where the blockading ships are withdrawn out of sight from the coast (behind the horizon) but no farther. The object of loose blockade is to lure the enemy into venturing out but to stay close enough to strike. British admiral Horatio Nelson applied a loose blockade at Cádiz in 1805. The Franco-Spanish fleet under Pierre-Charles Villeneuve then came out, resulting in
6622-518: Was also a potential hazard to the dropping ship. During the First World War , submarines were a major threat. They operated in the Baltic, North Sea, Black Sea and Mediterranean as well as the North Atlantic. Previously, they had been limited to relatively calm and protected waters. The vessels used to combat them were a range of small, fast surface ships using guns and good luck. They mainly relied on
6708-413: Was considered lawful according to British law but unlawful according to French and American law. The latter two countries announced they would actively defend their ships against Brazilian blockaders, while Britain was forced to steer for a peaceful solution between Brazil and Argentina . Blockades depend on four general factors Blockade running is the practice of delivering cargo (food, for example) to
6794-526: Was deployed by the US in the GIUK gap and other strategically important places. Airborne ASW forces developed better bombs and depth charges , while for ships and submarines a range of towed sonar devices were developed to overcome the problem of ship-mounting. Helicopters can fly courses offset from the ships and transmit sonar information to their combat information centres . They can also drop sonobuoys and launch homing torpedoes to positions many miles away from
6880-674: Was invented in 1937, which became a common fixture amongst ASW ships within only a few years. There were relatively few major advances in weapons during the period; however, the performance of torpedoes continued to improve. During the Second World War , the submarine menace revived, threatening the survival of island nations like Britain and Japan which were particularly vulnerable because of their dependence on imports of food, oil, and other vital war materials. Despite this vulnerability, little had been done to prepare sufficient anti-submarine forces or develop suitable new weapons. Other navies were similarly unprepared, even though every major navy had
6966-508: Was more economical and better suited to convoy protection, it was too late; coupled to incompetent doctrine and organization, it could have had little effect in any case. Late in the war, the Japanese Army and Navy used Magnetic Anomaly Detector (MAD) gear in aircraft to locate shallow submerged submarines. The Japanese Army also developed two small aircraft carriers and Ka-1 autogyro aircraft for use in an antisubmarine warfare role, while
7052-400: Was repeated in World War II . Naval strategic thinkers, such as Sir Julian Corbett and Alfred Thayer Mahan , wrote that naval conflicts were won primarily by decisive battles, but also by blockade. A close blockade entails placing warships within sight of the blockaded coast or port, to ensure the immediate interception of any ship entering or leaving. It is both the most effective and
7138-710: Was shown during the French Revolutionary Wars and Napoleonic Wars , when the Royal Navy successfully blockaded France, leading to major economic disruptions. The Union blockade of southern ports was a major factor in the American Civil War . During World War I , the Allies blockaded the Central Powers , depriving them of food and other strategic materials. Germany's attempted U-boat blockade caused some shortages in Britain, but ultimately failed. This outcome
7224-582: Was strongly influenced by the duel between HMS Venturer and U-864 . A significant detection aid that has continued in service is the Magnetic Anomaly Detector (MAD), a passive device. First used during the Second World War, MAD uses the Earth's magnetosphere as a standard, detecting anomalies caused by large metallic vessels, such as submarines. Modern MAD arrays are usually contained in
7310-597: Was the British blockade of the Republic of New Granada in 1837, established to compel New Granada to release an imprisoned British consul. Since 1945, the United Nations Security Council determines the legal status of blockades and by article 42 of the UN Charter , the council can also apply blockades. The UN Charter allows for the right of self-defense but requires that this must be immediately reported to
7396-600: Was undetectable by "Metox", in sufficient numbers to yield good results. Eventually the "Naxos" radar detector was fielded that could detect 10-cm wavelength radar, but it had a very short range and only gave a U-boat limited time to dive. Between 1943 and 1945, radar equipped aircraft would account for the bulk of Allied kills against U-boats. Allied anti-submarine tactics developed to defend convoys (the Royal Navy 's preferred method), aggressively hunt down U-boats (the U.S. Navy approach), and to divert vulnerable or valuable ships away from known U-boat concentrations. During
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