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Encyclopedia > Anti submarine warfare

If you were searching for A/S, you might have meant aksjeselskap, a Norwegian stock company form. An aksjeselskap is the Norwegian term for a stock-based corporation. ...


Anti-submarine warfare (ASW or in older forms A/S) is a branch of naval warfare that uses surface warships, aircraft or other submarines to find, track and then damage or destroy enemy submarines. Naval warfare is combat in and on seas and oceans. ... Diagrams of first and third rate warships, England, 1728 Cyclopaedia. ... An Airbus A380, currently the worlds largest airliner An aircraft is any vehicle or craft capable of atmospheric flight. ... German UC-1 class World War I submarine A model of Gunter Priens Unterseeboot 47 (U-47), German WWII Type VII diesel-electric hunter-killer (SSK) submarine Inside of the Argonaute, showing the typical obstructed, tiny space of a post-WWII diesel attack submarine. ... German UC-1 class World War I submarine A model of Gunter Priens Unterseeboot 47 (U-47), German WWII Type VII diesel-electric hunter-killer (SSK) submarine Inside of the Argonaute, showing the typical obstructed, tiny space of a post-WWII diesel attack submarine. ...


Like many forms of warfare, successful anti-submarine warfare depends on a mix of superior technology, experience and luck. For other uses of War, see War (disambiguation). ...

Contents

Development of anti-submarine warfare

World War I

During the First World War submarines were a new menace. 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 that used guns and good luck. They mainly relied on the fact that a submarine of the day was often on the surface for a range of reasons, such as charging the batteries or crossing long distances at a higher speed. The first depth charges for attacking submarines at depth were used. The first approach to protect warships with chainlink nets strung from the sides of battleships would protect against torpedoes fired from submarines. Nets were also deployed across the mouth of a harbour or naval base to stop submarines entering or to stop torpedoes that were fired against ships. The hydrophone, an underwater microphone, was used to listen for submarines; the German U-boat, UC-3, was sunk with the aid of hydrophone on April 23 1916. The first sonars were deployed in 1916. By early 1917 the Royal Navy had also developed indicator loops which consisted of long lengths of cables lain on 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 a 'guard loops'. Combatants Allied Powers: France Italy Russia Serbia United Kingdom United States Central Powers: Austria-Hungary Bulgaria Germany Ottoman Empire Commanders Ferdinand Foch Georges Clemenceau Victor Emmanuel III Luigi Cadorna Nicholas II Aleksei Brusilov Herbert Henry Asquith Douglas Haig John Jellicoe Woodrow Wilson John Pershing Wilhelm II Paul von Hindenburg Reinhard... A gun is a common name given to a device that fires high-velocity projectiles. ... Depth Charge used by U.S. Navy later in World War II The depth charge is the oldest anti-submarine weapon. ... HMS Victory in 1884 Battleship was the name given to the most powerfully gun-armed and most heavily armored classes of warships built between the 15th and 20th centuries. ... A modern torpedo, historically called a locomotive torpedo, is a self-propelled projectile that (after being launched above or below the water surface) operates underwater and is designed to detonate on contact or in proximity to a target. ... U-boat is also a nickname for some diesel locomotives built by GE; see List of GE locomotives October 1939. ... April 23 is the 113th day of the year in the Gregorian Calendar (114th in leap years). ... // The F70 type frigates (here, La Motte-Picquet) are fitted with VDS (Variable Depth Sonar) type DUBV43 or DUBV43C tugged sonars SONAR (SOund Navigation And Ranging) â€” or sonar â€” (the British used Anti-Submarine Detection Investigation Committee (ASDIC) until 1948) is a technique that uses sound propagation under water to navigate...


World War II

Officers on the bridge of a destroyer on convoy escort duties keep a sharp look out for enemy submarines during the Battle of the Atlantic, October 1941
Officers on the bridge of a destroyer on convoy escort duties keep a sharp look out for enemy submarines during the Battle of the Atlantic, October 1941

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, despite the fact that every major navy had a large, modern submarine fleet. Image File history File links Officers_on_the_bridge. ... Image File history File links Officers_on_the_bridge. ... Battle of the Atlantic can refer to either of two naval campaigns, depending on context: World War I - First Battle of the Atlantic World War II - Second Battle of the Atlantic A Third Battle of the Atlantic was envisioned to be be part of any Third World War that arose... Combatants Major Allied powers: United Kingdom Soviet Union United States Republic of China and others Major Axis powers: Nazi Germany Italy Japan and others Commanders Winston Churchill Joseph Stalin Franklin Roosevelt Harry Truman Chiang Kai-Shek Adolf Hitler Benito Mussolini Hideki Tojo Casualties Military dead: 17,000,000 Civilian dead...

A depth charge being loaded onto a depth charge thrower on board the corvette HMS Dianthus, 14 August 1942
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A depth charge being loaded onto a depth charge thrower on board the corvette HMS Dianthus, 14 August 1942

At the beginning of the war, most navies had few ideas how to combat submarines beyond locating them with sonar and then dropping depth charges on them. But sonar proved much less effective than expected, and was no use at all against submarines operating on the surface at night. The Royal Navy had continued to develop indicator loops between the wars but this was a passive form of harbour defence 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 the world. Sonar was far more effective and loop technology died straight after the war. Depth Charge used by U.S. Navy later in World War II The depth charge is the oldest anti-submarine weapon. ... Depth Charge used by U.S. Navy later in World War II The depth charge is the oldest anti-submarine weapon. ...


Allied anti-submarine tactics developed to defend convoys, aggressively hunt down U-boats and to divert vulnerable or valuable ships away from known U-boat concentrations. The development of the steam ironclad firing explosive shells in the mid 19th century rendered sailing tactics obsolete. ... A convoy is a group of vehicles or ships traveling together for mutual support. ... U-boat is also a nickname for some diesel locomotives built by GE; see List of GE locomotives October 1939. ...


During the Second World War, the Allies developed a huge range of new technologies, weapons and tactics to counter the submarine danger. These included: Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km into the air. ...

Hedgehog, a 24 barrelled anti-submarine mortar, mounted on the forecastle of the destroyer HMS Westcott
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Hedgehog, a 24 barrelled anti-submarine mortar, mounted on the forecastle of the destroyer HMS Westcott
  • The development of forward-throwing anti-submarine weapons such as the hedgehog and the squid.
  • High frequency direction finding (HF/DF) to pinpoint the location of an enemy submarine from its radio transmissions.
  • The introduction of seaborne radar.
  • Air raids on the German U-boat bases at Brest and La Rochelle.
  • Long-range aircraft patrols to find German U-boats and either sink them or force them to submerge and lose contact with the convoy.
  • Airborne radar.
  • Torpedoes active countermeasures such as Foxer acoustic decoy.
  • The Leigh light airborne searchlight which was used in conjunction with airborne radar to surprise and attack enemy submarines on the surface at night.
  • Larger convoys, which allowed more escorts to be allocated to each convoy.
  • The formation of support groups of escort ships that could be sent to reinforce the defence of convoys under attack. Free from the obligation to remain with the convoys, support groups could continue hunting a submerged submarine until its batteries and air supplies were exhausted and it was forced to surface.
A Leigh Light used for spotting U-boats on the surface at night fitted to a Liberator aircraft of Royal Air Force Coastal Command, 26 February 1944
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A Leigh Light used for spotting U-boats on the surface at night fitted to a Liberator aircraft of Royal Air Force Coastal Command, 26 February 1944
A Vought SB2U scout bomber from USS Ranger (CV-4) flies anti-submarine patrol over the Convoy WS12, en route to Capetown, 27 November 1941
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A Vought SB2U scout bomber from USS Ranger (CV-4) flies anti-submarine patrol over the Convoy WS12, en route to Capetown, 27 November 1941

In the air many different aircraft from lighter-than-air airships to four-engined seaplanes and land-planes were used. Some of the more successful anti-submarine aircraft were the Lockheed Ventura, PBY Catalina, Consolidated B-24 Liberator, Short Sunderland and Vickers Wellington. A convoy is a group of vehicles or ships traveling together for mutual support. ... French steam corvette Dupleix (1856-1887) Canadian corvettes on antisubmarine convoy escort duty during World War II. A corvette is a small, maneuverable, lightly armed warship, smaller than a frigate but larger than a coastal patrol craft. ... For the bird, see Frigatebird. ... A Destroyer Escort (DE) is classification for a small, comparatively slower warship designed to be used to escort convoys of merchant marine ships, primarily of the United States Navy in WWII. It is usually employed primarily for anti-submarine warfare, but also some protection against aircraft and smaller attack vessels... The escort aircraft carrier or escort carrier, was a small aircraft carrier developed by the Royal Navy in the early part of World War II to deal with the U-boat crisis of the Battle of the Atlantic. ... Image File history File links Hedgehog_anti-submarine_mortar. ... Image File history File links Hedgehog_anti-submarine_mortar. ... Hedgehog anti-submarine weapon An anti-submarine weapon developed by the Royal Navy during World War II, the Hedgehog was deployed on convoy escort warships such as destroyers to supplement the depth charge. ... Squid was a World War II ship-mounted anti-submarine weapon. ... This long range RADAR antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll[1]. RADAR is a system that uses radio waves to detect, determine the direction and distance and/or speed... Location within France Brest, at the tip of Brittany Brest is a city in the Bretagne région, north-west France, sous-préfecture of the Finistère département. ... La Rochelle is a town and commune of western France, and a seaport on the Atlantic Ocean (population 76,584 in 1999). ... Foxer, was the codename for a British built acoustic decoy, used to confuse German acoustic homing torpedoes like the G7es torpedo during the Second World War. ... The Leigh Light (abbreviated L/L) was a British World War II era anti submarine device used in the Second Battle of the Atlantic. ... This long range RADAR antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll[1]. RADAR is a system that uses radio waves to detect, determine the direction and distance and/or speed... The Leigh Light (abbreviated L/L) was a British World War II era anti submarine device used in the Second Battle of the Atlantic. ... Royal Canadian Air Force B-24 Liberator The Consolidated B-24 Liberator was produced in greater numbers than any other American combat aircraft, and was used by most of the Allied air forces in World War II. Designed as a heavy bomber, it served with distinction not only in that... Vought is the name of several related aerospace firms. ... Lockheed PV-1 Ventura The Lockheed Ventura was a bomber and patrol aircraft of World War II, used by American and British forces in several guises. ... PBY Catalina was the United States Navy designation for an American and Canadian-built flying boat of the 1930s and 1940s. ... Royal Canadian Air Force B-24 Liberator The Consolidated B-24 Liberator was produced in greater numbers than any other American combat aircraft, and was used by most of the Allied air forces in World War II. Designed as a heavy bomber, it served with distinction not only in that... The S.25 Sunderland was a flying boat patrol bomber developed for the Royal Air Force by Short Brothers, first flown on 16 October 1937. ... The Vickers Wellington was a twin-engine, medium bomber designed in the mid-1930s at Brooklands in Weybridge, Surrey, by Vickers-Armstrongs Chief Designer, R.K. Pierson. ...


The provision of seaborne air cover was essential. At first, the British developed temporary solutions such as merchant aircraft carriers and CAM ships. These were superseded by mass-produced, relatively cheap escort carriers built by the United States and operated by the US Navy and by the Royal Navy. Merchant aircraft carriers (MAC) were minimal aircraft carriers used during World War II by Great Britain and Holland as an emergency measure until the United States-built escort carriers became available. ... A CAM ship was a World War II-era British merchant ship used in convoys as a cheap emergency solution to the shortage of escort carriers. ... The escort aircraft carrier or escort carrier, was a small aircraft carrier developed by the U.S. Navy in the early part of World War II to deal with the U-boat crisis of the Battle of the Atlantic. ...


At this point there was a significant difference in the tactics of the two navies and criticism was aimed at the British. The Americans favoured aggressive hunter-killer tactics using escort carriers on search and destroy patrols, whereas the British preferred to use their escort carriers to defend the convoys directly. The American view was that this tactic did little to reduce or contain U-boat numbers. In the event, the tactics were complementary, suppressing and destroying U-boats.


The critical Allied advantage was provided by the breaking of German naval codes (information gathered this way was dubbed Ultra) at Bletchley Park in England. This enabled the tracking of U-boat packs to allow convoy re-routings: however, whenever codes changed, convoy losses rose significantly. Ultra (sometimes capitalized ULTRA) was the name used by the British for intelligence resulting from decryption of German communications in World War II. The term eventually became the standard designation in both Britain and the United States for all intelligence from high-level cryptanalytic sources. ... During World War II, codebreakers at Bletchley Park solved messages from a large number of Axis code and cipher systems, including the German Enigma machine. ...


German sub sinkings were significantly increased after Allied forces began combining hunter-killer tactics with newly-developed anti-submarine weapons such as the Hedgehog anti-submarine mortar and the FIDO (Mk 24 'mine') air-dropped homing torpedo. An Anti-submarine weapon is any weapon system designed explicitly to attack and destroy enemy submarines and other underwater devices. ... The Mark 24 FIDO Torpedo was a US air-dropped passive acoustic homing anti-submarine torpedo used during the Second World War against German and Japanese submarines. ...


In the Pacific, Japanese antisubmarine forces often found themselves overmatched when trying to defend both naval ships and merchant shipping from attacks by U.S. and Allied submarines. The primary weapon of attack continued to be the depth charge, dropped from aircraft or deployed by surface ships. Japanese sub detection gear was not as advanced as that of some other nations. The primary Japanese anti-submarine weapon for most of WWII was the depth charge, and 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 dive to escape destruction, sometimes using temperature gradient barriers to escape pursuit. Additionally, during the first part of the war, the Japanese tended to set their depth charges too shallow, unaware that U.S. submarines could dive below 150 feet.


Unfortunately, the deficiencies of Japanese depth-charge tactics were revealed in a June 1943 press conference held by U.S. Congressman Andrew J. May, a member of the House Military Affairs Committee who had visited the Pacific theater and received many confidential intelligence and operational briefings. At the press conference, May revealed that American submarines had a high survivability because Japanese depth charges were fused to explode at too shallow a depth, typically 100 feet (because Japanese forces believed U.S. subs did not normally exceed this depth). Various press associations sent this story over their wires, and many newspapers, including one in Honolulu, thoughtlessly published it. Soon enemy depth charges were rearmed to explode at a more effective depth of 250 feet. Vice Admiral Charles A. Lockwood, commander of the U.S. submarine fleet in the Pacific, later estimated that May's revelation cost the navy as many as ten submarines and 800 crewmen.[1][2] Andrew Jackson May (June 24, 1875—September 6, 1959) was a Kentucky attorney and influential New Deal-era politician, best known for his central role in the May Incident. ...


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. A RNZAF P-3K Orion; the magnetic anomaly dectector protrudes from the tail to minimise interference from the aircrafts avionics. ... Modern Autogyro, ELA-07, Casarrubios del Monte Airfield, Spain, 2004. ...


Much later in the war, active and passive sonobuoys were developed for aircraft use. Sonarbuoy loaded on aircraft A sonobuoy (a portmanteau of sonar and buoy) is a relatively small (typically 4 7/8 inches, or ~124 mm, in diameter and 36 inches, or ~914 mm, long) expendable sonar system that is dropped/ejected from aircraft or ships conducting anti-submarine warfare or underwater...


Post-war

Since the introduction of submarines capable of carrying ballistic missiles, great efforts have been made to counter the threat they pose. In particular, the helicopter has emerged as a prime anti-submarine platform. Polish missile wz. ... The Bell 206 of Canadian Helicopters Robinson Helicopter Company (USA) R44, a four seat development of the R22 A helicopter is an aircraft which is lifted and propelled by one or more horizontal rotors. ...


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.


Seaborne forces developed better bombs and depth charges and a range of towed sonar devices to overcome the problem of ship-mounting that required ships to pass directly over the attacked submarine. Helicopters can fly courses offset from the ships and transmit sonar information to their combat information centre. They can also drop sonobuoys and launch homing torpedoes to positions many miles away from 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. The Massive Ordnance Air Blast (MOAB) bomb, also known as Mother Of All Bombs, produced in the United States. ... Depth Charge used by U.S. Navy later in World War II The depth charge is the oldest anti-submarine weapon. ... A Combat Information Center (CIC), or Action Information Center (AIC) is the tactical center of a warship, manned and equipped to collect, present, manage, evaluate and disseminate information for the use of the embarked flag officer, commanding officer, and control agencies. ...


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. A Hunter Killer is a light weight military submarine class used for fighting sea vehicles. ... Polish missile wz. ...


A significant detection aid that has continued in service is the Magnetic Anomaly Detector (MAD), a passive device. First used in World War II, the 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 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 that exploited the submarine's need to perform radar sweeps and to 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 that can penetrate the ocean's surface to reach submarines wherever they might be. Electronic warfare (EW) has three main components: Electronic Attack (EA) This is the active use of the electromagnetic spectrum to deny its use by an adversary. ... Extremely low frequency (ELF) is the band of radio frequencies from 3 to 30 Hz. ...


Modern anti-submarine warfare

An MH-60R conducts an airborne low frequency sonar (ALFS) operation during testing and evaluation.
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An MH-60R conducts an airborne low frequency sonar (ALFS) operation during testing and evaluation.

In modern times infra-red (FLIR) detectors have been used to track the large plumes of heat that fast nuclear-powered submarines leave to rise to the surface. FLIR devices are also used to see periscopes or snorts at night whenever a submariner might be incautious enough to probe the surface. Image File history File links MH-60R.jpg Summary 030100-N-9999Z-001 Caribbean Sea (Jan. ... Image File history File links MH-60R.jpg Summary 030100-N-9999Z-001 Caribbean Sea (Jan. ... A forward looking infrared (FLIR) system is a camera that takes pictures using the infrared portion of the electromagnetic spectrum. ... Search and attack periscopes of a French-built Scorpène class submarine. ... Snorkel A snorkel (also spelled schnorkel or schnorchel) is a tube that allows a person, vehicle, or vessel to draw air while submerged under water. ...


Today many nations cultivate offshore seabeds of listening devices capable of tracking submarines within the coverage area of the devices. It is known to be possible to detect man-made marine noises as far as right across the southern Indian Ocean from South Africa to New Zealand.


Technologies used

There are a large number of technologies used in modern anti-submarine warfare:

Sound is a disturbance of mechanical energy that propagates through matter as a wave. ... // The F70 type frigates (here, La Motte-Picquet) are fitted with VDS (Variable Depth Sonar) type DUBV43 or DUBV43C tugged sonars SONAR (SOund Navigation And Ranging) â€” or sonar â€” (the British used Anti-Submarine Detection Investigation Committee (ASDIC) until 1948) is a technique that uses sound propagation under water to navigate... Sonarbuoy loaded on aircraft A sonobuoy (a portmanteau of sonar and buoy) is a relatively small (typically 4 7/8 inches, or ~124 mm, in diameter and 36 inches, or ~914 mm, long) expendable sonar system that is dropped/ejected from aircraft or ships conducting anti-submarine warfare or underwater... A hydrophone is a sound-to-electricity transducer for use in water or other liquids, analogous to a microphone for air. ... A mass stranding of Blackfish A beached whale is a whale which has become stranded on land, usually on a beach. ... Pyrotechnics are used in the entertainment industry The band Rammsteins stage acts centers largely around pyrotechnics Pyrotechnics is a field of study often thought synonymous with the manufacture of fireworks, but more accurately has a wider scope that includes items for military and industrial uses. ... It has been suggested that Decompression_buoy, Lifting bag be merged into this article or section. ... This article is concerned solely with chemical explosives. ... Edisons classical searchlight cart. ... This long range RADAR antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll[1]. RADAR is a system that uses radio waves to detect, determine the direction and distance and/or speed... Inspecting an AN/ALQ-184 Electronic Attack Pod Electronic countermeasures (ECM) are any sort of electrical or electronic device designed to spoof radar, sonar, or other detection systems. ... Chaff is a radar countermeasure in which aircraft or other targets spread a cloud of small, thin bits of aluminum or plastic, which either appears as a cluster of secondary targets on radar screens or swamps the screen with multiple returns. ... A magnetic anomaly detector (MAD) is a piece of equipment that is used to detect minute variations in the Earths magnetic field. ... A forward looking infrared (FLIR) system is a camera that takes pictures using the infrared portion of the electromagnetic spectrum. ...

See also

It is tempting to regard modern naval combat as the purest expression of tactics. ... The development of the steam ironclad firing explosive shells in the mid 19th century rendered sailing tactics obsolete. ... A Hedgehog depth charge launcher. ...

References

  • Blair, Clay, Silent Victory (Vol.1), The Naval Institute Press, 2001
  • Lanning, Michael Lee (Lt. Col.), Senseless Secrets: The Failures of U.S. Military Intelligence from George Washington to the Present, Carol Publishing Group, 1995

 
 

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