Squid (weapon)

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Squid Mortar.jpg
Squid anti-submarine mortar on display at the Devonport Naval Base
TypeAnti-submarine Mortar
Place of originUnited Kingdom
Service history
In service19431977
Used by Royal Navy Swedish Navy
Production history
Designer Directorate of Miscellaneous Weapons Development
Mass10 tons

Shell 440 lb (200 kg)
Calibre 12 in (305 mm)
Effective firing range275 yards (250 m)
Filling Minol
Filling weight207 lb (94 kg)
Time fuse

Squid was a British World War II ship-mounted anti-submarine weapon. It consisted of a three-barrelled mortar which launched depth charges. It replaced the Hedgehog system, and was in turn replaced by the Limbo system.

World War II 1939–1945 global war

World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries. The major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 50 to 85 million fatalities, most of whom were civilians in the Soviet Union and China. It included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, and the only use of nuclear weapons in war.

Ship Large buoyant watercraft

A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying passengers or goods, or in support of specialized missions, such as defense, research and fishing. Historically, a "ship" was a sailing vessel with at least three square-rigged masts and a full bowsprit. Ships are generally distinguished from boats, based on size, shape, load capacity, and tradition.

Anti-submarine warfare Branch of naval warfare

Anti-submarine warfare is a branch of underwater warfare that uses surface warships, aircraft, or other submarines to find, track, and deter, damage, or destroy enemy submarines.


Sailors loading Squid anti-submarine mortar in 1952 Sailors loading Squid anti-submarine mortar in 1952.jpg
Sailors loading Squid anti-submarine mortar in 1952
Squid bomb markings diagram Squid bomb markings diagram.jpg
Squid bomb markings diagram

Literally ordered directly from the drawing board in 1942, under the auspices of the Directorate of Miscellaneous Weapons Development, this weapon was rushed into service in May 1943 on board HMS Ambuscade. The first production unit was installed on HMS Hadleigh Castle; it went on to be installed on 70 frigates and corvettes during the Second World War. The first successful use was by HMS Loch Killin on 31 July 1944, when she sank U333 ; the system was credited with sinking 17 submarines in 50 attacks. By 1959, 195 Squid installations had been produced.

HMS <i>Ambuscade</i> (D38) ship

HMS Ambuscade was a British Royal Navy destroyer which served in the Second World War. She and her Thornycroft competitor, HMS Amazon, were prototypes designed to exploit advances in construction and machinery since World War I and formed the basis of Royal Navy destroyer evolution up to the Tribal of 1936.

HMS <i>Hadleigh Castle</i> (K355)

HMS Hadleigh Castle (K355) was a Castle-class corvette of Britain's Royal Navy.

This weapon was a three-barrel 12-inch (305 mm) mortar with the mortars mounted in series but off-bore from each other in order to scatter the projectiles. The barrels were mounted in a frame that could be rotated through 90 degrees for loading. The projectiles weighed 390 pounds (177 kg) with a 207-pound (94 kg) minol charge. [Note 1] On some vessels, the Squid installations were at the stern – the bombs were fired over the length of the ship and dropping into the sea slightly ahead of it. [1] Sink rate was 43.5 ft/s (13.3 m/s) and a clockwork time fuze was used to determine the detonation depth; all three projectiles had to be set to the same depth; this could be continuously updated right up to the moment of launch to take into account the movements of the target. [1] The maximum depth was 900 feet (270 m).

Minol is a military explosive developed by the British Admiralty early in the Second World War to augment supplies of trinitrotoluene (TNT) and RDX, which were then in short supply. The aluminium component in Minol significantly prolongs the explosive pulse, making it ideal for use in underwater naval weapons where munitions with a longer explosive pulse are more destructive than those with high brisance.

Fuse (explosives) part of a device that initiates function in an explosive, pyrotechnic device or military munition

In an explosive, pyrotechnic device, or military munition, a fuse is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately. However, when being specific, the term fuse describes a simple pyrotechnic initiating device, like the cord on a firecracker whereas the term fuze is sometimes used when referring to a more sophisticated ignition device incorporating mechanical and/or electronic components, such as a proximity fuze for an M107 artillery shell, magnetic or acoustic fuze on a sea mine, spring-loaded grenade fuze, pencil detonator, or anti-handling device.

The weapons were automatically fired from the sonar range recorder at the proper moment. The pattern formed a triangle about 40 yards (37 m) on a side at a distance of 275 yards (250 m) ahead of the ship. Most Squid installations utilised two sets of mortars. All six bombs were fired in salvo so they formed opposing triangular spreads. The salvos were set to explode 25 feet (10 m) above and below the target, the resulting pressure wave crushing the hull of the submarine. Postwar trials found Squid was nine times more effective than conventional depth charges. [2]

Sonar technique that uses sound propagation

Sonar is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels. Two types of technology share the name "sonar": passive sonar is essentially listening for the sound made by vessels; active sonar is emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used in air for robot navigation, and SODAR is used for atmospheric investigations. The term sonar is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extremely high (ultrasonic). The study of underwater sound is known as underwater acoustics or hydroacoustics.

Despite its proven effectiveness, some officers, notably Captain Kenneth Adams, RCN, opposed fitting Squid to escorts because it meant sacrificing guns, which would make ships unsuitable for fleet actions. [3]

Captain (naval) Naval military rank

Captain is the name most often given in English-speaking navies to the rank corresponding to command of the largest ships. The rank is equal to the army rank of colonel.

Royal Canadian Navy maritime warfare branch of Canadas military

The Royal Canadian Navy is the naval force of Canada. The RCN is one of three environmental commands within the unified Canadian Armed Forces. As of 2017, Canada's navy operates 12 frigates, 4 patrol submarines, 12 coastal defence vessels and 8 unarmed patrol/training vessels, as well as several auxiliary vessels. The Royal Canadian Navy consists of 8,500 Regular Force and 5,100 Primary Reserve sailors, supported by 5,300 civilians. Vice-Admiral Ron Lloyd is the current Commander of the Royal Canadian Navy and Chief of the Naval Staff.

In April 1977, the Type 61 frigate Salisbury became the last ship to fire Squid in Royal Navy service. Examples of the mortars are on display at the Explosion! Museum of Naval Firepower in Gosport, Hampshire and another at Devonport Naval Base. In addition, the system is fitted to HMS Cavalier (D73), which is part of the historic ships collection in the Historic Dockyard in Chatham, Kent.

HMS <i>Salisbury</i> (F32)

HMS Salisbury was a Salisbury-class or Type 61 aircraft direction frigate of the British Royal Navy. Completed in the late 1950s, Salisbury served through the 1960s and 1970s, participating in the Beira Patrol, blockading against Rhodesia and the confrontation with Iceland over fishing rights that was known as the Cod Wars. Salisbury became a harbour training ship in 1980, before being sunk as a target in 1985.

Explosion! Museum of Naval Firepower Museum in Hampshire, England

Explosion! is the Museum of Naval Firepower situated in the former Royal Naval Armaments Depot at Priddy's Hard, in Gosport, Hampshire, England. It now forms part of the National Museum of the Royal Navy.

In Swedish service the system soldiered on until 1982 when the Östergötland-class destroyers were decommissioned.


  1. Due to shortages of TNT and RDX (cyclonite) in World War II, the British used a 50/50 mixture of ammonium nitrate and TNT (amatol) in naval mines and depth charges. This low grade explosive was later improved by the addition of about 20% aluminium powder, producing minol .

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Naval artillery artillery mounted on a warship

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Limbo, or Anti Submarine Mortar Mark 10, was the final British development of a forward-throwing anti-submarine weapon originally designed during the Second World War. Limbo, a three-barreled mortar similar to the earlier Hedgehog and Squid which it superseded, was developed by the Admiralty Underwater Weapons Establishment in the 1950s. Squid was loaded manually, which was difficult on a pitching deck in heavy seas with no protection from the elements; in contrast Limbo was loaded and fired automatically, with all the crew under cover. It was widely fitted on the quarterdeck of Royal Navy escort ships on a mounting stabilised for pitch and roll from 1955 to the mid-1980s. Australian built versions of the Daring-class destroyer all carried Limbo as did the Australian River-class destroyer escort. Limbo was also widely employed by the Royal Canadian Navy, being incorporated into all destroyer designs from the late 1950s to the early 1970s, including the St. Laurent, Restigouche, Mackenzie, Annapolis and Iroquois classes.

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HMS <i>Woolvesey Castle</i> (K461)

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  1. 1 2 "Squid Mortar". Friends of HMCS Haida. Archived from the original on 17 February 2012. Retrieved 21 March 2012.
  2. Zimmerman, David. Great Naval Battle of Ottawa (Toronto: University of Toronto Press, 1989), p. 127.
  3. Zimmerman, pp. 128–129.