Limbo, or Anti Submarine Mortar Mark 10 (A/S Mk.10), was the final development of the forward-throwing

anti-submarine An anti-submarine weapon (ASW) is any one of a number of devices that are intended to act against a submarine and its crew, to destroy (sink) the vessel or reduce its capability as a weapon of war. In its simplest sense, an anti-submarine weapon ...

weapon

Squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

, designed during the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

and was developed by the

Admiralty Underwater Weapons Establishment The Admiralty Underwater Weapons Establishment was an Admiralty research department dedicated to underwater detection systems and weapons. It was formed at the Isle of Portland in 1959 and later became part of the Admiralty Research Establishmen ...

in the 1950s. Limbo was installed on the

quarterdeck The quarterdeck is a raised deck behind the main mast of a sailing ship. Traditionally it was where the captain commanded his vessel and where the ship's colours were kept. This led to its use as the main ceremonial and reception area on bo ...

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

escort ships from 1955 to the mid-1980s, Australian-built

destroyer In naval terminology, a destroyer is a fast, maneuverable, long-endurance warship intended to escort larger vessels in a fleet, convoy, or carrier battle group and defend them against a wide range of general threats. They were conceived i ...

and s. Limbo was widely employed by the

Royal Canadian Navy The Royal Canadian Navy (RCN; , ''MRC'') is the Navy, naval force of Canada. The navy is one of three environmental commands within the Canadian Armed Forces. As of February 2024, the RCN operates 12 s, 12 s, 4 s, 4 s, 8 s, and several auxiliary ...

, being incorporated into all destroyer designs from the late 1950s to the early 1970s, including the , , , and classes and the Type 12 President Class frigates built for the South African Navy in the 1960s.

Operation

Limbo was loaded and fired automatically with the crew under cover and was stabilised in pitch and roll. The firing distance of the mortars was controlled by opening gas vents; rounds could be fired from . The weapon was linked to the

sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances ( ranging), communicate with or detect objects o ...

system of the ship, firing on command when the target was in range. The rounds were projected so that they fell in a triangular pattern around the target in any direction around the ship. The weapon was used in the 1982

Falklands War The Falklands War () was a ten-week undeclared war between Argentina and the United Kingdom in 1982 over two British Overseas Territories, British dependent territories in the South Atlantic: the Falkland Islands and Falkland Islands Dependenci ...

and remained in service in the Royal Navy and Commonwealth navies until the 1990s.

Sonar control of the A/S Mortar Mk 10

The firing of the Mortar Mk 10 was controlled by the Type 170 (and later the 502) attack sonar from the Sonar Control Room (SCR), which was generally located next to the operations room in the warship. The 170 sonar had three operators who maintained sonar contact with the target and aimed the weapon in bearing, range and depth. Firing was done by means of a pistol grip and trigger mounted to the deckhead.

Surviving examples

* Explosion Museum of Naval Firepower, Gosport, Hampshire. *

Dutch Navy Museum The Dutch Navy Museum is a naval museum in Den Helder, Netherlands. The museum is dedicated to the history of the ''Koninklijke Marine'' (Royal Netherlands Navy). The most important ships the museum owns are: * (minesweeper) * ( ironclad ram) * ...

, Den Helder, Netherlands. * The Naval Museum of Alberta, Calgary, Alberta.

General characteristics

* Total system weight: 35 tons including 51 projectiles (17 salvos).

References

{{Reflist 305 mm artillery Anti-submarine mortars Explosive weapons Military equipment introduced in the 1950s Naval weapons of the Cold War Naval weapons of the United Kingdom