Anti-submarine mortar
Encyclopedia
Anti-submarine mortars are artillery pieces deployed on ships for the purpose of sinking submarine
s by a direct hit with a small explosive charge. They are often larger versions of the mortar
used by infantry
and fire a projectile in relatively the same manner. They were created during World War II
as a development of the depth charge
and work on the same principle.
Anti-submarine warfare did not become an issue of great concern until World War I
, when Germany used submarines in an attempt to strangle British shipping in the Atlantic Ocean
and elsewhere. The earliest way to counter a submarine was in the form of depth charge
s, which were large canisters filled with explosives, rolled off the back of a ship and detonated by a hydrostatic fuse. Depth charges served well throughout World War I but were not without flaws. A ship had to pass directly over a submarine to score an effective hit, because of this depth charges were dropped in lines instead of more effective clusters and could only be carried in ships fast enough to avoid the concussion of the explosion. The depth charges were also not as effective as one might think at sinking a submarine - only a very close detonation would sink a submarine, and the problems of scoring a direct hit meant that a submarine was more often damaged then destroyed by depth charges.
After WWI depth charge throwers were developed, which could hurl depth charges some 100 feet (30.5 m) off the side of a ship. These were a significant improvement over the old method, permitting the use of large 'patterns' of up to 10 depth charges from the throwers and stern depth charge rails used together. However they still required a ship to pass very close to a submarine, which entailed loss of sonar (ASDIC) contact during the final stages of the approach. Submarines could and did use this dead interval to take evasive action.
During WW2 more effective systems, and the first Anti-submarine mortars, were developed. These all had the common characteristic of throwing the charge(s) ahead of the attacking vessel, while it was still in sonar contact. The first was the famous "Hedgehog"
, which consisted of 24 small mortar rounds, each one 7 inches (177.8 mm) in diameter and weighing 65 pounds with a 35-pound warhead. Each projectile had a range of about 250 yards (228.6 m) and was fired in a circular pattern in front of a ship. While the warhead on a Hedgehog was much smaller than that of a depth charge it scored three times as many kills then its predecessors. This was due to the use of a contact fuse
on the projectile, which would only detonate on impact with a target. Since the projectile would only explode on a hit the long periods of sonar
"blackout" from the blast and turbulence of a conventional depthcharge explosion were eliminated. The Hedgehog was followed by the Squid three-barreled depth charge mortar, the two weapons remaining in service alongside each other in the later stages of WW2. Squid fired 390-lb depth charges to a range of 250 metres.
The homing torpedo
has largely replaced the anti-submarine mortar in naval combat, although several examples still exist. The British Limbo
system, with three gyro-stabilized barrels, fires 350-pound projectiles to a range of 1000 yards (914.4 m). It remained in service with many British
and Commonwealth navies until the 1980s. The Bofors
anti-submarine mortar, which uses a rocket motor in place of an explosive charge, is still in use with the Swedish Navy
. Due to the poor sonar conditions of the Baltic Sea
the mortar still retains a place next to torpedoes. It has two or four barrels and fires a 550-pound projectile up to 3800 yards (3,474.7 m). The former Soviet Navy
(and by extension, the Russian Navy) is the largest user of anti-submarine mortars. Keeping with the Soviet idea that weapons should be simple and cheap, several versions of rocket-propelled anti-submarine mortars were developed. There were also conducted trials of destroying oncoming torpedoes with anti-submarine mortars. The most common is the RBU-6000
, which fires twelve 160-pound projectiles in a horseshoe pattern up to 6500 yards (5,943.6 m) away. There was also a more extreme version, the nuclear SUW-N-1, though this is more technically an anti-submarine rocket. It had anti-surface and land-attack uses as well.
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
s by a direct hit with a small explosive charge. They are often larger versions of the mortar
Mortar (weapon)
A mortar is an indirect fire weapon that fires explosive projectiles known as bombs at low velocities, short ranges, and high-arcing ballistic trajectories. It is typically muzzle-loading and has a barrel length less than 15 times its caliber....
used by infantry
Infantry
Infantrymen are soldiers who are specifically trained for the role of fighting on foot to engage the enemy face to face and have historically borne the brunt of the casualties of combat in wars. As the oldest branch of combat arms, they are the backbone of armies...
and fire a projectile in relatively the same manner. They were created during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
as a development of the depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...
and work on the same principle.
Beginnings
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
, when Germany used submarines in an attempt to strangle British shipping in the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
and elsewhere. The earliest way to counter a submarine was in the form of depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...
s, which were large canisters filled with explosives, rolled off the back of a ship and detonated by a hydrostatic fuse. Depth charges served well throughout World War I but were not without flaws. A ship had to pass directly over a submarine to score an effective hit, because of this depth charges were dropped in lines instead of more effective clusters and could only be carried in ships fast enough to avoid the concussion of the explosion. The depth charges were also not as effective as one might think at sinking a submarine - only a very close detonation would sink a submarine, and the problems of scoring a direct hit meant that a submarine was more often damaged then destroyed by depth charges.
Early anti-submarine mortars
During WW2 more effective systems, and the first Anti-submarine mortars, were developed. These all had the common characteristic of throwing the charge(s) ahead of the attacking vessel, while it was still in sonar contact. The first was the famous "Hedgehog"
Hedgehog (weapon)
The Hedgehog was an anti-submarine weapon developed by the Royal Navy during World War II, that was deployed on convoy escort warships such as destroyers to supplement the depth charge. The weapon worked by firing a number of small spigot mortar bombs from spiked fittings...
, which consisted of 24 small mortar rounds, each one 7 inches (177.8 mm) in diameter and weighing 65 pounds with a 35-pound warhead. Each projectile had a range of about 250 yards (228.6 m) and was fired in a circular pattern in front of a ship. While the warhead on a Hedgehog was much smaller than that of a depth charge it scored three times as many kills then its predecessors. This was due to the use of a contact fuse
Contact fuse
A contact fuze, percussion fuze or direct-action fuze is the fuze that is placed in the nose of a bomb or shell so that it will detonate on contact with a hard surface....
on the projectile, which would only detonate on impact with a target. Since the projectile would only explode on a hit the long periods of sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...
"blackout" from the blast and turbulence of a conventional depthcharge explosion were eliminated. The Hedgehog was followed by the Squid three-barreled depth charge mortar, the two weapons remaining in service alongside each other in the later stages of WW2. Squid fired 390-lb depth charges to a range of 250 metres.
Modern uses
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...
has largely replaced the anti-submarine mortar in naval combat, although several examples still exist. The British Limbo
Limbo (weapon)
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 Squid that it superseded, was developed by the Admiralty Underwater Weapons...
system, with three gyro-stabilized barrels, fires 350-pound projectiles to a range of 1000 yards (914.4 m). It remained in service with many British
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
and Commonwealth navies until the 1980s. The Bofors
Bofors
The name Bofors has been associated with the iron industry for more than 350 years.Located in Karlskoga, Sweden, the company originates from the hammer mill "Boofors" founded 1646. The modern corporate structure was created in 1873 with the foundation of Aktiebolaget Bofors-Gullspång...
anti-submarine mortar, which uses a rocket motor in place of an explosive charge, is still in use with the Swedish Navy
Swedish Navy
The Royal Swedish Navy is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet – as well as marine units, the so-called Amphibious Corps .In Swedish, vessels of the Swedish Navy are given the prefix "HMS," short for Hans/Hennes...
. Due to the poor sonar conditions of the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
the mortar still retains a place next to torpedoes. It has two or four barrels and fires a 550-pound projectile up to 3800 yards (3,474.7 m). The former Soviet Navy
Soviet Navy
The Soviet Navy was the naval arm of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy would have played an instrumental role in a Warsaw Pact war with NATO, where it would have attempted to prevent naval convoys from bringing reinforcements across the Atlantic Ocean...
(and by extension, the Russian Navy) is the largest user of anti-submarine mortars. Keeping with the Soviet idea that weapons should be simple and cheap, several versions of rocket-propelled anti-submarine mortars were developed. There were also conducted trials of destroying oncoming torpedoes with anti-submarine mortars. The most common is the RBU-6000
RBU-6000
The RBU-6000 Smerch-2 is a 213 mm caliber Soviet anti-submarine rocket launcher. It is similar in principle to the Royal Navy Hedgehog system used during the Second World War...
, which fires twelve 160-pound projectiles in a horseshoe pattern up to 6500 yards (5,943.6 m) away. There was also a more extreme version, the nuclear SUW-N-1, though this is more technically an anti-submarine rocket. It had anti-surface and land-attack uses as well.
See also
- Hedgehog (weapon)Hedgehog (weapon)The Hedgehog was an anti-submarine weapon developed by the Royal Navy during World War II, that was deployed on convoy escort warships such as destroyers to supplement the depth charge. The weapon worked by firing a number of small spigot mortar bombs from spiked fittings...
- Squid (weapon)Squid (weapon)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....
- Limbo (weapon)Limbo (weapon)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 Squid that it superseded, was developed by the Admiralty Underwater Weapons...
- Mousetrap (weapon)Mousetrap (weapon)Mousetrap was an anti-submarine rocket used mainly during the Second World War by the U.S. Navy and the U.S. Coast Guard. Its development was begun in 1941 as a replacement for Hedgehog, a British-made projector, which was the first ahead-throwing ASW weapon...