Magnetic pistol is the term for the device on a
torpedo
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, s ...
or
naval mine
A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any ...
that detects its target by its magnetic field, and triggers the fuse for detonation. A device to detonate a torpedo or mine on ''contact'' with a ship or submarine is known as a
contact pistol
A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any ve ...
.
A magnetic pistol on a mine will allow the mine to detonate in proximity to a target, rather than actual contact, allowing the mine to cover a larger effective area.
A magnetic pistol on a torpedo allows the torpedo to detonate underneath the ship, instead of upon impact with the side of the ship. As an explosion underneath a ship is contained between water and the ship, far more damage will result to the ship. The explosion will lift the ship out of the water and may break the keel of the ship, splitting it in two. Any hole created by the explosion will be on the bottom, causing more flooding.
A contact pistol on a torpedo will require the torpedo to strike the side of the ship. Any hole created by the explosion will be closer towards the waterline, reducing flooding. The explosion will also dissipate into the air, reducing the damage. If the torpedo is fired too deep, the torpedo will not hit the ship. If the ship has a round or sloping bottom, the torpedo may glance off the bottom and not detonate.
History
In
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
, German U-boats were using magnetic pistols by 1917, but it would not be until 1918 that Britain would find examples of these while salvaging U-boat
SM ''UB-110''. They proved problematic, often firing prematurely.
During
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
, magnetic pistols often exploded prematurely or not at all. The reason was that magnetic lines are more horizontal close to the equator than towards the poles. For example, the US
Mark 6 magnetic pistol was designed and tested only once at 41° latitude (60°
geomagnetic latitude Geomagnetic latitude, or magnetic latitude (MLAT), is a parameter analogous to geographic latitude, except that, instead of being defined relative to the geographic poles, it is defined by the axis of the geomagnetic dipole, which can be accurately ...
) at
Narragansett Bay
Narragansett Bay is a bay and estuary on the north side of Rhode Island Sound covering , of which is in Rhode Island. The bay forms New England's largest estuary, which functions as an expansive natural harbor and includes a small archipelago. Sm ...
, but was primarily used in equatorial latitudes.
[Friedman. ''U.S. Submarines Through 1945'' p. 242.] At the equator, the signal strength to the Mark 6 magnetic pistol was only about half that of where the Mark 6 was tested. Moreover, relative velocity (i.e. when a torpedo is fired from behind or in front of a ship) would additionally change the abruptness of the magnetic signal, resulting in the magnetic pistol being triggered prematurely or not at all.
Eventually, the US Mark 6 magnetic pistol was replaced by contact pistols (which, in the cases of the US
Mark 14
Mark 14 is the fourteenth chapter of the Gospel of Mark in the New Testament of the Christian Bible. It contains the plot to kill Jesus, his anointing by a woman, the Last Supper, predictions of his betrayal, and Peter the Apostle's three deni ...
submarine torpedo and
Mark 15 ship torpedo, proved to be unreliable as well).
Some ships carry
degaussing
Degaussing is the process of decreasing or eliminating a remnant magnetic field. It is named after the gauss, a unit of magnetism, which in turn was named after Carl Friedrich Gauss. Due to magnetic hysteresis, it is generally not possible to red ...
equipment to reduce the signal detected by a magnetic pistol.
See also
*
Influence mines
References
External links
German U-Boat Torpedo SpecificationsU.S. Submarines Through 1945
{{DEFAULTSORT:Magnetic Pistol
Naval weapons