Limpet mine
It is so named because of its superficial similarity to the shape of the limpet, a type of sea snail that clings tightly to rocks or other hard surfaces.
Sometimes limpet mines have been fitted with a small turbine which would detonate the mine after the ship had sailed a certain distance, so that it was likely to sink in navigable channels (to make access difficult for other ships) or deep water (out of reach of easy salvage) and making determination of the cause of the sinking more difficult.
[6][7] Macrae and Clarke soon agreed to cooperate on the design of a new weapon, but they quickly abandoned a towed mine as impractical.
[9] The body of the prototype was a large metal kitchen bowl obtained from the Bedford branch of Woolworths and modified by a local tinsmith to retain the magnets around the rim.
After much experimentation, it was found that the detonator could be actuated by a slowly dissolving aniseed ball sweet to provide the necessary time to escape.
The prototype was tested in the swimming pool at Bedford Modern School, using a steel plate lowered into the deep end to simulate a ship's hull.
He served in the Special Operations Executive (SOE) with Colin Gubbins and was later Commandant of one of the Secret Intelligence Service's schools.
The "rigid limpets" used by the British during World War II contained only 4+1⁄2 pounds (2.0 kg) of explosive,[14] but placed two metres (6.6 ft) below the waterline they made a wide hole in an unarmoured ship.
In the end, the Soviets didn't care for the idea of the magnetic mine, and the Germans stopped using Zimmerit for the last year of the war.
[18] An example of the use of limpet mines by British special forces was in Operation Frankton which had the objective of disabling and sinking merchant shipping moored at Bordeaux, France in 1942.
On 16 January 1945, 10 limpet mines were placed along the port side of the SS Donau approximately 50 centimetres (20 in) beneath the waterline.
[21] In 1980, a limpet mine was used to sink Sierra, a whaling vessel docked in Portugal after a confrontation with the Sea Shepherd Conservation Society.
[24][25] On 12 May 2019, four oil tankers in the Emirati port of Fujairah suffered damage from what appeared to be limpet mines or a similar explosive device.
Preliminary findings of the investigation by the UAE, Norway, and Saudi Arabia concluded in June 2019, show that limpet mines were placed on oil tankers to explode as part of a sabotage operation.
[26] On 13 June two subsequent blasts in the Straits of Hormuz damaged a Japanese and a Norwegian tanker, and were blamed on Iran by the U.S. military.
