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Mark XVlll (Mark 8) buoyant mine with Mark XVlll (Mark 8) sinker

Date1950s

Object number00000420

NameNaval mine

MediumMetal, glass, lead

DimensionsOverall: 1780 mm, 1190 kg, 1145 mm

ClassificationsArmament

Credit LineANMM Collection Transferred from the Department of Defence (Navy)

Terms

DescriptionThe Mark XVIII naval contact mine was designed during WWII and tens of thousands were deployed in oceans, harbours and seas around the world. The horns, when broken, released an acid which detonated the mine. The yellow band indicates an active mine.HistoryMines such as this were designed mainly for two purposes - to make the enemy avoid an area or to sink and damage enemy shipping. It is a self-contained explosive device deployed in the water. They are left in strategic locations, waiting until the target comes to them, when they are triggered by the approach of or contact with an enemy craft. Offensive mines are placed in enemy waters - outside harbours and along important shipping routes - and defensive mines are used to protect harbours, ports and important coastlines. This naval mine is attached to a sinker - the box on which it sits. When deployed from a mine laying vessel, the mine and its sinker fall to the bottom of the sea whereupon the mine, connected to the sinker by a tether, is released to float to or near the surface. The sinker then acts as an anchor, retaining the mine in the desired location. The flanged wheels on the sinker permit it to run down the launching rails of the vessel. The Hertz horn was developed in 1868 by the Prussian scientist Dr Albert Hertz. As a ship's hull comes into contact with the horn and crushes it, the glass phial inside cracks allowing the acid to run down a tube and into a lead-acid battery which then becomes energised and detonates the explosive. The Mark XVIII was designed as the standard British contact mine of World War II.SignificanceThis is a typical example of a naval mine of World War II and represents an efficient weapon in sea warfare.