INFO ONLY. GALLERY PICTURE. NOT FOR SALE P87-10
German Naval Mine Horn
Floating contact mines
The original mine type floats anywhere from just below the surface of the water to several hundred meters down. A cable connecting the mine to an anchor on the seabed prevents them from drifting away. The explosive and detonating mechanism is contained in a metal or plastic shell, which also has considerable buoyancy. The depth below the surface at which the mine floats can be set so that only deep draft vessels such as aircraft carriers, battleships or large cargo ships are at risk. This avoids a "less valuable" ship detonating the mine.
Early mines had mechanical mechanisms to detonate them, but these were superseded in the 1870s by the Hertz Horn (or chemical horn), which was found to work reliably even after the mine had been in the sea for several years. The mine's upper half is studded with hollow lead protuberances, each containing a glass vial filled with sulfuric acid. When a ship's hull crushes the metal horn, it cracks the vial inside it, allowing the acid to run down a tube and into a lead-acid battery which until then contains no acid electrolyte. This energizes the battery, which detonates the explosive.
Earlier forms of the detonator used a vial filled with sulfuric acid, surrounded by the mixture of potassium perchlorate and sugar. When the vial was crushed, the acid ignited the perchlorate-sugar mix, and the resulting flame ignited the gunpowder charge.
