Patrick Harris -
|An Admirable Class Minesweeper (USN)|
Minesweeping serves an important purpose. The job of a minesweeper is to clear sea-lanes of mines (originally referred to as torpedoes). Mines could be of several types. In this article, I will focus on mines used during the Second World War. At this time, the three types of mines used were magnetic, pressure or acoustic. All of these mines relied on proximity to a vessel, as opposed to contact. Magnetic mines were triggered when the steel hull of a ship came within range. Acoustic mines detonated from the vibrations of a nearby ship's propeller, whilst pressure mines reacted to changes in water pressure caused by the passing of a ship. Of these types, magnetic mines could be actively combatted by passing a live wire under the ship (known as degaussing). If this was done properly, the risks of detonating a mine was greatly reduced (Konstam). In order to combat acoustic and pressure mines, minesweepers were put into service.
Minesweepers were usually made of wood (or any kind of non magnetic metal) in order to further counteract the threat of magnetic mines. A Oropesa Sweep (a device which spread wires out behind the minesweeper to "catch" mines) as well as underwater sound projection in front of the minesweeper (to detonate acoustic mines) were two of the most popular methods for dealing with the extensive numbers, and mixed types, of mines which were laid during the Second World War (Konstam).