page_title: Destroyer minesweeper
section_title: Minesweeping methods
hierarchical_section_title: Destroyer minesweeper / Minesweeping methods
caption_attribution_description: English: AWM Caption&#160;: "Australia: New South Wales, Sydney. HMAS SYDNEY. PARAVANE BEING LOWERED INTO SEA.
context_page_description: "Destroyer minesweeper" was a designation given by the United States Navy to a series of destroyers that were converted into high-speed ocean-going minesweepers for service during World War II. The hull classification symbol for this type of ship was "DMS." Forty-two ships were so converted, beginning with USS Dorsey, converted to DMS-1 in late 1940, and ending with USS Earle, converted to DMS-42 in mid 1945. The type is now obsolete, its function having been taken over by purpose-built ships, designated as "minesweeper" with the hull classification symbol MMD.
  The original Clemson class and Wickes class ships were obsolete four-stack destroyers built in 1918 with usable power plants; they were nicknamed "four-pipers" on account of their four smokestacks. Although the full conversion process to minesweepers for the original 17 Wickes and Clemson class destroyers began in October-November of 1940, it was not completed for all seventeen until around mid-1942.
context_section_description: WWII Japan never developed its own magnetic or pressure mines, so for those destroyer minesweepers in the Pacific, mines were usually cut from their mooring by a paravane, shown at left, extended by a sweep line from the rear or sides of a minesweeper, assisted by the use of sonar to locate the submerged mines. Paravanes could be towed from one or both sides of a ship's stern, or occasionally bow, though Destroyer/Minesweepers usually towed them from the stern or on rare occasions amidships.  The sweep line caught the moored mine's cable below the surface, causing the paravane to slide to the mine and have its blades cut the mine from its mooring cable.  The mine then floated to the top and was usually destroyed or sometimes sunk to the bottom by gunfire from an American naval ship.  In some applications, cutting devices were placed on the sweep line itself, or the sweep line could be serrated to do the cutting, but Paravanes with blades were used much more frequently by American ships to cut mooring cables in the Pacific in WWII.  In most configurations, a kite, basically an unbladed paravane, could be used near the ship to maintain the sweep wire parallel to the bottom at a specified distance from the paravane.  The paravane operator would need to know the depth of the moored mines to set the proper depth of the paravane and kite, and could use sonar for this purpose.
  In WWI, the United States, and occasionally the Japanese would deploy anti-sweeping mines designed to cut sweep wires to make the sweeping process more difficult.
  Minesweeping ships would often travel side by side in formation to sweep a larger channel. Large winches and two large davits which looked like cranes on each side of the stern of minesweepers were used to haul minesweeping gear.  Acoustic mines were destroyed by sound generators that imitated the sound frequencies of a passing ship, and electrical mines, though rarely used by the Japanese, could be destroyed by an electrical device or cable passed close to the mine causing it to detonate.  Ship sonar was used as an invaluable tool in locating mines in WWII.  More sophisticated pressure mines were used by Germany in the Atlantic but were not frequent and their use was delayed by the Germans until 1945 at the Battle of Normandy.  Pressure mines were activated by the increase in water pressure under a moving vessel, and had to be swept using a towed hulk large enough to produce the required pressure surge.  Markers in the form of buoys were often used to mark mineswept lanes where transport ships or landing craft could find safe passage to beach heads or other destinations.  Buoys were usually used to mark the end of a mine sweep cable floated directly above the paravane, and could be particularly helpful when minesweepers were sweeping in formation.
caption: WWII paravane
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