High Quality Content by WIKIPEDIA articles! The R boats or Räumboote in German were a group of small Minesweepers but used in General purpose. A total of 424 boats were built for the Kriegsmarine before and during World War II. The German Navy used them in every theatre including the Baltic, Mediterranean and the Black Sea. These boats were used for convoy escort, coastal patrol, minesweeping, minelaying and air-sea rescue. About 140 R boats survived the war and were distributed amongst the Allies. Some were used by the "German Minesweeping service" to clear western Europe of sea mines. Twenty four boats ended up being transferred back to the post-war German Navy, the Bundesmarine in 1956 and were used until the late 1960s. An unusual feature of these ships is the use of Voith Schneider Propellers on approximately one quarter of the boats for extra maneuverability.