The R boats were a group of small naval vessels built as minesweepers for the Kriegsmarine before and during the Second World War. They were used for several purposes during the war, and were also used post-war by the German Mine Sweeping Administration for clearing naval mines.
Aldebaran class R boat
R boats operating near the coast of occupied France
R boats inline, 1939
Steam R boats at work, 1938
Voith Schneider Propeller
The Voith Schneider Propeller (VSP) is a specialized marine propulsion system (MPS) manufactured by the Voith Group based on a cyclorotor design. It is highly maneuverable, being able to change the direction of its thrust almost instantaneously. It is widely used on tugs and ferries.
Voith Schneider Propeller
Lift forces imparted to the VSP from the water body
Path of a blade in the water
Twin Voith Schneider propeller with thrust plate on a tug's hull