They were small minesweepers designed to operate in coastal waters and shallow areas. The Germans built aprox. 300 of them from 1933 till the end of the war. Most of them did not have standard propellors and rudders but horizontally mounted Voith-Schneider propellors which made the boats very maneuverable.
They did mine sweeping, convoy escort, and escorting U-Boots out of there pens.
After the war many were taken over by the Allies: USA got 48, the Soviet Union 45, Denmark 24, Britain 11, the Netherlands 8 and Norway got 4 of them.
Some were eventually used to start the German Minesweeping Service "Deutscher Mienenräumdienst" to remove the minefields in european waters after the war, and 24 were returned to the New German Navy in 1955 and used into the 1960s.
Dimensions
Size (Max): 155 t
Length (Total): 41,0 m
Beam: 5,8 m
Draft: 1,7 m
Weapons
3,7 cm Flak: 1
2 cm MG: 3
8,6 cm Missle Launcher "Föhn": 1
Engines
Voith-Schneider Propellers: 2
Engines: 2
Type: MAN 8-cylinder diesel
Performance
Total Performance: 1800 shp
Speed: 19 kn