UJ-121 Jochen was a steam trawler that was built in Germany in 1939, and converted into a submarine chaser at the beginning of the Second World War.

In 1938–39 Norderwerft Köser & Meyer in Steinwerder, Hamburg built a pair of trawlers for the fishing fleet of C Andersen.

[3] Deutsche Schiff- und Maschinenbau (DeSchiMAG) built her engines in its Seebeck works at Wesermünde in Bremerhaven.

It was supplemented by an exhaust steam turbine, which drove the same propeller shaft via DeSchiMAG's patent Bauer-Wach system of a Föttinger fluid coupling and double-reduction gearing.

The combined power of her reciprocating engine plus exhaust turbine was rated at 132 NHP,[3] and gave her a speed of 12 knots (22 km/h).