 Bonte led a destroyer minelaying sortie to the Newcastle area on the night of 10 / 11 January with Ihn , Heidkamp , Eckoldt , Z22 Anton Schmitt , Richard Beitzen , and Z20 Karl Galster . Ihn had problems with her boilers that reduced her maximum speed to 27 knots ( 50 km / h ; 31 mph ) and she had to be escorted back to Germany by Beitzen . This minefield only claimed one fishing trawler of 251 tons . Max Schultz , Richard Beitzen and Z16 Friedrich Eckoldt laid 110 magnetic mines in the Shipwash area , off Harwich , on 9 / 10 February 1940 that sank six ships of 28 @,@ 496 GRT and damaged another . 
