 The drivetrain of the boats consisted of a single propeller shaft driven by a Daimler ( Germaniawerft ) or Körting ( Weser ) diesel engine on the surface , or a Siemens @-@ Schuckert electric motor for underwater travel . The Weser boats were capable of nearly 7 @.@ 5 knots ( 13 @.@ 9 km / h ; 8 @.@ 6 mph ) on the surface and a little more than 6 knots ( 11 km / h ; 6 @.@ 9 mph ) submerged . The Germaniawerft boats were about 1 knot ( 1 @.@ 9 km / h ; 1 @.@ 2 mph ) slower than their Bremen @-@ made counterparts . The boats were equipped with two 45 @-@ centimetre ( 17 @.@ 7 in ) bow torpedo tubes and carried two torpedoes . They were also armed with a single 8 @-@ millimetre ( 0 @.@ 31 in ) machine gun affixed to the deck . 
