 The submarine was equipped with twin Daimler diesel engines and twin electric motors — for surfaced and submerged running , respectively — that drove one propeller shaft . UB @-@ 42 had a surface speed of up to 9 @.@ 06 knots ( 16 @.@ 78 km / h ; 10 @.@ 43 mph ) and could go as fast as 5 @.@ 71 knots ( 10 @.@ 57 km / h ; 6 @.@ 57 mph ) while underwater . The U @-@ boat could carry up to 28 tonnes ( 28 long tons ) of diesel fuel , giving her a range of 7 @,@ 030 nautical miles ( 13 @,@ 020 km ; 8 @,@ 090 mi ) at 5 knots ( 9 @.@ 3 km / h ; 5 @.@ 8 mph ) . Her electric motors and batteries provided a range of 45 nautical miles ( 83 km ; 52 mi ) at 4 knots ( 7 @.@ 4 km / h ; 4 @.@ 6 mph ) while submerged . 
