 The ship was fitted with a two @-@ cylinder , horizontal direct @-@ acting steam engine built by the Belgian Cockerill Company . It drove a single propeller using steam that was provided by two rectangular boilers . Specific information on the output of the ship 's engine has not survived , but it ranged between 340 – 500 indicated horsepower ( 254 – 373 kW ) for all the ships of this class . During Koldun 's sea trials on 21 July 1864 , she reached a maximum speed of 6 knots ( 11 km / h ; 6 @.@ 9 mph ) . The ship carried a maximum of 190 long tons ( 190 t ) of coal , which gave her a theoretical endurance of 1 @,@ 440 nmi ( 2 @,@ 670 km ; 1 @,@ 660 mi ) at 6 knots ( 11 km / h ; 6 @.@ 9 mph ) . 
