During their 1930s modernization , the boilers on each ship were replaced by eight new Kampon oil @-@ fired boilers , fitted into the former aft boiler room , and the forward funnel was removed . The turbines were replaced by four geared Kampon turbines with a designed output of 80 @,@ 000 shp ( 60 @,@ 000 kW ) intended to increase their speed to 24 @.@ 5 knots ( 45 @.@ 4 km / h ; 28 @.@ 2 mph ) . On her trials , Ise reached a top speed of 25 @.@ 26 knots ( 46 @.@ 78 km / h ; 29 @.@ 07 mph ) from 81 @,@ 050 shp ( 60 @,@ 440 kW ) . The fuel storage of the ships was increased to a total of 5 @,@ 113 long tons ( 5 @,@ 195 t ) of fuel oil that gave them a range of 7 @,@ 870 nautical miles ( 14 @,@ 580 km ; 9 @,@ 060 mi ) at a speed of 16 knots ( 30 km / h ; 18 mph ) .