 The ships ' propulsion system consisted of one single @-@ expansion steam engine that drove a single screw propeller , with steam supplied by six coal @-@ fired , cylindrical fire @-@ tube boilers . The boilers were <unk> into a single funnel . The lead ship 's engine produced a top speed of 12 @.@ 2 knots ( 22 @.@ 6 km / h ; 14 @.@ 0 mph ) at 6 @,@ 117 indicated horsepower ( 4 @,@ <unk> kW ) , while Palestro made 12 @.@ 85 kn ( 23 @.@ 80 km / h ; 14 @.@ 79 mph ) at the same horsepower . They could steam for 1 @,@ 780 nautical miles ( 3 @,@ 300 km ; 2 @,@ 050 mi ) at a speed of 10 knots ( 19 km / h ; 12 mph ) . The ships were barque @-@ rigged to supplement the steam engine ; Principe Amedeo and her sister were the last rigged ironclad to be built by Italy . The ships ' sail area were 36 @,@ 738 square feet ( 3 @,@ <unk> @.@ 1 m2 ) for Principe Amedeo and 37 @,@ 361 sq ft ( 3 @,@ <unk> @.@ 0 m2 ) for Palestro . 
