The five boilers (4 boilers after 1883) powered the 2 engines whose power was transfered by 2 shafts to the twin propellers. The Australasian Sketcher, July 11 1874
"The Cerberus is propelled by twin screws, so that she can turn on her own length, and the screws are fitted with Maudslay's Shifting blades."
The rudder & screws were well protected by the overhanging stern.
6 mouseovers (each blade on starboard screw, rudder & port screw.)