Propulsion was achieved through three propellers: two outboard or wing propellers had three blades, while the central propeller had four. The two lateral propellers were powered by reciprocating steam triple expansion, while the central shaft was driven by a steam turbine. All power on board was derived from a total of 29 coal-fired steam boilers in six compartments. However, "Olympic"s boilers were adapted for firing by oil at the end of the First World War, which reduced the number of engine crew required from 350 to 60.