Peskett had built a large model of the proposed ship in 1902 showing a three-funnel design. A fourth funnel was implemented into the design in 1904 as it was necessary to vent the exhaust from additional boilers fitted after steam turbines had been settled on as the power plant. The original plan called for three propellers, but this was altered to four because it was felt the necessary power could not be transmitted through just three. Four turbines would drive four separate propellers, with additional reversing turbines to drive the two inboard shafts only. To improve efficiency, the two inboard propellers rotated inward, while those outboard rotated outward. The outboard turbines operated at high pressure; the exhaust steam then passing to those inboard at relatively low pressure.