Parsons maintained that he could design engines capable of maintaining a speed of , which would require . The largest turbine sets built thus far had been of for the -class battleships, and for -class battlecruisers, which meant the engines would be of a new, untested design. Turbines offered the advantages of generating less vibration than the reciprocating engines and greater reliability in operation at high speeds, combined with lower fuel consumption. It was agreed that a trial would be made by fitting turbines to , which was already under construction. The result was a ship faster than her conventionally powered sister with the expected improvements in passenger comfort and operating economy.