The class used 18 boilers, two turbine sets and four shafts to produce 27,000 shaft horsepower and a top speed of 21 knots. Its quoted range was 6,730 nautical miles at 10 knots, so endurance belonged beside speed in the design calculation. These figures follow an on-air correction from HMS Dreadnought's lower power and range values. They also illustrate the case for incremental design. A limited leap could still leave a serviceable vessel if it fell short, while a radical gamble risked an expensive failure with strategic and political consequences.
Chapter · 27:35-29:22
Propulsion figures and controlled innovation
Orion retained a 21-knot top speed despite more power, reflecting a preference for improvements that would still leave Britain with a useful ship if an ambitious change disappointed.