Dreadnought's machinery combined speed with redundancy

Eighteen Babcock and Wilcox boilers supplied two turbine sets producing 23,000 shaft horsepower and a top speed of 21 knots. The power was distributed across four shafts even though other navies could save weight and expense with three. Britain accepted that penalty to preserve propulsion if a shaft or an engine was damaged. The machinery arrangement therefore joined high speed to redundancy rather than pursuing speed as an isolated performance figure. Both qualities served a navy that expected its battleships to maneuver tactically and operate across large sea areas.