How turbine cruising performance expanded fleet mobility

Earlier expansion-engine battleships could reach about 18 knots, while an economical speed might be nearer 15 or 16 knots, with considerable variation between generations. Dreadnoughts made 21 knots appear a substantial improvement, but turbine efficiency, gearing, and boilers continued to develop. A more capable installation could offer a useful operating speed between its most economical setting and maximum power. That intermediate speed could improve strategic movement with a relatively small reduction in range. The benefit depended on having enough speed available above economical cruising speed. A fleet tied to 21-knot capital ships had less freedom to exploit those developments.