When 25 knots stopped being enough

The ships could carry as much as 508 tons of coal, enough for 3,400 nautical miles at an economical 10 knots. Their escort mission depended on speed as well as endurance. Destroyers kept getting faster, while triple-expansion machinery left the scout cruisers at about 25 knots. A cruiser that could not keep pace with the craft it was meant to lead and protect was being overtaken by its own mission. Turbines might have pushed them beyond 30 knots, although that change alone would not necessarily have transformed their First World War service.