Sheffield and Jamaica were officially rated at thirty-two knots, but that number should not be treated as an absolute maximum. Royal Navy trials often avoided sustained forced draught, which increased boiler output at the price of greater wear, and the service had little incentive to advertise every performance margin of its benchmark designs. Belfast's robust hull, turbines and boilers illustrate machinery built for endurance in peace but capable of being pushed harder in combat. Using that reserve imposed additional boiler wear, so conserving machinery in peace and demanding more power in battle served different operating priorities.
Notable Point · 1:44:11-1:51:28
What a Royal Navy thirty-two-knot rating concealed
Conservative peacetime speed ratings left British cruisers with machinery margins they could exploit during wartime emergencies.