The class's ten-knot economical cruising speed became its main long-term weakness. Immediately after the First World War, that pace supported the endurance needed for imperial policing and presence missions and was one of the design's strengths. During the 1920s and early 1930s, improving machinery and faster operational expectations left it increasingly outpaced. The limitation complicated later development even though the C class suffered from much the same problem. A feature optimized for one strategic setting had become a liability as the tempo of naval operations changed.
Notable Point · 24:53-25:42
When economical cruising speed became a liability
The endurance that suited the D class to postwar station work came with a cruising-speed limitation that became more serious in the 1920s and 1930s.