Tribal-class speed, oil, and turbine trials

With Jackie Fisher as First Sea Lord, the Navy sought the River class's practical capabilities at much higher speed. Oil-fired boilers and steam turbines were mandatory, and the ships were capable of more than 33 knots. The work went to Armstrong Whitworth, Cammell Laird, Hawthorn Leslie, J. S. White, Thornycroft, William Denny and Palmer's, giving the Navy several builders' responses to the same machinery requirements. Thornycroft's Tartar, Amazon and Nubian were particularly fast examples. Nubian later supplied the after half of Zubian. The programme allowed variations in funnels and armament, including 12-pounder and 4-inch gun arrangements with two 18-inch torpedo tubes. At close to a thousand tons, the Tribals were substantially larger than the 550-580-ton Rivers, even where their framing was lighter. Their high fuel consumption and varying strength require individual comparisons, but the demand for a fast fleet screen gave the experiments an operational purpose.