The I-class ships were improved versions of the preceding H class. They displaced 1,370 long tons (1,390 t) at standard load and 1,888 long tons (1,918 t) at deep load. The ships had an overall length of 323 feet (98.5 m), a beam of 33 feet (10.1 m) and a draught of 12 feet 6 inches (3.8 m). They were powered by two Parsons geared steam turbines, each driving one propeller shaft, using steam provided by three Admiralty three-drum boilers. The turbines developed a total of 34,000 shaft horsepower (25,000 kW) and were intended to give a maximum speed of 35.5 knots (65.7 km/h; 40.9 mph). The ships carried enough fuel oil to give them a range of 5,500 nautical miles (10,200 km; 6,300 mi) at 15 knots (28 km/h; 17 mph). Their crew numbered 145 officers and ratings.[1]
Inconstant was laid down as TCG Muavenet for the Turkish Navy by Vickers Armstrong at their Barrow-in-Furness shipyard on 24 May 1939, purchased in September 1939 by the Royal Navy, launched on 24 February 1941 and commissioned on 24 January 1942. The ship participated in the assault on Madagascar in May 1942, and attacked and sank the German submarines U-409 in the Mediterranean north-east of Algiers on 12 July 1943 and U-767 while in company with the destroyers Fame and Havelock in the English Channel south-west of Guernsey on 18 June 1944. Inconstant was returned to Turkey on 9 March 1946 and renamed Muavenet. She was discarded in 1960.
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