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).

[3] The Turkish ships were fitted with the ASDIC sound detection system to locate submarines underwater[4] and a Type 286 search radar.

[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 & sank the German submarines U-409 in the Mediterranean north-east of Algiers on 12 July 1943 & U-767 while in company with the destroyers Fame & Havelock in the English Channel south-west of Guernsey on 18 June 1944.