Like corvettes, sloops of that period were specialised convoy-defence vessels. However, while corvettes were based on a mercantile design with triple expansion engines, sloops were conventional naval vessels with turbine engines. Sloops were larger and faster with a heavy armament of high angle 4-inch guns which had superior anti-aircraft fire control via the Fuze Keeping Clock, while retaining excellent anti-submarine capability. They were designed to have a longer range than a destroyer at the expense of a lower top speed, while remaining capable of outrunning surfaced Type VII and Type IX U-boats.