Castle-class corvette

The Castle-class corvette was an ocean going convoy escort developed by the United Kingdom during the Second World War. It was the follow-on to the Flower-class corvette, and designed to be built in shipyards that were producing the Flowers. The Castle-class was a general improvement over the smaller Flowers which were designed for coastal rather than open ocean use.

The Castle-class corvettes started appearing in service during late 1943.

Background

In mid-1939, the Admiralty ordered 175 Flower-class corvettes for protecting shipping on the west coast of Britain as well as the Western Approaches. They were designed to be built in large numbers in small shipyards without propulsion and other components (mainly gearboxes, but also guns) then in short supply so not to compete with other warships for construction. By the time the Flowers began entering service in late-1940, due to their long range they were required to undertake missions beyond coastal waters. The Flowers were unsuited for open-ocean escort in the North Atlantic, especially in poor weather; they lacked speed, endurance, and habitability but became the mainstay of the Mid-Ocean Escort Force protecting convoys crossing the Atlantic.

The Royal Navy recognized the limitations of the Flower and began designing an open-ocean escort in November 1940, which became the River-class frigate. The larger Rivers were too expensive to produce at the required rate and needed larger slipways.