Black Swan Class (1939) Sloop

The Black Swan Sloops began to join the Fleet just as WW2 broke out and convoy escorts were in critical shortage.

They followed on from the previous Egret Class (1938) and were similar with the main change being replacement of the "Y"  turret twin 4in AA with a quadruple 2pdr AA mounting. This enhanced the short range Anti-Air defence at a small cost to the long range anti-air guns.

During the wartime changes the aft quad 2 pdr was deleted to allow additional depth charges and mortars to be carried. Single 20mm mountings were replaced by twin mountings, and later some 20mm guns replaced by 40mm units.

The Class was very suited to escort work and proved very successful. However they were too complex to put into large scale production to meet the critical need for convoy escorts. (So the numerical shortage was met by increased production of less suitable, but cheaper and less complex Corvettes and Frigates.) The Black Swan's high standard of anti-submarine and anti-air firepower  was a welcome addition to a convoy screen.

The Black Swans became most successful when used as the "Capital Ship" of group of convoy escorts, which could be used to reinforce selected convoys under heavy attack. These convoy escort groups were based around a Black Swan rounded out with additional Corvettes, Frigates and smaller rescue units. 

Later when they became available, an escort carrier would be added to the group to provide air cover. So an escort group was a powerful addition to the defensive strength of any convoy to which it was attached.

The class was built in two groups. As the war progressed some early changes were made to first groups armament outfit. These changes were built into the second group during construction. Naturally further changes were made to all ships as hostilities continued.

The ten ships of this class were followed by a further 30 vessels known as the Modified Black Swan Class (1942).  

By the time the Black Swans were launched the term Sloop was an incorrect designation. Sloop had been officially replaced with the term Escort in 1937. However the term Sloop remained in general but unofficial use so I have used it here to show the vessels similarity to their predecessors.

The term Sloop was officially dropped in 1937 when Escort Sloops were re-rated as Escort Vessels, but the term continued in unofficial use. An initial requirement to conduct minesweeping duty was reduced as the roles of minesweeping and convoy escort diverged. The required endurance was determined as the longest passage probable as a convoy escort which was the UK to Freetown, 3,500 miles plus a margin for operations. Say about 5000 miles at 10kts.


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This page last edited - 04 February, 2013.

Copyright Ian M King, except where otherwise indicated.