The Black Swan class and Modified Black Swan class were two classes of sloop of the Royal Navy and Royal Indian Navy. Twelve Black Swans were launched between 1939 and 1943, including four for the Royal Indian Navy; twenty-five Modified Black Swans were launched between 1942 and 1945, including two for the Royal Indian Navy; several other ships were cancelled.
History
Like corvettes, sloops of that period were specialised convoy-defence vessels. Corvettes were based on a mercantile design with triple expansion engines, sloops were conventional naval vessels with turbines. 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.
In World War II, Black Swan-class sloops sank 29 U-boats. The most famous sloop commander was Captain Frederic John Walker. His sloop became one of the most successful submarine hunters, taking part in the sinking of eleven U-boats. After the war, sloops continued in service with the Royal Navy, Egyptian Navy, Indian Navy, Pakistan Navy and the West German Navy. In April 1949, was attacked on the Yangtze River by the Communist People's Liberation Army. Several Black Swan sloops fought in the Korean War.
Black Swan class
Royal Navy
The first two ships were built under the 1937 Programme, being ordered from Yarrow and Company, Scotstoun, on 1 January 1938. The second pair was built under the 1939 Programme, being ordered from Furness Shipbuilding Company on 21 June 1939. A further ten RN ships were ordered under the 1940 War Programme on 13 April 1940; however six of these (the orders placed with White of Cowes, Thornycroft at Woolston, and Swan Hunter on Tyneside for two ships each) were subsequently replaced by orders for an equal number of escort destroyers.
There were incremental improvements as the building developed, and the Woodcock and Wren when completed were practically indistinguishable from the Modified Black Swan class.
{| class="wikitable sortable plainrowheaders" style="font-size:97%;"
|+ List of Black Swan-class sloops of the Royal Navy
|-
! scope="col" | Name
! scope="col" | Pennant
! scope="col" | Builder
! scope="col" | Laid Down
! scope="col" | Launched
! scope="col" | Commissioned
! scope="col" | Fate
|-
! scope="row" |
! scope="row" | L18<br />later U18
|Yarrow, Scotstoun
|26 May 1938