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, 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 then in short supply so not 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. The larger Rivers were too expensive to produce at the required rate and needed larger slipways. The was developed in late-1942, which was derived from the River and designed for prefabricated construction. The Castle was developed from a proposal by Smith's Dock Company – who had designed the Flower-class – for a stretched Flower. The result was a smaller version of the Loch for shipyards that only built corvettes using mainly traditional methods.
The design was approved in May 1943 and 96 Castles were ordered from yards in the UK and Canada. Fifteen British and all 37 Canadian ships were later cancelled; Canada receiving twelve British-built ships instead. The UK completed a further five as convoy rescue ships for its Merchant Navy. Four became weather ships after the war.

Design

The Castle resembled later Flowers with an extended forecastle and mast behind the bridge, but was 135 tons heavier and 47 feet longer. The Admiralty Experiment Works at Haslar developed an improved hull form which, in combination with the increased length, made the Castle at least half a knot faster than the Flower despite using the same engine. The Castle also had a single-screw. A lattice mainmast was used instead of the pole version fitted to the Flowers.
Construction used mainly traditional methods with as much welding as possible. Scantling was based on the Flower, but lightened in some areas. The wireless office, the radar office, and the lattice mast were installed as prefabricated units.
The Castle was armed with a Squid anti-submarine mortar, directed by Type 145 and 147B ASDIC. The Flower used the older Hedgehog mortar and could not be fitted with Squid. The first operational Type 147 and Squid were installed aboard HMS Hadleigh Castle in September 1943.
In place of the BL 4-inch Mk IX main gun, the Castles had the new QF 4-inch Mk XIX gun on a High-Angle/Low-Angle mounting which could be used against aircraft as well as surface targets such as submarines.

In service

The Castle was criticized for being barely fast enough to fight German Type VII submarines and difficult to handle at low speed.

Ships

Royal Canadian Navy

The following vessels were all originally built for the Royal Navy, but were transferred to the RCN on completion. All their pennant numbers, as well as their names, were changed when transferred.
  • HMCS Arnprior
  • HMCS Bowmanville, sold to Republic of China as cargo ship, but taken over by the Communist People's Liberation Army Navy after the end of the Chinese Civil War and rearmed with Soviet guns, entering PLAN service as Guangzhou.
  • HMCS Copper Cliff
  • HMCS Hespeler
  • HMCS Humberstone
  • HMCS Huntsville
  • HMCS Kincardine
  • HMCS Leaside
  • HMCS Orangeville, sold to Republic of China as cargo ship, but taken over by the ROC Navy on 29 June 1950 and rearmed with US guns, entering ROCN service as De An
  • HMCS Petrolia
  • HMCS St. Thomas
  • HMCS Tillsonburg, sold to Republic of China as cargo ship, but taken over by ROCN on 29 June 1950 and rearmed with US guns, entering ROCN service as ''Kao An''

Royal Navy

The first of the Castle-class were the prototypes Hadleigh Castle and Kenilworth Castle, ordered on 9 December 1942; another 12 vessels were also ordered on 9 December, also under the 1942 War Programme. The remaining eighty-one ships were all ordered for the RN under the 1943 War Programme, of which thirty were completed. Fifty-one of these ships were cancelled late in 1943.
NamePennantHull builderOrderedLaid downLaunchedCommissionedPaid offFate
K355Smiths Dock Company9 Dec 19424 Apr 194321 Jun 194318 Sep 1943Aug 1946Scrapped, Jan 1959
K420Smiths Dock Company9 Dec 19427 May 194317 Aug 194322 Nov 19431948Scrapped, 20 Jun 1959
K689Fleming & Ferguson9 Dec 1942
22 Jul 194329 Feb 194419 June 19441947Scrapped 1958
K412John Lewis & Co. Ltd9 Dec 19421 Jul 194311 Jan 194430 May 19441950Scrapped 22 May 1959
K690John Lewis & Co. Ltd9 Dec 194226 Aug 194322 May 194429 September 19441947Scrapped Mar 1956
K696John Lewis & Co. Ltd9 Dec 194230 Sep 19435 Aug 194430 December 1944Declared constructive total loss, 13 Feb 1945
K413John Crown & Sons Ltd9 Dec 194225 Jun 194325 Apr 194431 Jan 19451947Scrapped, 31 Oct 1960
K529John Crown & Sons Ltd9 Dec 19422 Nov 194330 Oct 194412 May 1945Aug 1945Scrapped, Apr 1958
K691Fleming & Ferguson9 Dec 194210 Sep 194314 Apr 194415 Sep 19441947Scrapped, 20 Jun 1959
Maiden CastleK443Fleming & Ferguson9 Dec 194219438 Jun 1944November 1944Became convoy rescue ship Empire Lifeguard before completion; Scrapped, 22 Jul 1955
K447A. & J. Inglis9 Dec 194230 Sep 194312 Apr 19446 Sep 1944Transferred to Canada as HMCS Humberstone 1944; Sold for mercantile service 1947
K530A. & J. Inglis9 Dec 194230 Sep 194320 Jul 194410 Dec 19441950Became the weather ship Weather Reporter 1957
K450Ferguson Shipbuilders9 Dec 19423 Jun 194312 Feb 194429 June 1944Transferred to Canada as HMCS Tillsonburg in 1944; Sold for mercantile service 1947; Sold to Republic of China as Kao An 1952
K695Ferguson Shipbuilders9 Dec 1942194312 Jun 1944Oct 1944Completed as convoy rescue ship Empire Rest
K405George Brown & Co.19 Jan 194319433 Oct 19441957Broken up Dec 1958
K594George Brown & Co.19433 Oct 1944completed 1945 as convoy rescue ship Empire Shelter
K383Henry Robb, at Leith20 Apr 19431 Sep 194331 Dec 1943Mar 1956Broken up 10 Jul 1958
K378Henry Robb, at Leith25 May 194313 Nov 194311 Mar 1944to Canada as HMCS Hespeler, 1944; Sold for mercantile service 1946
K491Henry Robb, at Leith23 Jul 194326 Jan 194410 May 1944to Canada as HMCS Orangeville, 1944; Sold for mercantile service 1947; to Republic of China Navy 1951 as Te An
K389Blyth Dry Dock22 Apr 19431 Sep 19435 April 19441947Broken up 16 Mar 1956
K397Blyth Dry Dock27 May 194327 Nov 194320 June 19441947Broken up 3 Aug 1959
K473Smiths Dock, at Middlesbrough23 Jun 194328 Dec 194318 May 194422 Nov 1945to Canada as HMCS St. Thomas, 1944; sold for mercantile service 1946
K393Smiths Dock, at Middlesbrough25 Aug 194326 Jan 19443 Jul 194417 Feb 1946to Canada as HMCS Kincardine; sold for mercantile service 1946
K405Smiths Dock, at Middlesbrough23 Sep 194310 Mar 19445 Sep 194416 Nov 1945to Canada as HMCS Leaside; sold for mercantile service 1946
York CastleFerguson Brothers, Port Glasgow194420 Sep 1944completed Feb 1945 as convoy rescue ship
Blyth Dry Dock29 June 194324 Feb 194415 Aug 1944to Canada as HMCS Copper Cliff, 1944; Sold for mercantile service 1947, then became Chinese 1949
K384William Pickersgill & Sons23 Jan 194322 Apr 194312 Oct 194315 Feb 1944Nov 1956broken up 5 Jun 1958
K693William Pickersgill & Sons23 Jan 194323 Jun 194326 Nov 194313 Jul 19441946broken up 9 Aug 1960
K446William Pickersgill & Sons23 Jan 194312 Aug 194326 Jan 19448 Oct 1944to Canada as HMCS Bowmanville, 1944; Sold for mercantile service 1946, then became Chinese Kuang Chou 1949
K692Harland and Wolff23 Jan 194321 Jun 194311 Dec 194310 Mar 19441946broken up 6 Sep 1960
K449Harland and Wolff23 Jan 194321 Jun 194311 Jan 194410 Jun 1944Feb 1946Became weather ship Weather Monitor in 1959
K398Harland and Wolff23 Jan 194321 Jun 19438 Feb 194426 Jun 194414 Mar 1946to Canada as HMCS Arnprior, 1944; transferred to Uruguay as Montevideo
K536Fleming & Ferguson23 Jan 194319448 Sep 1944Jan 1945Completed as convoy rescue ship
K453Harland and Wolff23 Jan 194321 June 194324 Feb 194414 Jul 19448 Mar 1946to Canada as HMCS Petrolia, 1944; Sold for mercantile service 1946
K399Ailsa Shipbuilding Company23 Jan 194329 April 194313 Dec 19437 Apr 1944Aug 1956Broken up Jun 1958
K461Ailsa Shipbuilding Company23 Jan 19431 Jun 194324 Feb 194415 Jun 194415 Feb 1946to Canada as HMCS Huntsville, 1944; Sold for mercantile service 1947
K386S P Austin & Son Ltd2 Feb 194331 May 194325 Nov 194324 Nov 19441947Became the weather ship Weather Adviser in 1960
K387Barclay Curle2 Feb 194323 Apr 194319 Aug 194318 Nov 19441946Scrapped 24 February 1956
K379Caledon Shipbuilding & Engineering Company2 Feb 194312 Mar 194331 Jul 194317 Nov 19431947Scrapped 14 June 1958
K388Caledon Shipbuilding & Engineering Company2 Feb 19436 May 194328 Sep 194325 Feb 19441947Scrapped March 1961
K416Caledon Shipbuilding & Engineering Company2 Feb 19436 August 194323 Feb 19449 Jun 1944Sunk by U-482 on 1 Sep 1944
K362Swan Hunter6 Feb 194317 March 194321 Jun 19438 Nov 19431947Scrapped 14 May 1958
K372Swan Hunter6 Feb 19438 April 194316 Jul 194324 Feb 19441946Became the weather ship Weather Surveyor in 1960
K374Swan Hunter6 Feb 19435 May 194316 Aug 194324 Apr 1944Transferred to Norway on completion and renamed HNoMS Tunsberg Castle; Sunk by mine 12 Dec 1944

Notes: from the previous order placed for a Modified Flower-class corvette named Amaryllis.
Two of those ordered 3 March 1943, three ordered 4 May 1943 and two ordered 10 July 1943 were all cancelled, as were all thirty-six ordered from Canadian shipyards on 15 March 1943.

Royal Norwegian Navy

  • – HMS Shrewsbury Castle was loaned to the Royal Norwegian navy on 17 April 1944. On 12 December 1944, she hit a mine and sank.

Cancelled

Fifteen ships ordered for the Royal Navy from UK shipyards as part of the 1943 Programme were all cancelled on 31 October 1943:Caldecot Castle – ordered 19 January 1943 from John Brown & Company, Clydebank.Dover Castle – ordered 19 January 1943 from A. & J. Inglis, Glasgow.Dudley Castle – ordered 19 January 1943 from A. & J. Inglis, Glasgow.Bere Castle – ordered 23 January 1943 from John Brown & Company, Clydebank.Calshot Castle – ordered 23 January 1943 from John Brown & Company, Clydebank.Monmouth Castle – ordered 23 January 1943 from John Lewis & Sons, Aberdeen.Rhuddlan Castle – ordered 23 January 1943 from John Crown & Sons, Sunderland.Thornbury Castle – ordered 23 January 1943 from Ferguson Brothers, Port Glasgow.Appleby Castle – ordered 3 March 1943 from Austin, at Sunderland.Tonbridge Castle – ordered 3 March 1943 from Austin, at Sunderland.Norwich Castle – ordered 4 May 1943 from John Brown & Company, Clydebank.Oswestry Castle – ordered 4 May 1943 from John Crown & Sons, Sunderland.Pendennis Castle – ordered 4 May 1943 from John Crown & Sons, Sunderland.Alton Castle – ordered 10 July 1943 from Fleming & Ferguson, Paisley.Warkworth Castle – ordered 10 July 1943 from Fleming & Ferguson, Paisley.
The following ships were ordered on 15 March 1943 for the Royal Navy from Canadian shipyards for completion between May 1944 and June 1945, but were all cancelled in December 1943:Aydon CastleBarnwell CastleBeeston CastleBodiam CastleBolton CastleBowes CastleBramber CastleBridgnorth CastleBrough CastleCanterbury CastleCarew CastleChepstow CastleChester CastleChristchurch CastleClare CastleClavering CastleClitheroe CastleClun CastleColchester CastleCorfe CastleCornet CastleCowes CastleCowling CastleCriccieth CastleCromer CastleDevizes CastleDhyfe CastleDunster CastleEgremont CastleFotheringay CastleHelmsley CastleMalling CastleMalmesbury CastleRaby CastleTrematon CastleTutbury Castle
  • ''Wigmore Castle''

Castles sunk or destroyed in action

  • was sunk by northwest of Ireland on 1 September 1944.
  • HNoMS Tunsberg Castle was sunk by a mine near Båtsfjord, Norway on 12 December 1944.
  • was hit by a torpedo from in the Barents Sea on 13 February 1945. She was towed by to the Kola Inlet but later capsized.

U-boats sunk by Castles

  • was sunk by,,,,, and on 6 March 1944
  • was sunk in the north-west of Ireland by and on 9 September 1944
  • was sunk south of Ireland by,, and on 11 November 1944
  • was sunk in the Barents Sea by on 9 December 1944
  • was sunk north-west of the Azores by on 27 December 1944
  • was sunk in the Barents Sea by and on 17 February 1945
  • was sunk in the Bay of Biscay by and on 10 April 1945

Film appearance

The final third of the film The Cruel Sea is set on the Castle-class corvette Saltash Castle.

Post-war conversions

Three were converted to passenger/cargo ships for the Union Steamship Company of British Columbia and were known as the White Boats. They were operated from 1946 to 1958 but were heavy on fuel and had limited cargo capacity, for example they could not carry cars in the hold.
  • SS Camosun III – ex-HMCS St. Thomas, HMS Sandgate Castle
  • SS Chilcotin – ex-HMCS Hespeler, HMS Guildford Castle
  • SS Coquitlam II – ex-HMCS Leaside, HMS ''Walmer Castle''