HMS Implacable was the name ship of her class of two aircraft carriers built for the Royal Navy during World War II. Upon completion in 1944, she was initially assigned to the Home Fleet and attacked targets in Norway for the rest of the year. She was subsequently assigned to the British Pacific Fleet (BPF) where she attacked the Japanese naval base at Truk and targets in the Japanese Home Islands in 1945. The ship was used to repatriate liberated Allied prisoners of war (PoWs) and soldiers after the Japanese surrender, for the rest of the year. Implacable returned home in 1946 and became the Home Fleet's deck-landing training carrier, a role that lasted until 1950. She briefly served as flagship of the Home Fleet in 1950. During this time she participated in many exercises and made a number of port visits in Western Europe. She was placed in reserve in 1950 and converted into a training ship in 1952, and served as flagship of the Home Fleet Training Squadron. The ship was considered for a major modernisation in 1951–1952, but this was rejected as too expensive and time-consuming. Implacable was decommissioned in 1954 and sold for scrap the following year.
Design and description
The Implacable class had its origin as an improved version of the Illustrious-class aircraft carriers for the 1938 Naval Programme. They were designed to be faster, and to carry an additional dozen aircraft at the expense of reduced armour protection to remain within the available from the tonnage allowed by the Washington Naval Treaty.Friedman, p. 141 Implacable was long overall and at the waterline. Her beam was Friedman, p. 366 at the waterline and she had a draught of at deep load. The Implacable-class ships were significantly overweight and displaced at deep load.Brown 1977, p. 49 The ships had metacentric heights of at light load and at deep load as completed.Friedman, p. 151 Implacables complement was approximately 2,300 officers and ratings in 1945.Hobbs 2013, p. 109
The ships were equipped with four Parsons geared steam turbines, each driving one shaft using steam supplied by eight Admiralty 3-drum boilers.Chesneau 1980, p. 20 The turbines were designed to produce a total of , enough to give them a maximum speed of .Friedman, p. 367 On sea trials, Implacable reached speeds of with . She carried a maximum of of fuel oil which gave her a range of at .
The armoured flight deck had a maximum width of .Friedman, p. 154 A single hydraulic aircraft catapult was fitted on the forward part of the flight deck. The Implacable-class carriers were equipped with two lifts on the centreline, the forward of which measured and served only the upper hangar, and the aft lift () which served both hangars. The upper hangar was long and the lower hangar was long; both had a maximum width of . Both hangars had a height of only 14 feet which precluded storage of Lend-Lease Vought F4U Corsair fighters as well as many post-war aircraft and helicopters. Designed to stow 48 aircraft in their hangars, the use of a permanent deck park allowed the Implacable class to accommodate up to 81 aircraft. The additional crewmen, maintenance personnel and facilities needed to support these aircraft were housed in the lower hangar. The ships were provided with of petrol.Brown 1977, pp. 48–49; Friedman, p. 144
Armament, electronics and protection The ship's main armament consisted of sixteen quick-firing (QF) dual-purpose guns in eight twin-gun turrets, four in sponsons on each side of the hull. Unlike the Illustrious-class ships, the roofs of the gun turrets were flat and flush with the flight deck. The gun had a maximum range of .Campbell, pp. 52, 55 Her light anti-aircraft defences included five octuple mounts for QF 2-pounder ("pom-pom") anti-aircraft (AA) guns, two on the flight deck forward of the island, one on the aft part of the island and two in sponsons on the port side of the hull. A single quadruple 2-pounder mount was also fitted on the port side of the hull.Friedman, pp. 144, 367 The 2-pounder gun had a maximum range of .Campbell, p. 71 The ship was also fitted with 61 Oerlikon 20 mm autocannon in 19 single and 21 twin-gun mounts. These guns had a maximum range of , but some were replaced by 40 mm Bofors AA guns when the ships were transferred to the Pacific Theater as the 20 mm shell was unlikely to destroy a kamikaze before it hit the ship. The Bofors gun had a maximum range of .Campbell, pp. 67, 75 Two additional quadruple "pom-pom" mounts were added to Implacable before she joined the British Pacific Fleet in 1945. By the end of the war, she had 4 single Bofors guns, plus 17 twin and 17 single Oerlikon mounts. By April 1946 these had been reduced to 12 Bofors guns, 8 twin and 14 single Oerlikon guns.Friedman, pp. 149, 154
They were fitted with the Type 277 surface-search/height-finding radar on top of the bridge and a Type 293 target indicator radar on the foremast. The ships probably carried Type 279 and Type 281B early-warning radars, based on the radars fitted aboard the Illustrious-class carrier late in the war. In addition, Type 282 and Type 285 gunnery radars were mounted on the fire-control directors.Campbell, pp. 15–16, 18–19; Friedman, pp. 144–145, 149, 151; Hobbs 2013, pp. 111, 113
The Implacable-class ships had a flight deck protected by of armour. The sides of the hangars were either or . The ends of the hangars were protected by 2-inch bulkheads and the armour of the hangar deck ranged from in thickness. The waterline armour belt was thick, but only covered the central portion of the ship. The belt was closed by 1.5 to 2-inch transverse bulkheads fore and aft. The underwater defence system was a layered system of liquid- and air-filled compartments as used in the Illustrious class. The magazines for the 4.5-inch guns lay outside the armoured citadel and were protected by 2 to 3-inch roofs, 4.5-inch sides and 1.5 to 2-inch ends.Friedman, pp. 134, 139, 142–143
Construction and service
Implacable was laid down by Fairfield Shipbuilding and Engineering Co. at their shipyard in Clydeside on 21 February 1939, as Yard Number 672. Her construction was temporarily suspended in 1940–41, in favour of higher-priority ships needed to fight in the Battle of the Atlantic, before she was launched on 10 December 1942 by Queen Elizabeth. Captain Lachlan Mackintosh was appointed to command the ship in November 1943.McCart, p. 170 She was commissioned on 22 May 1944, and began sea trials which revealed a significant number of problems that required rectification, so the ship was not formally completed until 28 August. Implacable was assigned to the Home Fleet and was working up over the next several months while the Fairey Fireflies of 1771 Squadron flew aboard on 10 September.McCart, p. 171 The squadron was followed by the Fairey Barracuda torpedo bombers of 828 and 841 Squadrons that made up 2nd Naval TBR Wing later that month.Sturtivant, pp. 284, 309, 471
Her first mission was to locate the which had left its anchorage in Kaafjord in early October. Implacable departed Scapa Flow on 16 October, and a section of her Fireflies spotted the battleship off Håkøya Island near Tromsø two days later. No attack was mounted because the carrier lacked any single-seat fighters aboard to escort the strike aircraft, although they did damage a cargo ship before returning home. On 16 October, the Supermarine Seafires of 887 and 894 Squadrons of 24th Naval Fighter Wing landed aboard.Sturtivant, pp. 370, 386 In late October she participated in Operation Athletic off the Norwegian coast, where her aircraft sank six ships and damaged a German submarineRohwer, pp. 368–369 for the loss of one Barracuda,Hobbs 2013, p. 110 while conducting the Royal Navy's last wartime torpedo attack. On 1 November Captain Charles Hughes-Hallett relieved Mackintosh and assumed command of the ship. The Barracudas were replaced by the Seafires of 30th Naval Fighter Wing, which consisted of 801 and 880 Squadrons, on 8 NovemberSturtivant, pp. 165, 359, 473 and the Seafires provided air cover for minelaying operations by escort carriers from 11 to 21 November. The next day, Admiral Sir Henry Ruthven Moore, Commander-in-Chief of the Home Fleet, hoisted his flag in Implacable and the ship set sail to hunt for a convoy that had been reported near Alsten Island (Operation Provident) with the Seafires and Fireflies of 801, 880, and 1771 Squadrons aboard. Bad weather prevented aircraft from being launched until 27 November, but they located the convoy and sank two merchantmen, including , and damaged six others. MS Rigel was used as a German prisoner of war (POW) transport and the sinking resulted in more than 2,500 dead, mostly POWs. Upon her return to Scapa on 29 November, Moore lowered his flag, but Vice Admiral Sir Frederick Dalrymple-Hamilton, second in command of Home Fleet, hoisted his flag on 6 December for Operation Urbane, another minelaying operation during which her Fireflies helped to sink a German minesweeper. Dalrymple-Hamilton transferred his flag off Implacable when she returned to Scapa on 9 December. On 15 December she began a refit at Rosyth preparatory to her transfer to the British Pacific Fleet, which included augmenting her light AA armament.Brown 2009, p. 31; Hobbs 2013, p. 110; McCart, pp. 171–172
Upon its completion on 10 March 1945, 801, 828, 880, and 1771 Squadrons reembarked with a total strength of 48 Seafires, 21 Grumman TBF Avenger torpedo bombers and a dozen Fireflies, the largest air group aboard a British carrier thus far. Implacable departed six days later to join the BPF and arrived at Port Said, Egypt, on 25 March. While passing through the Suez Canal, a strong gust of wind forced her ashore and it took her escorting tugboats five hours to pull her off. Undamaged, she proceeded on her voyage and reached Sydney on 8 May 1945 (V-E Day).McCart, p. 173
Implacable arrived at the BPF's main operating base at Manus Island, in the Admiralty Islands, on 29 May. A week later Rear Admiral Sir Patrick Brind hoisted his flag in preparation for Operation Inmate, an attack on the Japanese naval base at Truk in the Caroline Islands that began on 14 June. Having flown 113 offensive sorties over the two days of the attack, with only one loss of a Seafire to enemy action, the carrier and her escorts returned to Manus Island on 17 June.Hobbs 2011, p. 211; McCart, pp. 173–174 On 30 June 8th Carrier Air Group was formed, absorbing No. 24 Naval Fighter Wing, to control all of the air units aboard Implacable.Sturtivant, p. 474