I-class destroyer

For the World War I I-class Destroyers, see Acheron-class destroyer.

The I-class destroyers were a group of nine destroyers, including a flotilla leader, built for the Royal Navy during the 1930s. Four similar ships were ordered by the Turkish Navy, of which two were purchased for the Royal Navy, bringing the number of these ships in British service to 11—although three of the original ships had been lost by the time Inconstant and Ithuriel were commissioned. The I-class served in World War II and six were lost, with a seventh ship being written off.

HMS Imogen
Class overview
Name	I class
Operators	Royal Navy Turkish Navy
Preceded by	G and H class
Succeeded by	Tribal class
In commission	1937–1960
Completed	13
Lost	6
Scrapped	7
General characteristics (as built)
Type	Destroyer
Displacement	1,370 long tons (1,390 t) (standard) 1,888 long tons (1,918 t) (deep load)
Length	323 ft (98.5 m)
Beam	33 ft (10.1 m)
Draught	12 ft 5 in (3.8 m)
Installed power	34,000 shp (25,000 kW) 3 Admiralty 3-drum boilers
Propulsion	2 shafts; 2 geared steam turbines
Speed	36 knots (67 km/h; 41 mph)
Range	5,530 nmi (10,240 km; 6,360 mi) at 15 knots (28 km/h; 17 mph)
Complement	137 (peacetime), 145 (wartime)
Sensors and processing systems	ASDIC
Armament	4 × 1 - QF 4.7-inch (120 mm) Mk IX guns 2 × 4 - 0.5-inch (12.7 mm) machine guns 2 × 5 - 21-inch (533 mm) torpedo tubes 20 × Depth charges, 1 rack and 2 throwers 60 mines (minelayers only)

Design

The I-class was a repeat of the preceding H class, except that they had ten torpedo tubes (two banks of five) instead of eight. They incorporated the new bridge and wheelhouse layout as tested in Hero and Hereward (except the flotilla leader Inglefield). Inglefield also had a larger tripod foremast, her sisters having pole masts. The extra weight of the torpedo tubes and the fitting of minesweeps and depth charge gear (previous vessels carried one or the other) on the same hull as the H class, caused a loss of stability, needing ballast when bunker levels were low.

All ships were fitted for minesweeping and with depth charges and Asdic for anti-submarine (A/S) work and were capable of conversion to minelayers. For this, they landed 'A' and 'Y' 4.7 inch guns, the torpedo tubes and their minesweeps, allowing carriage of up to 60 mines but only four ships were used like this (see below).

Turkish ships

The Turkish I-class ships were of a similar design to their British counterparts but shipped only eight torpedoes (two banks of four) like the British H class.

Wartime modifications

Early war modifications involved replacing the after bank of torpedoes with a QF 12-pounder (3 inch/76 mm) anti-aircraft (AA) gun, cutting down the after funnel and mainmast to improve its field of fire and adding a pair of QF 20 mm Oerlikon guns in the bridge wings. Radar Type 286, a metric wavelength surface-warning set, was added as it became available and the ineffective multiple 0.5 in (13 mm) Vickers machine guns were replaced with Oerlikons; the central tube was deleted from the torpedo launchers to lessen topweight. Icarus lost 'Y' gun to stow extra depth charges (for a total load of 110) and their mortars. Surviving ships received a third pair of Oerlikons, added abreast the searchlight position and the 12-pounder was deleted to increase depth charge stowage. In some ships, 'A' gun was replaced with a Hedgehog forward-throwing A/S weapon but this alteration seems to have been reversed at a later stage. Ilex, Intrepid, Impulsive and Isis had 'B' gun removed and two QF 6-pounder 10 cwt (2.25 inch/57 mm L/47) guns were added on the twin mounting Mark I* along with a Hedgehog, the former for anti-E boat work.

Inglefield later had the second bank of torpedo tubes re-instated but like her sisters, the central tube was removed. A 4 in (100 mm) AA gun was added instead of 'X' gun and she had six Oerlikons. Type 291 radar was later added at the foremast head as well as Huff-Duff in some ships.

The ex-Turkish ships were modified along similar lines to their I-class sisters. Inconstant later received Type 270 radar, a centimetric wavelength target-indication set, in place of the director and rangefinder on the bridge. Again, eventually, six Oerlikons were carried.

Ships

Construction data

Ship	Builder	Laid down	Launched	Commissioned	Fate
Icarus	John Brown & Company, Clydebank	9 March 1936	26 November 1936	3 May 1937	Sold for scrap, 29 October 1946
Ilex			28 January 1937	7 July 1937	Sold for scrap, 1947
Imogen	Hawthorn Leslie & Company, Hebburn	18 January 1936	30 October 1936	2 June 1937	Sank after a collision with the cruiser Glasgow, 16 July 1940
Imperial		29 January 1936	11 December 1936	30 June 1937	Severely damaged by air attack, 29 May 1941, sunk by torpedoes from Hotspur
Impulsive	J. Samuel White, Cowes	9 March 1936	1 March 1937	29 January 1938	Sold for scrap, 22 January 1946
Inglefield	Cammell Laird & Company, Birkenhead	29 April 1936	15 October 1936	25 June 1937	Sunk by German radio-controlled glide bomb, 25 February 1944
Intrepid	J. Samuel White, Cowes	6 January 1936	17 December 1936	29 July 1937	Sunk by German bombers, 26 September 1943
Isis	Yarrow & Company, Scotstoun	5 February 1936	12 December 1936	2 June 1937	Mined and sunk off Normandy beaches, 20 July 1944
Ivanhoe		12 February 1936	11 February 1937	24 August 1937	Mined and sunk off Texel, 1 September 1940

Turkish ships

Four ships were ordered for the Turkish Navy in 1938. Upon the outbreak of war, two were purchased by the British but two were delivered to Turkey in 1942 as the Sultanhisar and the Demirhisar.

Construction data

Ship	Builder	Laid down	Launched	Completed	Fate
Inconstant (ex-Muavenet)	Vickers, Barrow	24 May 1939	24 February 1941	24 January 1942	Acquired 14 November 1941, returned to Turkey 9 March 1946, sold for scrap, 1960
Ithuriel (ex-Gayret)			15 December 1940	3 March 1942	Bombed at Bône 28 November 1942 and beached; sold for scrap, 25 August 1945
Sultanhisar	William Denny, Dumbarton	21 March 1939	17 December 1940	28 June 1941	Delivered to Turkey in 1942, decommissioned 1960
Demirhisar		1939	1941	1942	Delivered to Turkey in 1942, decommissioned 1960

Bibliography

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