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)

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.

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).

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.

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.

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.

• Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of all Fighting Ships of the Royal Navy (Rev. ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8.
• English, John (1993). Amazon to Ivanhoe: British Standard Destroyers of the 1930s. Kendal: World Ship Society. ISBN 0-905617-64-9.
• Friedman, Norman (2006). British Destroyers & Frigates: The Second World War and After. Annapolis, Maryland: Naval Institute Press. ISBN 1-86176-137-6.
• Hodges, Peter & Friedman, Norman (1979). Destroyer Weapons of World War 2. Greenwich: Conway Maritime Press. ISBN 978-0-85177-137-3.
• Lenton, H. T. (1998). British & Empire Warships of the Second World War. Annapolis, Maryland: Naval Institute Press. ISBN 1-55750-048-7.
• Lyon, Hugh & Chumbley, Stephen (1995). "Turkey". In Chumbley, Stephen (ed.). Conway's All the World's Fighting Ships 1947-1995. Annapolis, Maryland: Naval Institute Press. ISBN 1-55750-132-7.
• March, Edgar J. (1966). British Destroyers: A History of Development, 1892-1953; Drawn by Admiralty Permission From Official Records & Returns, Ships' Covers & Building Plans. London: Seeley Service. OCLC 164893555.
• Rohwer, Jürgen (2005). Chronology of the War at Sea 1939–1945: The Naval History of World War Two (Third Revised ed.). Annapolis, Maryland: Naval Institute Press. ISBN 1-59114-119-2.
• Smith, Peter C. (2005). Into the Minefields: British Destroyer Minelaying 1918–1980. Barnsley, UK: Pen & Sword Books. ISBN 1-84415-271-5.
• Whitley, M. J. (1988). Destroyers of World War Two: An International Encyclopedia. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-326-1.

Wikimedia Commons has media related to I class destroyer.