J-, K- and N-class destroyer

HMS Kashmir
Class overview
Operators	Royal Navy Royal Australian Navy Polish Navy Royal Netherlands Navy Indonesian Navy
Preceded by	Tribal class
Succeeded by	L and M class
Subclasses	J, K, N
Completed	24
Cancelled	1
Lost	15
Retired	9
General characteristics as per Lenton
Displacement	1,690 tons (1,717 tonnes) standard 2,330 tons full load (2,367 tonnes)
Length	356.5 ft (108.7 m) o/a
Beam	35.75 ft (10.90 m)
Draught	12.5 ft (3.8 m) full
Propulsion	2 x Admiralty 3-drum boilers, Parsons geared steam turbines, 40,000 shp on 2 shafts
Speed	36 kt (32 kt full load displacement)
Range	5,500 nmi at 15 kt 1,500 nmi at 32 kt
Armament	6 x QF 4.7 inch (120-mm) Mk.XII guns, twin mount CP Mk.XIX 4 x QF 2 pounder Mk.VIII (40 mm) L/39, quad mount Mk.VII 8 x 0.5 in Mk.III (12.7mm) Vickers, quad mount Mk.III 10 (2x5) tubes for 21 in torpedo Mk.IX
Notes	planned 183 (218 in leader)
General characteristics (N class)
Displacement	1,773 tons standard (1,801 tonnes) 2,384 tons full load (2,422 tonnes)
Complement	183 (218 in leader)
Armament	6 x QF 4.7 inch (120-mm) Mk.XII L/45 guns, twin mount CP Mk.XIX 1 x QF 4 in Mk.V (102 mm), mount HA Mk.III 4 x QF 2 pounder Mk.VIII (40 mm), quad mount Mk.VII 4 x QF 20 mm Oerlikon, single mounts P Mk.III 4 x QF 0.5 in Mk.III (12.7mm) Vickers, twin mount Mk.V 5 (1x5) tubes for 21 in torpedoes Mk.IX
Notes	Other characteristics as per above

The J, K and N class was a class of 24 destroyers of the Royal Navy launched in 1938. They were a return to a smaller vessel, with a heavier torpedo armament, after the Tribal class that emphasised guns over torpedoes. The ships were built in three flotillas or groups, eight each of ships with names beginning with "J", "K" and "N". The flag superior of the pennant numbers changed from "F" to "G" in 1940.

Design history

The design was intended as a smaller follow on from the preceding Tribal class, and incorporated one radical new idea that was a departure from all previous Royal Navy destroyer designs. That was the adoption of a two boiler room layout. This reduced hull length and allowed for a single funnel, both reducing the profile and increasing the arcs of fire of the light Anti-aircraft (A/A) weapons. However, this also increased vulnerability, as there were now two consecutive large compartments with the resultant risk of a single well placed hit flooding both and resulting in a total loss of boiler power. This illustrates somewhat the Admiralty's attitude to the expendable nature of destroyers. During Prewar trials "...On a light displacement Jackal attained 37.492 knots, on the Arran mile in 60 fathoms, 34.37 knots deep. Jupiter in 75 fathoms made 33.835 knots light, 33.045 knots deep displacement."

A significant advance in construction techniques was developed by naval architect Albert Percy Cole. Instead of going for transverse frame sections being unnecessarily strong, held together by weak longitudinals, Cole went for extra strong longitudinals and weaker transverse frames.

Another advancement was changes to the bow design. The bow form was also modified from that of the preceding Tribal class design; the clipper bow replaced by a straight stem with increased sheer. This change was not a success and as a consequence these ships were very wet forwards. This shortcoming was rectified from the S class onwards by returning to the earlier form.

Despite the vulnerability of the boiler layout, the design was to prove compact, strong and very successful, forming the basis of all Royal Navy destroyer construction from the O class up to the last of the C class of 1943-1945.

The armament was based on that of the Tribals, but replaced one twin QF 4.7 in (120 mm) Mark XII (L/45) gun on mounting CP Mk.XIX with an additional bank of torpedo tubes. These mountings were capable of 40° elevation and 340° of training. Curiously, 'X' mounting was positioned such that the blind 20° arc was across the stern, rather than the more logical forward position where fire was obscured by the bridge and masts anyway. This meant that they were unable to fire dead astern. With the tubes now pentad, a heavy load of 10 Mk.IX torpedoes were now carried. The A/A armament remained the same, consisting of a quadruple QF 2 pdr gun Mark VIII on mounting Mk.VII and a pair of quadruple 0.5 in Vickers machine guns, and was later improved by the replacing the quadruple machine guns with 20mm Oerlikons. These ships, when completed, had a comparatively heavy close range AA armament. Fire control arrangements also differed from the Tribals, and the dedicated high-angle (H/A) rangefinder director was not fitted, instead only a 12 ft (3.7 m) rangefinder was carried behind the usual destroyer Director Control Tower (DCT). In the event, the rangefinder was heavily modified to allow it to control the main armament for A/A fire, and was known as the "3 man modified rangefinder". These ships used the Fuze Keeping Clock HA Fire Control Computer.

The N class were ordered in 1940 as repeats of the J design, after delays and cost over-runs associated with the larger and more complicated L and M class. The only design change was to mount the 'X' 4.7-in mounting in the more logical position with the 20° training blindspot forward. While building, the same early wartime modifications as the Js and Ks were applied, with a pair of twin power-operated 0.5 in machine gun turrets briefly carried on the quarterdeck before being replaced by single 20 mm Oerlikons.

Modifications

Church service aboard HMS Javelin, August 1940. 4-inch QF Mk V anti-aircraft gun is in background

In 1940 and 1941, to improve the anti-aircraft capabilities, all ships had their aft torpedo tubes removed and replaced with a single 4 inch gun QF Mark V on mounting HA Mark III. The relatively ineffective multiple 0.5-inch (13 mm) machine guns were replaced with single 20 mm Oerlikon guns, with a further pair added abreast the searchlight platform amidships. The high-speed destroyer mine sweeps were replaced with a rack and two throwers for 45 depth charges and Radar Type 286 air warning was added at the masthead alongside Type 285 fire control on the H/A rangefinder-director.

In 1942 the 4 in gun was removed and the torpedoes returned to all surviving vessels. The 20 mm Oerlikon guns were replaced with twin mountings (except those on the quarterdeck) and Radar Type 291 replaced the Type 286. Jervis, Kelvin, Nerissa and Norman had the searchlight replaced with the "lantern" for centimetric target indication Radar Type 271; Javelin and Kimberley having the lighter Type 272 fitted at the truck of the foremast. Napier, Nizam and Norseman (and later, Norman) had American Radar SG1 fitted at the head of a new lattice foremast, Norman replacing her Type 271 set with a single 40 mm Bofors gun. By the end of the war, the surviving J and K ships carried a lattice mast with Radar Type 293 target indication at the truck and Type 291 air warning at the head.

Service

Being amongst the Royal Navy's most modern and powerful destroyers at the outbreak of war, they were heavily committed. As a result, losses were heavy and of 24 ships built, six J, six K and one N class were war losses.

Ships

• ‡ = flotilla leader

J class

Pennant number	Name	Builder	Laid down	Launched	Completed	Fate
F00	Jervis ‡	Hawthorn Leslie & Company, Hebburn	26 August 1937	9 September 1938	12 May 1939	Sold for scrapping 1949
F22	Jackal	John Brown & Company, Clydebank	24 September 1937	25 October 1938	31 March 1939	Bombed off Mersa Matruh on 11 May 1942 and scuttled by Jervis following day.
F34	Jaguar	William Denny & Brothers, Dumbarton	1937-11-25	1938-11-22	1939-09-12	Torpedoed by German U-boat U.652 off Sollum, 26 March 1942
F46	Juno (ex-Jamaica)	Fairfield Shipbuilding & Engineering Company, Govan	1937-10-15	1938-12-08	1939-08-25	Bombed and sunk south of Crete, 21 May 1941
F53	Janus	Swan Hunter & Wigham Richardson, Wallsend	29 September 1937	11 October 1938	5 August 1939	Torpedoed and sunk off Anzio by German aircraft, 23 January 1944
F61	Javelin (ex-Kashmir)	John Brown	11 October 1937	21 December 1938	10 June 1939	Sold for scrapping 1949
F72	Jersey	J. Samuel White, Cowes	1937	26 September 1938	28 April 1939	Mined off Valetta 2 May 1941, broke in two and sank 2 days later
F85	Jupiter	Yarrow & Company, Scotstoun	28 September 1937	27 October 1938	25 June 1939	Hit a Dutch mine during the battle of the Java Sea 27 February 1942 and sank following day
-	Jubilant	-	-	-	-	Ordered March 1937, cancelled December 1937

K class

Pennant number	Name	Builder	Laid down	Launched	Completed	Fate
F01	Kelly ‡	Hawthorn Leslie	26 August 1937	25 October 1938	23 August 1939	Bombed by German aircraft and sunk south of Crete, 23 May 1941
F28	Kandahar	Denny	1938-01-18	1939-03-21	1939-10-10	Mined off Tripoli 19 December 1941 and sunk by gunfire from Jaguar following day
F12	Kashmir (ex-Javelin)	John I. Thornycroft & Company, Woolston	1937-11-18	1939-04-04	1939-10-26	Bombed by German aircraft and sunk south of Crete, 23 May 1941
F37	Kelvin	Fairfield	1937-10-05	1939-01-19	1939-11-27	Sold for scrapping 1949
F45	Khartoum	Swan Hunter	1937-10-27	1939-02-06	1939-11-06	Sank in Perim Harbour after an exploding torpedo air vessel set off a fire which reached the aft magazine. 1940-06-23
F50	Kimberley	Thornycroft	1938-01-17	1939-06-01	1940-02-21	Sold for scrapping 1949
F64	Kingston	White	1937-10-06	1939-01-09	1939-09-14	Seriously damaged by the Italian battleship Littorio during the Second Battle of Sirte, 22 March 1942. Later (11 April 1942) bombed by German aircraft while in dry dock in Valletta and written off as constructive total loss. Expended as blockship off Malta
F91	Kipling	Yarrow	26 October 1937	19 January 1939	22 December 1939	Bombed and sunk by German aircraft off Mersa Matruh, 11 May 1942

N class

Those N class of the Royal Australian Navy were manned by, and commissioned into, that force, but remained the property of the British Government.

Pennant number	Name	Builder	Laid down	Launched	Completed	Fate
Royal Netherlands Navy
G84	Noble	Denny	10 July 1939	17 April 1941	20 February 1942	To the Netherlands as Van Galen 1942, sold for scrapping 1957
G16	Nonpareil	Denny	1940-05-22	1941-06-25	1942-10-30	To Netherlands as Tjerk Hiddes 1942. To Indonesia as Gadjah Mada 1951, sold for scrapping 1961
Royal Australian Navy
G97	Napier ‡	Fairfield	1939-07-26	1940-05-22	1940-12-11	Sold for scrapping 1945
G02	Nestor	Fairfield	1939-07-26	1940-07-09	1941-02-12	Bombed by Italian aircraft 15 June 1942 and sunk by depth charges from Javelin
G38	Nizam	John Brown	1939-07-27	1940-07-04	1940-12-19	Sold for scrapping 1955
G49	Norman	Thornycroft	1939-07-27	1940-10-30	1941-09-29	Sold for scrapping 1958
G25	Nepal (ex-Norseman)	Thornycroft	1939-09-09	1941-12-04	1942-05-29	Sold for scrapping 1955
Polish Navy
G65	Nerissa	John Brown	26 July 1939	7 May 1940	12 February 1941	To Poland as Piorun 1940, returned as HMS Noble 1946, sold for scrapping 1955