O and P-class destroyer

The O and P class was a class of destroyers of the British Royal Navy. Ordered in 1939, they were the first ships in the War Emergency Programme, also known as the 1st and 2nd Emergency Flotilla, respectively. They served as convoy escorts in World War II, and some were subsequently converted to fast second-rate anti-submarine frigates in the 1950s.

HMS Oribi in 1946
Class overview
Name	O and P class
Operators	Royal Navy  Pakistan Navy  Turkish Navy
Preceded by	L and M class
Succeeded by	Q and R class
Subclasses	4 inch O, 4.7 inch O, P
Completed	16
Lost	4
Retired	12
General characteristics P class[1]
Type	Destroyer
Displacement	1,690 tons (1,717 tonnes) standard 1,640 tons (1,666 tonnes) 2,250 tons (2,286 tonnes) full load
Length	345 ft (105 m) o/a
Beam	35 ft (10.7 m)
Draught	9 ft (2.7 m)
Propulsion	2 x Admiralty 3-drum water-tube boilers, Parsons geared steam turbines, 40,000 shp on 2 shafts
Speed	36.75 kt
Range	3,850 nmi at 20 kt
Armament	5 × QF 4 in Mk.V (102 mm L/45), single mounts HA Mk.III 4 × QF 2 pdr Mk.VIII (40 mm L/39), quad mount Mk.VII Up to 6 x QF 20 mm Oerlikon, single mount P Mk.III 4 (1x4) tubes for 21 inch torpedoes Mk.IX 4 × throwers and 2 x racks for 70 depth charges
General characteristics (4.7 inch O class)
Displacement	1,610 tons (1,636 tonnes) 2,270 tons (2,306 tonnes) full load
Complement	176 (217 in leader)
Armament	4 × QF 4.7-inch (120-mm) Mk IX guns, single mounts CP Mk.XVIII 1 × QF 4 in Mk.V (102 mm L/45), mount HA Mk.III 4 × QF 2 pdr Mk.VIII (40 mm L/39), quad mount Mk.VII Up to 6 x QF 20 mm Oerlikon, single mount P Mk.III 4 (1x4) tubes for 21 in torpedoes Mk.IX
Notes	Other characteristics as per P class
General characteristics (4 inch O class)
Displacement	1,540 tons (1,564 tonnes) 2,220 tons (2,255 tonnes) full load
Armament	4 × QF 4 in Mk.V (102 mm L/45), single mount HA Mk.III 4 × QF 2 pdr Mk.VIII (40 mm L/39), quad mount Mk.VII Up to 6 x QF 20 mm Oerlikon, single mount P Mk.III 8 (2x4) tubes for 21 in torpedoes Mk.IX Up to 60 mines (where fitted-for)
Notes	Other characteristics as per P class

Design

The O and P class were based on the hull and machinery of the preceding J class, but with more sheer forward to counter the poor riding qualities of the Js. These ships used the Fuze Keeping Clock HA Fire Control Computer.^[2]

O class

The O-class ships were built in two groups of four. The first group had 4.7 inch guns. They were in low-angle mounts which could elevate to only 40 degrees, and were additionally fitted with a 4-inch anti-aircraft gun in place of one set of torpedo tubes. The second group had 4-inch (102 mm) guns in high-angle mounts and were fitted to act as minelayers; they could be recognized by the flat "beaver tail" stern over which the mines were dropped.

When carrying mines they had to land Y gun, their torpedo tubes and depth charges. The designed anti-aircraft armament was one quadruple QF 2-pounder "pom pom" and a pair of quadruple 0.5-inch Vickers A/A machine guns. The latter proved to be outdated, and were replaced by 20 mm Oerlikon guns as they became available, with a total of six single mounts eventually being carried.

P class

The P class were repeats of the O class, armed entirely with 4 inch guns, in high-angle mounts fitted with a new tall design of shield which did not require the ships to lose a set of torpedo tubes to take on further AA guns.

Ships

O class

All ships survived the war. Five of them were involved in the Battle of the Barents Sea, Onslow being badly damaged. After the battle, the ships were refitted with tall lattice masts instead of the normal mast.

Construction data for 4.7-inch-armed ships

Name	Pennant number	Builder	Laid down	Launched	Completed	Fate
Onslow[a] (ex-Pakenham)	G17	John Brown	1 July 1940	31 March 1941	8 October 1941	To Pakistan 1949 as Tippu Sultan, sold out
Offa	G29	Fairfield	15 January 1940	11 March 1941	20 September 1941	To Pakistan 1949 as Tariq, sold for scrap in 1959.
Onslaught (ex-Pathfinder)	G04		14 January 1941	9 October 1941	19 June 1942	To Pakistan 1951 as Tughril, sold out.
Oribi (ex-Observer)	G66		15 January 1940	14 January 1941	5 July 1941	To Turkey 1946 as Gayret, sold out.

1. Flotilla leader

Construction data for 4-inch-armed ships

Name	Pennant number	Builder	Laid down	Launched	Completed	Fate
Obdurate	G39	Denny	25 April 1940	19 February 1942	3 September 1942	Sold for scrap in 1964 at J Cashmore's, Newport, Monmouthshire.
Obedient	G48		22 May 1940	30 April 1942	30 October 1942	Sold for scrap - 1964.
Opportune	G80	Thornycroft	28 March 1940	21 February 1942	14 August 1942	Sold for scrap - 1955.
Orwell	G98		20 May 1940	2 April 1942	17 October 1942	Converted to Type 16 frigate 1952, sold for scrap – 1965.

All of the O-class ships with 4-inch armament were fitted for minelaying.

P class

They served mainly in the Mediterranean, where four ships were lost.

Construction data for 4-inch-armed ships

Name	Pennant number	Builder	Laid down	Launched	Completed	Fate
Pakenham[a] (ex-Onslow)	G06	Hawthorn Leslie	6 February 1940	28 January 1941	4 February 1942	Disabled by gunfire from Italian Navy torpedo boats Cassiopea and Cigno off Marsala 16 April 1943 in the Battle of the Cigno Convoy, abandoned and scuttled by sister ship HMS Paladin following the action
Paladin	G69	John Brown	22 July 1940	11 June 1941	December 1941	Converted to Type 16 frigate 1954, sold for scrap in 1962
Panther	G41	Fairfield	15 July 1940	28 May 1941	12 December 1941	Bombed and sunk by German Junkers Ju 87 'Stuka' aircraft in Scarpanto Strait on 10 September 1943.
Partridge	G30		3 June 1940	5 August 1941	22 February 1942	Torpedoed by German Submarine U-565 off Oran, 18 December 1942.
Pathfinder	G10	Hawthorn Leslie	5 March 1940	10 April 1941	13 April 1942	On 11 February 1945, Pathfinder was hit by a Japanese bomber off Ramree, and was taken out of service. She was used as an aircraft target, sold for scrap in 1948.
Penn	G77	Vickers Armstrongs	26 December 1939	12 February 1941	10 February 1942	Sold for scrap - 1949.
Petard	G56			27 March 1941	15 June 1942	Converted to Type 16 frigate, sold for scrap 1967.
Porcupine	G93			10 June 1941	31 August 1942	Torpedoed by German submarine U-602 in the Mediterranean on 9 December 1942 which broke her in two; she was never repaired, but hulked as Pork and Pine, sold for scrap, 1947.

1. Flotilla leader

See also

• Type 16 frigate: postwar conversion of some O and P class vessels into second-rate fast anti-submarine frigates.