Tribal-class frigate

The Type 81, or Tribal class, were ordered and built as Sloops to carry out similar duties to the immediate post war Improved Black Swan Sloops and Loch class frigates in the Gulf. In the mid 1960's the seven Tribals were reclassified as second class general-purpose frigates for the same reasons as the 21C reclassification of the USN Littoral Combat ships, to maintain frigate numbers. After the British withdrawal from East of Suez in 1971 the Tribals operated in the Nato North Atlantic sphere with the only update the fitting of Seacat missiles to all by 1977, limited by their single screw and low speed of 24 knots. In 1979-80 age and crew and fuel shortages, saw them transferred to the stand by squadrons, three being reactivated in 1982 in the Falklands crisis for training and West Indian guardship duties.

Country Name Origin Year
United Kingdom - UK (Great Britain) 1950
Country Name Operational Year Retirement Year
Iceland 1958 1958 View

They were the first class of the Royal Navy to be designed from the start to operate a helicopter and the first small escorts to carry a long-range air search radar, the Type 965 with a single 'rake' AKE-1 antenna. They were armed with two 4.5-inch (114 mm) Mark 5 main guns salvaged from scrapped Second World War destroyers. Although these mountings were refurbished with Remote Power Control (RPC) operation, they still required manual loading on an exposed mounting. Originally the intended gun armament was two twin 4-inch (102 mm) Second World War standard mounts, then planning switched to arming them first with the twin 3-inch (76 mm) 70 caliber and then two single automatic 4-inch guns of the sort fitted to the Chilean Almirante Williams class. The automatic guns were rejected on account of weight, space and cost. From the outset they were designed to carry the new GWS-21 Sea Cat anti-aircraft missile system but all except Zulu initially shipped single Mark 7 Bofors guns in lieu. The rest of the class were fitted with Sea Cat in the 1970s using surplus missile systems, leftover from Battle-class destroyers and County-class destroyer refits.

The Tribals were the first modern RN ships designed to use a combination of power sources, a feature which had been trialled with limited success in the 1930s in the minelayer HMS Adventure. An additive mix of steam and gas turbine called "COmbined Steam and Gas" COSAG was used. This gave the rapid start-up and acceleration of a gas turbine engine coupled with the cruising efficiency and reliability of the steam turbine. They would cruise on the steam plant and use both systems driving the same shaft for a high-speed "boost". They suffered however from being single-shaft vessels which severely limited manoeuvrability, acceleration and deceleration. The single screw proved significantly limiting when they were used in the 1970s Cod Wars in terms of manoeuvering in ramming manoeuvers, for and against, Icelandic coast guard cutters. The cramped awkward nature of the helicopter pad and handling provision was also exposed in the 1976 Cod War and was a major reason that some Rothesay-class frigates were given further refits in preference to the Tribals and maintained in higher status reserve in the early 1980s limitations on defence spending.

Ships in Class

Pennant Name Builder Laid Down Launched Accepted into service Commissioned Estimated building cost Fate
F117 Ashanti (a) Yarrow & Co Ltd, Glasgow
(b) Associated Electrica Industries Ltd, Manchester
15 January 1958 9 March 1959 November 1961 23 November 1961 £5,315,000 Sunk as target 1988
F131 Nubian (a) HM Dockyard, Portsmouth
(b) Associated Electrica Industries Ltd, Manchester
7 September 1959 6 September 1960 November 1962 9 October 1962 £4,360,000 Sunk as target 1987
F122 Gurkha (a) JI Thornycroft & Co Ltd,Southampton
(b) JI Thornycroft & Co Ltd, Southampton (steam and gas turbines)
(b) Parsons Marine Turbine Co Ltd, Wallsend-on-Tyne (gearing)
3 November 1958 11 July 1960 February 1963 13 February 1963 £4,865,000 Indonesian 332 KRI Wilhelmus Zakarias Yohannes
F119 Eskimo (a) JS White & Co Ltd, Cowes, Isle of Wight
(b) JS White & Co Ltd, Cowes, Isle of Wight (steam and gas turbines)
(b) Fairfield Shipbuilding and Engineering Co Ltd, Govan, Glasgow (gearing)
22 October 1958 20 March 1960 February 1963 21 February 1963 £4,560,000 Sunk as target 1986
F133 Tartar (a) HM Dockyard, Devonport
(b) Vickers-Armstrongs (Engineers) Ltd, Barrow-in-Furness (steam turbines and gearing)
(b) Yarrow and Co Ltd, Glasgow (gas turbine)
22 October 1959 19 September 1960 April 1963 26 February 1962 £4,300,000 Indonesian 333KRI Hasanuddin
F125 Mohawk (a) Vickers-Armstrongs (Shipbuilders) Ltd, Barrow-in-Furness
(b) Associated Electrical Industries Ltd, Manchester (gas turbine)
(b) Vickers-Armstrongs (Engineers) Ltd, Barrow-in-Furness (steam turbines and gearing)
23 December 1960 5 April 1962 December 1963 29 November 1963 £4,750,000 Sold for scrap
F124 Zulu (a) Alex Stephen & Sons, Ltd, Linthouse, Glasgow
(b) JI Thornycroft & Co Ltd, Southampton (steam and gas turbines)
(b) Parsons Marine Turbine Co Ltd, Wallsend-on-Tyne (gearing)
13 December 1960 3 July 1962 April 1964 17 April 1964 £5,100,000 Indonesian 331 KRI Martha Khristina Tiyahahu

The Tribals were designed during the 1950s as a response to the increasing cost of single-role vessels such as the Type 14s. They were first such 'multi role' vessels for the Royal Navy. They were designed specifically with colonial 'gunboat' duties in mind, particularly in the Middle East. They were therefore designed to be self-contained warships with weapon and sensor systems to cover many possible engagements, air conditioning to allow extended tropical deployment and such 'modern' habitability features as all bunk accommodation (as opposed to hammocks). The fitting of gas turbine boost engines was specifically intended to allow the frigates to almostly instantly leave ports and naval bases in the event of nuclear war, rather than have to spend four to six hours to flash up the steam boilers. The G6 gas turbine proved reliable and was generally used to leave port during the frigates career and paved the way for gas turbine propulsion to become universal in the RN within 30 years.

Name: Type 81 or Tribal class
Operators:  Royal Navy
 Indonesian Navy
Preceded by: Blackwood class
Succeeded by: Type 21
Completed: 7
Retired: 4
General characteristics 
Type: Frigate
Displacement: 2,300 long tons (2,300 t) standard
2,700 long tons (2,700 t) full load
Length: 360 ft 0 in (109.73 m) oa
350 ft 0 in (106.68 m) pp
Beam: 42 ft 3 in (12.88 m)
Draught: 13 ft 3 in (4.04 m)
17 ft 6 in (5.33 m) (propellers)[2]
Propulsion: Single-shaft COSAG
1 Steam turbine 12,500 shp (9,300 kW)
1 Metrovick G-6 gas turbine 7,500 shp (5,600 kW)
Speed: 27 knots (50 km/h; 31 mph) (COSAG)
Range: 4,500 nautical miles (8,300 km; 5,200 mi) at 12 knots (22 km/h; 14 mph)
Complement: 253
Sensors and
processing systems:
Radar type 965 air-search
Radar type 993 low-angle search
Radar type 978 navigation
Radar type 903 gunnery fire-control
Radar type 262 GWS-21 fire-control
Sonar type 177 search
Sonar type 170 attack
Sonar type 162 bottom profiling
Ashanti and Gurkha;
Sonar type 199 variable-depth
Armament: 2 × single 4.5 in (114 mm) Mark 5* Mod 1 guns
2 × single 40 mm Mark 7 Bofors guns, later;
2 × four-rail GWS-20 Sea Cat missilesystems
2 × single 20 mm Oerlikon guns
1 × Mark 10 Limbo ASW mortar
Aircraft carried: 1 × Westland Wasp helicopter

End notes