Type 81 Frigate (Tribal Class) (1961-1984) (RN)

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SKB
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Type 81 Frigate (Tribal Class) (1961-1984) (RN)

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Image
^ HMS Ashanti (F117), first ship of the Type 81 Tribal class.

Introduction
The Type 81, or Tribal class, was a class of seven general-purpose frigates for the Royal Navy designed during the 1950's that served throughout the 1960's and 1970's with limited service during the 1980's.

History
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.

Design
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 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 gun armament was 2 twin 4 inch WW2 standard mounts, then planning switched to arming them first with the twin 3 inch 70 caliber and then two single automatic 4 inch guns of the sort fitted the Chilean Admiralte Williams class. The automatic guns were rejected on account of weight and cost and the grounds they would have required a slightly larger hull. From the outset they were designed to carry the new GWS-20 Sea Cat anti-aircraft missile system but all except Zulu initially shipped single Mark 7 Bofors guns in lieu. In the event, budget restraints led to only Ashanti, Gurkha, Eskimo and Zulu being so fitted.

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 Rothesays were given further refits in preference to the Tribals and maintained in higher status reserve in the early 1980s limitations on defence spending.

Shortcomings
The costs for the Tribals escalated above the costs first envisaged, and the original order of ships, over twenty, was cancelled after the first seven ships had been completed. The ships were rather small, at 360 ft (110 m), which prevented much modernisation and were always going to be limited by the single-shaft propulsion. The class were still good warships in spite of outdated guns, described by some as 'guided flagpoles' if sometimes capable of 18rpm for the first 2 minutes, and proved the usefulness of the general purpose frigate concept and gas turbine propulsion, but the average unit costs, of the Type 81's completed in 1963-64 was half million pounds, more than the first 8 Leanders and the over 5 million cost of the first Tribal, HMS Ashanti completed in 1961 was far too high and limited the number built,(the original intent was to build 23 Type 81's) and guaranteed 1960's frigate development would be based on the more conservative steam powered, Type 12 as perfected in the excellent Type 12M Leander.The later Type 21 Royal Navy patrol frigate, was originally envisaged for a similar gunboat role to the Tribals East of Suez.

Service
The class served throughout the 1960's and into the 1970's fulfilling their designed general purpose "colonial gunboat" role. When change in British foreign policy made this role redundant they found themselves being pressed into service in home waters in the "Cod Wars" of the 1970's. They were not particularly suited to these duties however, as they had a hull form optimised for the calm, shallow water of the Persian Gulf and with only a single shaft were unable to manoeuvre with the Icelandic patrol vessels at close quarters.

All were decommissioned from the Royal Navy during the mid-to-late 1970's with the manpower crisis also attributing to the rapid removal of the class from service. They were however given a brief reprieve by the Falklands war, with 3 mothballed Tribals (Gurkha, Tartar and Zulu) being reactivated to cover ships deployed to the South Atlantic or undergoing long-term repairs after the conflict. The remaining units were cannibalised for spare parts to enable the 3 ships to be refitted. These ships were sold in 1984 to Indonesia.

Ships of the class
1. HMS Ashanti (F117) Commissioned 1961. Transferred to harbour training ship role in 1978. Sunk for target practise 1988.
2. HMS Tartar (F133) Commissioned 1962. Decommissioned 1984. Sold to Indonesia 1984, recommissioned as 'Hasanuddin'
3. HMS Nubian (F131) Commissioned 1962. Decommissioned 1981. Sunk for target practice 1987.
4. HMS Gurkha (F122) Commissioned 1963. Decommissioned 1984. Sold to Indonesia 1984, recommissioned as 'Wilhelmus Zakarias Yohannes'.
5. HMS Eskimo (F119) Commissioned 1963. Decommissioned 1980. Scrapped 1992. (Saved for target practise in 1986, but not used.)
6. HMS Mohawk (F125) Commissioned 1963. Decommissioned 1980. Scrapped 1982.
7. HMS Zulu (F124) Commissioned 1964. Decommissioned 1984. Sold to Indonesia 1984, recommissioned as 'Martha Khristina Tiyahahu'

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)
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)
Crew 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 inch (114 mm) Mark 5* Mod 1 guns
2 × single 40 mm Mark 7 Bofors guns, later;
2 × four-rail GWS-20 Sea Cat missile systems
2 × single 20 mm Oerlikon guns
1 × Mark 10 Limbo ASW mortar
Aircraft carried: 1x Westland Wasp helicopter

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SKB
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Re: Type 81 Frigate (Tribal Class) (1961-1984) (RN)

Post by SKB »

HMS Tartar was used in the 'Cod Wars'

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