Military Wiki
Type 21 frigate
HMS Antelope (F170) MOD 45140138.jpg
HMS Antelope was sunk in the Falklands War
Class overview
Name: Type 21 Amazon
Builders: Yarrow Shipbuilders,
Vosper Thornycroft
Operators: Naval Jack of Pakistan.svg Pakistan Navy
 Royal Navy
Preceded by: Type 12M Leander
Succeeded by: Type 22 Broadsword
Subclasses: Niteroi-class frigate
Alvand-class frigate
In commission: 11 May 1974
Completed: 8
Active: 6
Lost: 2
General characteristics
Type: Frigate
As built:
  • 2,750 long ton (standard)
    3,250 tons (full load)

After strengthening:

  • 2,860 tons (standard)
    3,360 tons (full load)
Length: 360 ft (110 m) (waterline)
384 ft (117 m) (overall)
Beam: 41.8 ft (12.7 m)
Draught: 19 ft (5.8 m)
Propulsion: COGOG on 2 shafts;
2 × Tyne cruise turbines: 8,500 shp (6,300 kW)
2 × Olympus boost turbines: 50,000 shp (37,000 kW)
Speed: 32 knots (59 km/h; 37 mph) 37 knots burst speed (Olympus)
18 knots (33 km/h; 21 mph) (Tyne)
Range: 4,000 nmi (7,400 km; 4,600 mi) at 17 knots (31 km/h; 20 mph)
3,500 nmi (6,500 km; 4,000 mi) at 18 knots (33 km/h; 21 mph)
1,200 nmi (2,200 km; 1,400 mi) at 30 knots (56 km/h; 35 mph)
Complement: 13 officers, 164 ratings
Sensors and
processing systems:
1 × Radar Type 992Q low-level search
1 × Radar Type 978 navigation
2 × Radar Type 912 fire-control
Sonar Type 184M and 162M

Later additions:

  • 4 × launchers for MM38 Exocet surface-surface missiles
  • 2 × 12.75 in (324 mm) 3-tube STWS-1 anti-submarine torpedo launchers

Pakistani modifications:

Aircraft carried: 1 × Wasp or Lynx
Aviation facilities: Flight deck and hangar

HMS Amazon during Exercise RIMPAC 86

The Type 21 frigate, or Amazon-class frigate, was a Royal Navy general-purpose escort that was designed in the late 1960s, built in the 1970s and served throughout the 1980s into the 1990s.


In the mid-1960s, the Royal Navy had a requirement for a replacement for the diesel-powered Leopard-class and Salisbury-class frigates. While the Royal Navy's warships were traditionally designed by the Ministry of Defence's Ship Department based at Bath, private shipyards (in particular Vosper Thorneycroft) campaigned for the right to design and build a ship to meet this requirement. Vospers claimed that, by ignoring what they claimed to be the conservative design practices followed by the MoD team at Bath, they could deliver the new frigate at a significantly lower price (£3.5 million compared with the £5 million price of the contemporary Leander class), while being attractive to export customers.[1][2]

The class was ordered under political and Treasury pressure for a relatively cheap, yet modern, general purpose escort vessel which would be attractive to governments and officers of South America and Australasia -the traditional export markets of British shipyards. It was also envisaged as an out-of-area RN gunboat that would retain UK presence in those areas, as well as the Caribbean and the Gulf; essentially replacing the diesel Types Type 41, Type 61 and COSAG Type 81 with smaller crewed vessels. The RN staff disliked the idea and would have preferred, like many USN Admirals, to continue to develop steam types - in the RN's case, the Leander class, which was regarded as an especially successful and quiet anti-submarine hunter, but was seen by the politicians as dated and by the Treasury and export-oriented shipyards as too expensive to market. The development of Vosper's own export designs, the Mk 5 for Iran and the Mk 7 for Libya, increased the pressure on the Admiralty to accept this line of naval development, which seemed to offer a cheap export frigate with a range of 6000 nm, a top speed of 37 knots, a superficially good armament of the new Mark 8 4.5 inch gun, facilities for a Westland Wasp helicopter, anti-ship missiles and two triple lightweight Seacat missile launchers. When plans for the new Libyan frigate, Dat Assawari, were finalised in 1968, the Admiralty board accepted its paper specifications were unanswerable and they would have to allow the shipyards to develop a low cost fill in a/s and general purpose version for the RN that would be stretched and fully gas turbine powered rather than CODAG like the Mk 5 and Mk 7. In reality, it was a much more difficult design, with the RN requiring the extra internal weight of the Computer Assisted Action Information System (CAAIS) computer command systems and the lack of heavy diesels or a steam plant low in the hull to balance the heavy top weight of CAAIS. It would provide the shipyards with experience in building fully gas turbine powered ships and provide them with useful work for the shipyards while the Type 42 destroyer and Type 22 frigate would not be ready until the mid-to-late 1970s. As the Admiralty design board were busy with the latter, the Type 21 project was given to private shipyards Vosper Thornycroft and Yarrow. The unmistakably yacht-like and rakish lines were indicative of their commercial design. Their handsome looks combined with their impressive handling and acceleration lent itself to the class nickname of Porsches.

The original development of the Type 21 design was a combined RN/RAN project which in its final 1968 form had a very different sensor fit of the US Edo sonar fitted in Canadian 205 frigate updates and in Dutch Leander and different radar/ C3 with AS-1 Plessy for a Medium Range AW surveillance capability and probably adoption of similar fire control used in the last two RAN River Class, HMAS Swan and Torrens and the Daring Destroyer update of Vampire and Vendetta M22,[3] are relevant, and probably also involved RNZN. Non adoption by the Australasian navies reflected limited growth potential and end of the RN stationing significant forces East of Suez.

Attempts continued to sell frigates derived from the Type 21 to export customers, including Argentina,[1] while a broad-beam derivative armed with vertical-launch Sea Wolf surface to air missiles offered to Pakistan in 1985.[4]

The first of the eight built, Amazon, entered service in May 1974.


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These ships were the Royal Navy's first privately designed warships for many years. They were also the first design to enter service with the Royal Navy to be solely powered by gas-turbine engines, with two Rolls-Royce Tynes for cruising and two Rolls-Royce Olympus for high speeds arranged in a Combined gas or gas (COGOG) arrangement.[1] The design made use of large amounts of alloy in the superstructure to lower the amount of topweight. Worries later surfaced about its resilience to fire, particularly following a major fire on Amazon in 1977 during which aluminium ladders distorted, preventing fire-fighting teams from reaching the blaze, and its ability to withstand blast damage. Later warships reverted to using steel.[5]

As delivered, the Type 21s were armed with a single 4.5 inch Mark 8 naval gun forward, and a four-round launcher for the Sea Cat surface-to-air missile aft. The Italian Selenia Orion-10X lightweight fire control radar was adopted to control both the gun and the Sea Cat missile (as the GWS-24 system) in an effort to save weight. A Type 992Q air/surface radar was fitted, but a long-range air-search radar was not provided. A hangar and flight deck were provided for a single helicopter, at first the Westland Wasp. The CAAIS was provided to integrate the ship's weapons and sensor systems and provide the crew with all the relevant information they required to fight the ship, as and when they needed it.[1][6]

In terms of automation, systems integration and habitability, they were well in advance of many of the ships that they replaced, such as the Type 81 frigate and Rothesay-class frigate - the latter's basic design could be traced back to 1945. However although the T21 has the full 64k CAAIS of the more capable group 3 Leander - Seawolf conversion and first 4/T22 its control and automatic response in controlling the Mk 8 gun and Seacat, in the T21 represented only a training capability ( other than possibly in the anti missile role as the Mk 8s ability to operate automatically was useful as a counter to Soviet missiles and Exocet) given the Mk 8s high unrealiability, modest 25rpm of fire, rarely sustained in the early version and limited fire arcs with only 55 degree elevation compared with the 70-90 degree high elevation of the Leander 4.5 twin or the Mk ^ twin 3/70 or Vickers N5 single 4inch.


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When they entered service, the Type 21s were immediately criticized for being woefully under-armed. A program was put in hand to increase their firepower by fitting four French-built MM38 Exocet anti-ship missiles. These were sited in front of the bridge screen aft of the forecastle, displacing the Corvus countermeasure launchers to amidships. This improvement was quickly carried out to all ships of the class except Antelope and Ambuscade; the latter was fitted with Exocet in 1984/5. The Exocets were located in two pairs and the missiles would deploy across the ship and clear the opposite side of the vessel to their launchers in flight. This differed from the later Type 22 frigates, where deployment of the missiles was to the same side of the vessel as the missile pairs were fitted.

Intensive Royal Navy studies of the modernisation potential of the class in the mid and late 1970s revealed that the class lacked the space and weight to incorporate both a single Seawolf quad system and the new 2010 bow sonar,[7] which could be combined and refitted into broadbeam Leanders, and therefore by 1979 it was decided not give the Type 21 a mid life refit and pay the class of early.[8]

The Westland Wasp, a single-role torpedo-carrying helicopter, was replaced by the vastly more capable multi-mission Westland Lynx when it became available. As and when ships came in for refit, ship-launched anti-submarine torpedoes were also fitted, in the form of two STWS-1 triple-tube launchers capable of firing United States USN/NATO-standard Mark 44 or Mark 46 torpedoes. After the Falklands War, two more 20mm Oerlikon guns were mounted, one each side of the hangar, to provide extra close-in armament on some ships of the class.


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Criticism was levelled at the performance of the type in the Falklands conflict. The ships developed cracks in their decks due to the different expansion properties of steel and aluminium. This was a vulnerability particularly demonstrated under the severe weather conditions they encountered in the South Atlantic. Steel reinforcing plates were eventually fitted down the sides of the ships. Built to an exacting budget and design specification (and although carrying obsolete anti-aircraft weaponry), they distinguished themselves in a theatre for which they were not designed.

The class was also criticised for being overcrowded - at 384 ft (117 m), they had 177 crewmen compared to 436 ft (133 m) and just 185 crewmen for the modern Type 23 frigate. This was important at a time when the Royal Navy was facing a manpower shortage. The standard of accommodation for the officers was better than the RN average and the senior ratings enjoyed separate cabins – unlike the petty officers of the Type 42 destroyer of the same era, who slept in bunk rooms. The ratings' accommodation was also improved, with four-man sleeping berths leading off from the communal mess deck; again, far better than those of the Type 42 destroyer. In essence, the standard of accommodation and fitting were better, especially for officers, because it was a design intended to attract export orders. It is very little more than a stretched version of the MK 7 Vospers frigate built for third world Libya and, other than the fitting of CAAIS, with its electronic and intended weapon fit essentially the same as the Mk 7 prototype in type or level of sophistication. Higher automation and the new Mk 8 4.5 inch automatic gun combined with, in many ways, a much simpler electronic fit than the Leanders or Type 42, the new Type 21 class lacked both the long range radar, the Type 965, carried by most UK warships or the Limbo mortar and it associated sonar. Inevitably, that meant a much smaller crew than the Leanders, with little capability to modernise (owing to its small size) and already being close to its topweight limit; the Type 21's days were numbered. The several hundred tons of ballast that had to carried low down meant that the frigates could not usually achieve their planned 35 knots speed for any long distance, but the ships were all still good for a dramatic 37 knot burst speed, with two ships claiming to have exceeded 40 knots on more than one occasion. Nevertheless, these ships were regarded favorably by their crews and proved to be highly maneuverable and reliable assets in a navy suffering depletion in the number of modern escort hulls.


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Excepting Amazon, all the class took part in the 1982 Falklands War as the 4th Frigate Squadron. They were heavily involved, performing extensive shore-bombardment missions and providing anti-submarine and anti-aircraft duties for the task force. On 10 May HMS Alacrity and Arrow probed through Falkland Sound at night courageously searching for minefields which might have impeded landings and operations, almost as expendable hulls. Alacrity engaged and sank an Argentine naval supply vessel in the Sound. On exiting the Sound at daybreak they were attacked by the ARN submarine San Luis which fired two torpedoes, one hit HMS Arrows submarine towed decoy (as intended) and the other bounced off Arrows bottom, having failed to arm itself. Two vessels were lost: Ardent was hit by bombs dropped by Argentine aircraft on 21 May and was consumed by fire; Antelope was hit by bombs on 23 May, one of which was set off by the bomb disposal team attempting to defuse it on 24 May, causing the ship to catch fire, setting off her magazines resulting in her breaking her back and sinking.

Sale to Pakistan

The six surviving Type 21 frigates were sold to Pakistan in 1993–1994. The class was renamed by the Pakistani Navy as the Tariq class, after the first vessel that was acquired, the PNS Tariq, formerly Ambuscade. All six ships remain in service, as of 2011. They have had their Sea Cat launcher removed, as well as their Exocet missiles. Three of the ships had their Exocet missiles replaced by the more capable US-made Harpoon missile, the other three were fitted with the Chinese 6-cell LY-60N Hunting Eagle surface-to-air missile system.[9]


"A contract was awarded to Vosper Thornycroft on 27 February 1968 for the design of a patrol frigate to be prepared in full collaboration with Yarrow Ltd."[10] They were "designed to replace the Leopard- and Salisbury-class frigates. Initial cost was to be £3.5 million but Amazon actually cost £16.8 million."[11]

Pennant Name Hull builder Ordered Laid down Launched Accepted into service[12] Commissioned Est. building cost[13] Fate
F169 Amazon Vosper Thornycroft, Woolston 26 March 1969 [14] 6 November 1969 [14] 26 April 1971 [14] 19 July 1974 [15] 11 May 1974 [14] £16.8M [15] To Pakistan as Babur
F170 Antelope Vosper Thornycroft 11 May 1970 [14] 23 March 1971 [14] 16 March 1972 [14] 30 June 1975 [15] 16 July 1975 [14] £14.4M [16] Bombed by Argentine A-4 Skyhawks on 23 May 1982 and sank following day in San Carlos Water
F172 Ambuscade Yarrow Shipbuilders, Scotstoun 11 November 1971 [14] 1 September 1971 [14] 18 January 1973 [14] 23 August 1975 [15] 5 September 1975 [14] £16.5M [15] To Pakistan as Tariq
F173 Arrow YSL 11 November 1971 [14] 28 September 1972 [14] 5 February 1974 [14] 16 May 1975 [15] 29 July 1976 [14] £20.2M [15] To Pakistan as Khaibar
F171 Active Vosper Thornycroft 11 May 1970 [14] 21 July 1971 [14] 23 November 1972 [14] 2 June 1977 [15] 17 June 1977 [14] £24.1M [15] To Pakistan as Shah Jahan
F174 Alacrity YSL 11 November 1971 [14] 5 March 1973 [14] 18 September 1974 [14] 2 April 1977 [15] 2 July 1977 [14] £23.8M [15] To Pakistan as Badr
F184 Ardent YSL 11 November 1971 [14] 26 February 1974 [14] 9 May 1975 [14] 10 September 1977 [15] 14 October 1977 [14] £26.3M [15] Bombed by Argentine A-4 Skyhawks on 21 May 1982 in San Carlos Water and sank following day in Grantham Sound
F185 Avenger YSL 11 November 1971 [14] 30 October 1974 [14] 20 November 1975 [14] 15 April 1978 [15] 15 April 1978 [14] £27.7M [17] To Pakistan as Tippu Sultan

Running costs

Date Running cost What is included Citation
1981-82 £6.5 million Average annual running cost of Type 21s at average 1981–82 prices and including associated aircraft costs but excluding the costs of major refits. [18]
1985-86 £7 million The average cost of running and maintaining a type 21 frigate for one year. [19]
1987-88 £3.8 million The average annual operating costs, at financial year 1987-88 prices of a type 21 frigate. These costs include personnel, fuel, spares and so on, and administrative support services, but exclude new construction, capital equipment, and refit-repair costs. [20]


  1. 1.0 1.1 1.2 1.3 Gardiner and Chumbley 1995, p. 522.
  2. Preston 2002, p. 171.
  3. RAN Official site: HMAS Swan/ River class & Admiral Knox (RAN Director of Plans 1966-68)
  4. Couhat and Baker 1986, p. 372.
  5. Preston 2002, pp. 171, 175–176.
  6. Couhat and Baker 1986, pp. 193–194.
  7. A,Preston. The World Worst Warships. Conway Maritime (2002), p 171-75 and Sea Combat off the Falklands (1982) Profile publishing and D Brown and G Moore. Rebuilding the RN Warship Design since 1945. Seaforth (2012)
  8. Brown & Moore
  9. "Title unknown". [dead link]
  10. Moore, John Jane's Fighting Ships, 1982-83, pub Jane's Publishing Co Ltd, 1982, ISBN 0-7106-0742-3 page 554.
  11. HMS Ambuscade Facts and Figures, which contains a common internet site error and quotes the cost of Antelope as the cost of Amazon. Figures for costs of Type 21 frigates are in: Hansard: HC Deb 23 October 1989 vol 158 cc357-8W 357W Question to the Secretary of State for Defence regarding warship costs, 23 October 1989.
  12. The term used in Navy Estimates and Defence Estimates is "accepted into service". Hansard has used the term "acceptance date". Leo Marriott in his various books uses the term "completed", as does Jane's Fighting Ships. These terms all mean the same thing: the date the Navy accepts the vessel from the builder. This date is important because maintenance cycles, etc. are generally calculated from the acceptance date.
  13. "Unit cost, i.e. excluding cost of certain items (e.g. aircraft, First Outfits)." - Text from Defences Estimates
    "They do not include other costs, such as those for Government Furnished Equipment (GFE)—as they are not held centrally for each ship and could be provided only at disproportionate cost." Bob Ainsworth, Minister of State for the Armed Forces, 16 July 2008.
  14. 14.00 14.01 14.02 14.03 14.04 14.05 14.06 14.07 14.08 14.09 14.10 14.11 14.12 14.13 14.14 14.15 14.16 14.17 14.18 14.19 14.20 14.21 14.22 14.23 14.24 14.25 14.26 14.27 14.28 14.29 14.30 14.31 Lippiett, John Modern Combat Ships 5, Type 21, pub Ian Allan, 1990, ISBN 0-7110-1903-7 page 16.
  15. 15.00 15.01 15.02 15.03 15.04 15.05 15.06 15.07 15.08 15.09 15.10 15.11 15.12 15.13 Hansard: HC Deb 23 October 1989 vol 158 cc357-8W 357W Question to the Secretary of State for Defence regarding warship costs, 23 October 1989. This section is mislabelled - it is the first part of the table that is continued on Hansard: HC Deb 23 October 1989 vol 158 c360W .

  16. Hansard HC Deb 27 May 1982 vol 24 c397W Question to the Secretary of State for Defence as to the current replacement cost of an Antelope class of frigate, 27 May 1982.
    Hansard: HC Deb 23 October 1989 vol 158 cc357-8W 357W Question to the Secretary of State for Defence regarding warship costs, 23 October 1989.
    Moore, John Jane's Fighting Ships, 1982-83, pub Jane's Publishing Co Ltd, 1982, ISBN 0-7106-0742-3 page 554.
  17. Hansard: HC Deb 23 October 1989 vol 158 cc357-8W 357W Question to the Secretary of State for Defence regarding warship costs, 23 October 1989 says £27.7 million.
    Moore, John Jane's Fighting Ships, 1982-83, pub Jane's Publishing Co Ltd, 1982, ISBN 0-7106-0742-3 page 554 says £28.3 million.
  18. Hansard HC Deb 16 July 1982 vol 27 cc485-6W Question to the Secretary of State for Defence about operating costs of naval vessels, 16 July 1982.
  19. Hansard HC Deb 22 January 1987 vol 108 c730W Question to the Secretary of State for Defence about operating costs of naval vessels, 22 January 1987.
  20. Hansard HC Deb 10 March 1989 vol 148 c44W Question to the Secretary of State for Defence about operating costs of naval vessels, 10 March 1989.


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