Rothesay-class frigate

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HMS Plymouth underway.jpg
Class overview
Operators:  Royal Navy
 Royal New Zealand Navy
 South African Navy
Preceded by: Type 12 Whitby
Succeeded by: Type 12I Leander
Completed: 21[1]
Lost: 5 (as targets) + 1 (accident)
Retired: 4
Preserved: 1
General characteristics as built
Displacement: 2,150 tons / 2,560 tons full load
Length: 370 ft o/a (113 m)
Beam: 41 ft (12 m)
Draught: 17.3 ft (5.3 m)
Propulsion: Y-100 plant; 2 x Babcock and Wilcox boilers, 2 English Electric steam turbines, 30,000 shp on 2 shafts
Speed: 30 knots (56 km/h)
Range: 400 tons oil fuel; 5,200 nautical miles (9,630 km) at 12 knots (22 km/h)
Complement: 152
Sensors and
processing systems:
Radar Type 293Q target indication

Radar Type 277Q height finding
Radar Type 275 fire control on director Mark 6M
Radar Type 974 navigation
Type 1010 Cossor Mark 10 IFF
Sonar Type 174 search
Sonar Type 162 target classification

Sonar Type 170 attack
Armament: 1 x twin 4.5in gun Mark 6

1 x 40 mm Bofors gun Mark 7
2 x Limbo anti-submarine mortar Mark 10

12 x 21-in anti-submarine torpedo tubes (removed or never shipped)
General characteristics (as modified)
Displacement: 2,380 tons / 2,800 tons full load
Complement: 235
Sensors and
processing systems:
Radar Type 993 target indication

Radar Type 903 fire control on director MRS3
Radar Type 978 navigation
Type 1010 Cossor Mark 10 IFF
Sonar Type 177 search
Sonar Type 162 target classification

Sonar Type 170 attack
Armament: 1 x twin 4.5in gun Mark 6

1 x Sea Cat GWS-20 SAM
2 x 20 mm Oerlikon guns
1 x Limbo anti-submarine mortar Mark 10

2 x 8-barrel 3in Knebworth/Corvus countermeasures launchers
Aircraft carried: 1 x Westland Wasp HAS.1 MATCH helicopter
Notes: Other characteristics as per above

The Rothesay class, or Type 12M frigates were a class of frigates serving with the Royal Navy, South African Navy (where they were called President-class frigates) and the New Zealand Navy.

The original Type 12 frigates, the Whitby class, were designed as first-rate ocean-going convoy escorts in light of experience gained during World War II. However, such were the capabilities and potential of the design that it was deemed suitable for use as a fast fleet anti-submarine warfare escort. As such, a repeat and improved Type 12 design was prepared, known as the Type 12M (M for "modified"), and known as the Rothesay class after the lead ship. A total of twelve vessels were constructed, with the lead ship being laid down in 1956, two years after the last Whitby. The design was successful and popular, serving the Royal Navy and South African Navy well into the 1980s and serving with distinction in the Falklands war.

Design[edit]

The Type 12M retained the excellent hull design of the Type 12, that allowed high cruising speed to be maintained in heavy seas, critical to the success of anti-submarine warfare in the era of the threat of the high-speed Soviet submarine. Armament and the propulsion plant remained largely unchanged. The main external differences were an enlarged raked and streamlined funnel (retroactively fitted to the Whitbys) and a modified after deckhouse, enlarged to carry the Sea Cat anti-aircraft missile launcher and its associated GWS-20 director and handling rooms as it became available. This weapon was not available originally, therefore a single 40 mm Bofors Mark 7 gun was shipped in lieu. The arrangement of the torpedo tubes was also altered in the new design, with 4 fixed tubes firing aft at 45° on each beam, in front of a trainable twin mounting; the reverse of the arrangement on the Whitbys. A suitable weapon was never developed for these tubes, so they remained unused, or were never fitted. Internally, electrical generation capacity was increased to handle the increasing demands created by improved ships electronics. Accommodation standards were also improved, with partial bunking and air conditioning. Such was the success of the Rothesay design that it was elaborated into the excellent general purpose Leander-class frigate, the Type 12I.

Modification[edit]

Rothesay before her Seacat/helicopter upgrade - note 40 mm gun in stern

Increasing submarine performance in the 1960s demanded detection and engagement of targets at a greater distance from the fleet. Detection was improved with new sonar designs such as the Type 177 search and Type 199 Variable depth. To attack targets at a greater range, the Royal Navy adopted the MATCH (Medium-range Anti-submarine Torpedo Carrying Helicopter) system. MATCH was essentially the Westland Wasp HAS.1, a lightweight navalised helicopter small enough to operate from a small hangar and flight deck that could be fitted to contemporary frigate designs yet large enough to carry a pair of anti-submarine homing torpedoes (US Mark 44 or 46 types), allowing engagement of underwater targets at some distance from the parent vessel, outside the range of the shipboard Limbo anti-submarine mortars. To allow MATCH to be carried, all of the Type 12M class were modified and modernised, beginning with Rothesay from 1966 and finishing in 1972.

The after superstructure was removed, along with the foremost Limbo mortar, with the well being plated over to create a small flight deck. A small hangar was constructed in front of this, on top of which the GWS-20 Sea Cat missile and director was (finally) shipped. The mainmast was replaced by am enclosed design, carrying the Type 1010 IFF antennas, with the funnel height was increased to carry the hot exhaust gasses over the taller superstructure. The electronics fit was also upgraded from the World War II era sets fitted in the Whitbys. A large, enclosed foremast replaced the short lattice, carrying the distinctive "half cheese" antennas associated with the Type 993 target indicator. The Mark 6M director was replaced with the MRS3 system carrying radar Type 903, allowing the removal of the Type 277Q height finder. Additionally, Knebworth/Corvus 3-inch countermeasures launchers were fitted on either side of the bridge, as were a pair of World War II vintage 20 mm Oerlikon guns for "policing" work (and strictly limited anti-aircraft defence).

The extensive modifications of the Rothesays brought their armament and anti submarine capabilities into line with the that of the original Leander-class vessels. However the last 4 Leanders had Doppler full spectrum 184 sonar which gave a clearer faster, read sonar, and all the Leander's originally had long range air warning and AD capabilities and communication decks, while the Type 12 Rothesays remained specialised anti submarine frigates to perform better at that single purpose. In 1978, Rothesay, went into refit for 2 years at a cost of 33.4 million pounds [2] Yarmouth and Plymouth completed similar refits in 1981, which included fitting 994 short range warning radar and target indicator essentially( Plessy AWS1) in the old antenna, giving faster screen data in the Rothesay's operations room. This recent refit and marginally better radar resulted in their debatable despatch for use in the Falklands War.[3] In the immediate aftermath HMS Berwick and Falmouth twice deployed south for post-war patrols in 1982-3, probably ending plans to refit them as towed array frigates, as well as sister ship HMS Rhyl which suffered mechanical failure when ordered south, and HMS Brighton which was scrapped following the Nott Defence Review and never transferred to the standby force

Service[edit]

The Rothesays served throughout the 1960s and 1970s, with Londonderry converted into a weapons and electronics trials vessel in 1975. The successful performance of the Rothesays, and the ability they showed for sustained operation in rough North Atlantic sea conditions during the 1976 Cod War, combined with the intensification of the Cold War and a more generous naval budget in the late 1970s provided by the new Prime Minister the former RN Clerk James Callaghan led to a provisional decision to retain the Rothesays through the 1980s with a second long refit. HMS Plymouth, HMS Yarmouth, and HMS Rothesay were given full 2-year refits in 1978-81 with some significant updates of radar. At the beginning of 1982 many of the class had been relegated to the Standby Squadron, likely to be disposed of following the 1981 defence review, with their sister ships likely to follow suit. However, the outbreak of the Falklands War reprieved the class, and Plymouth and Yarmouth were despatched with the task force, with Plymouth in particular playing one of the most active roles of any ship. While the class proved highly seaworthy in the rough South Atlantic, particularly in the winter patrols that followed, the initial favourable assessment of their performance in the war has been revised. It is questionable whether Seacat achieved a single kill, although both Yarmouth and Plymouth claim, single shared hits on Skyhawks. HMS Plymouth's Wasp helicopter guided an AS-12 missile onto the elderly surface running submarine Santa Fe, but only after it had been prevented from diving by depth charges and torpedo hits from HMS Antrim, Wessex and a Lynx. On 1 May HMS Yarmouth and the modern Type 22 Brilliant, detected the A.R.A 209 submarine St Luis, which fired at least one German anti ship ST 4 torpedo at them, but they failed to sink the submarine in 20 hours of mortar, torpedo and depth charge attacks[4] In the following weeks, the limitations of the Rothesay's lack of modern sonar or link 10 data link were exposed, although Yarmouth saw the second Exocet fired and may have successfully decoyed it with chaff, if fired. Other than Brighton the rest of the class were refitted for post war service, allowing the losses and damages suffered by the Royal Navy during the conflict to be rapidly made good. HMS Berwick and HMS Falmouth had been retained in a state of high readiness in the standby squadron, in the expectation they would be given a further long refit, possibly as yowed array frigates. Their sister HMS Lowestoft had been tested in this role. Berwick in particular still proved useful after its short refit, giving another 3 years' operational service, until mid 1985. The class paid off throughout the 1980s, with Rothesay finally paying off in 1988. The demise of the class also saw the withdrawal of the Wasp helicopter, the Leanders having been upgraded to carry the Westland Lynx.

New Zealand ships[edit]

The New Zealand Navy ordered two Type 12 ships in February 1957. Hastings was transferred as the Otago while under construction, and Taranaki was ordered directly from the builders.They introduced bunk rather than traditional hammock bedding and rather different messing arrangements from the RN Type 12s. The ships were fitted with Seacat missiles by 1964. Unlike the RN Rothesays the Otago and Taranaki actually were armed with the Mk 20 heavyweight a/s torpedoes but abandoned them in the mid 1960s when it was clear the RN would only develop the weapons for submarines. The official reason for the RNZN abandoning heavweight torpedoes was the Mk 20 was, too slow at '24' knots. Mk 32 tubes to fire Mk 44/46 12.75-inch US lightweight torpedoes, supplied to NZ about 1971 as surplus from life expired, early 1960's USN FRAM destroyers and fitted to all RNZN frigates in 1971 as a matter of policy to replace the Limbo mortars, which were removed at major refits in July 1974. A minority of the RNZN officers and ratings opposed the change, on the grounds the mortars were more effective for cold war warning.[5] The New Zealanders considered modernising Taranaki with gas turbines but retired the ships after 1981 when two surplus Leander-class frigates were offered for sale by the British.

South African ships (President class)[edit]

Three Type 12 frigates were ordered as part of the Simonstown Naval Agreement. They were identical to the Royal Navy vessels when built but were altered during refits. The three ships were named after presidents of the Boer republics:

The modernisation involved installing a hangar and flight deck for a Westland Wasp helicopter, removing the Limbo mortar to form the flight deck, replacing the air search radar and fire control system and adding two triple 12.75-inch (324 mm) anti-submarine torpedo tubes.

The ships proved difficult to maintain due to the arms embargo and President Steyn was decommissioned in 1980 to provide spare parts.

Construction programme[edit]

Pennant Name Builder Ordered Laid Down Launched Accepted into service[Note 1] Commissioned Estimated building cost[Note 2] Fate
Royal Navy
F101 Yarmouth (a) & (b) John Brown and Co Ltd, Clydebank.[6] 29 November 1957 [7] 23 March 1959 [7] March 1960 [6] 26 March 1960 [7] £3,505,000 [6] Paid off April 1986, sunk as target July 1987.[7][8]
F107 Rothesay (a) & (b) Yarrow & Co Ltd, Glasgow.[9] 6 November 1956 [7] 9 December 1957 [7] April 1960 [9] 23 April 1960 [7] £3,715,000 [9] Paid off 30 March 1988,[8] sold for scrapping 1988.[7]
F108 Londonderry (a) & (b) JS White & Co Ltd, Cowes, Isle of Wight.[9] 15 November 1956 [7] 20 May 1958 [7] July 1960 [9] 18 October 1961 [7] £3,570,000 [9] Paid off 29 March 1984,[8] sunk as target 15 June 1989.[7][8]
F129 Rhyl (a) HM Dockyard, Portsmouth
(b) English Electric Co Ltd, Rugby.[9]
29 January 1958 [7] 23 April 1959 [7] November 1960 [9] 31 October 1960 [7] £3,625,000 [9] Paid off 1982, sunk as target September 1985.[7][8]
F126 Plymouth (a) HM Dockyard, Devonport
(b) English Electric Co Ltd, Rugby.[10]
1 July 1958 [7] 20 July 1959 [7] June 1961 [10] 11 May 1961 [7] £3,510,000 [10] Paid off 26 April 1988,[8] transferred to Warship Preservation Trust April 1989.[7] Scrapped in Aliaga, Turkey, October 2014.
F115 Berwick (a) & (b) Harland & Wolff Ltd, Belfast.[10] 16 June 1958 [7] 15 December 1959 [7] June 1961 [10] 1 June 1961 [7] £3,650,000 [10] Paid off 1985,[8] sunk as target September 1986.[7][8]
F113 Falmouth (a) Swan, Hunter & Wigham Richardson Ltd, Wallsend-on-Tyne
(b) The Wallsend Slipway & Engineering Co Ltd, Wallsend-on-Tyne
(b) Parsons Marine Turbines Co Ltd, Wallsend-on-Tyne.[10]
23 November 1957 [7] 15 December 1959 [7] July 1961 [10] 25 July 1961 [7] £3,805,000 [10] Paid off July 1980,[8] to standby. Reactivated 1982 for South Atlantic patrols. Struck 1984. Sold for scrapping 1989.[7][8]
F103 Lowestoft (a) & (b) Alex Stephens and Sons Ltd, Linthouse, Glasgow.[10] 9 June 1958 [7] 23 June 1960 [7] October 1961 [10] 26 September 1961 [7] £3,510,000 [10] Paid off 1985, sunk as target 16 June 1986.[7][8]
F106 Brighton (a) & (b) Yarrow & Co Ltd, Glasgow.[10] 23 July 1957 [7] 30 October 1959 [7] October 1961 [10] 28 September 1961 [7] £3,600,000 [10] Paid off 1981(?), sold for scrapping 16 September 1985.[7][8]
Weymouth (a) Harland & Wolff Ltd, Belfast.[7] 10 April 1959 [7] Cancelled 1960, and completed as the Leander-class frigate Leander.[7]
Fowey (a) Cammell Laird and Co (Shipbuilders and Engineers) Ltd, Birkenhead.[7] 19 October 1950 [7] Cancelled 1960, and completed as the Leander-class frigate Ajax.[7]
Hastings (i) (a) JI Thornycroft Ltd, Southampton.[7] February 1956 [7] To New Zealand February 1957 (see HMNZS Otago below).[7]
Hastings (i) (a) Yarrow & Co Ltd, Glasgow.[7] 2 December 1959 [7] Cancelled 1960, and completed as the Leander-class frigate Dido.[7]
Royal New Zealand Navy
F111 HMNZS Otago (ex Hastings) (a) JI Thornycroft Ltd, Southampton.[11] February 1956 (for RN)
February 1957 (for RNZN) [7][11]
5 September 1957 [11] 11 December 1958 [11] 22 June 1960 [11] Stricken 1983.
F148 HMNZS Taranaki (a) JS White & Co Ltd, Cowes, Isle of Wight.[11] 27 June 1958 [11] 19 August 1959 [11] 28 March 1961 [11] Stricken 1982,[8] sold.[11]
South African Navy
F150 SAS President Kruger (a) Yarrow & Co Ltd, Glasgow.[12] 6 April 1960 [12] 21 October 1960 [12] 1 October 1962 [12] Sunk on 18 February 1982, after a collision at sea with the replenishment ship SAS Tafelberg.[12]
F147 SAS President Steyn (a) Alex Stephen & Sons Ltd, Linthouse, Glasgow.[12] 20 May 1960 [12] 23 November 1961 [12] 26 April 1963 [12] Paid off 1984. Sold for breaking up 1990.[8][12]
F145 SAS President Pretorius (a) Yarrow & Co Ltd, Glasgow.[12] 21 November 1960 [12] 28 September 1962 [12] 4 March 1964 [12] Paid off 1985, sold for breaking up 1990.[8][12]

Deck codes after midlife refits[edit]

Name Pennant Deck Code
Rothesay F107 RO
Londonderry F108 LD
Brighton F106 BR
Yarmouth F101 YM
Falmouth F113 FM
Rhyl F129 RL
Lowestoft F103 LT
Berwick F115 BK
Plymouth F126 PL

See also[edit]

External links[edit]

Notes[edit]

  1. ^ 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.
  2. ^ "Unit cost, i.e. excluding cost of certain items (e.g. aircraft, First Outfits)."
    Text from Defences Estimates

References[edit]

  1. ^ HT Lenton (1967). Warships of the British & Commonwealth Navies. Allan. 
  2. ^ UK Hansard 2/7/81 ; cf table-( Rothesay/ Leander refit cost) R .J.Alrich Intelligence, Defence and Dilomacy. British Policy in the Post war World Routledge( 2013)p 112.
  3. ^ . Admiral Sandy Woodward. One Hundred Days. Memoirs of the Falklands Battle Group.(3rd ed)Harper (2012) London.
  4. ^ Lt Cdr S. R Harper.USN. Submarine Operations in the Falklands War. Naval War College, R.I.1994. USA
  5. ^ Lt Cmdr Jackson & Ratings. Vist of HMNZS Otago to Timaru 1974 and (2) Lt Cmdr Jackson. TBHS vist 1974 and (3)Lt Cmdr Dick Ryan. Otago University. Talk & discussion 1984).
  6. ^ a b c Navy Estimates, 1960-61, pages 226-7, List and particulars of new ships which have been accepted or are expected to be accepted into HM service during the Financial Year ended 31 March 1960
  7. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw Gardiner, Robert Conway's All the World's Fighting Ships 1947-1995, pub Conway Maritime Press, 1995, ISBN 0-85177-605-1 page 519.
  8. ^ a b c d e f g h i j k l m n o Friedman, Norman British Destroyers and Frigates, the Second World War and After, pub Seaforth, 2006, ISBN 978-1-84832-015-4 page 337.
  9. ^ a b c d e f g h i Navy Estimates, 1961-62, pages 222-3, List and particulars of new ships which have been accepted or are expected to be accepted into HM service during the Financial Year ended 31 March 1961
  10. ^ a b c d e f g h i j k l m n o Navy Estimates, 1962-63, pages 218-9, List and particulars of new ships which have been accepted or are expected to be accepted into HM service during the Financial Year ended 31 March 1962
  11. ^ a b c d e f g h i j Gardiner, Robert Conway's All the World's Fighting Ships 1947-1995, pub Conway Maritime Press, 1995, ISBN 0-85177-605-1 page 284.
  12. ^ a b c d e f g h i j k l m n o Gardiner, Robert Conway's All the World's Fighting Ships 1947-1995, pub Conway Maritime Press, 1995, ISBN 0-85177-605-1 page 334.