Rothesay-class frigate

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 the 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 called 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.

Rothesay-class frigate
Class Ship
Type Frigate
Manufacturer John Brown & Company
Origin United Kingdom - UK (Great Britain)
Country Name Origin Year
United Kingdom - UK (Great Britain) 1959
Country Name Operational Year Retirement Year
South Africa 1962 1985 View
United Kingdom - UK (Great Britain) 1960 1988 View
New Zealand 1960 1983 View
ManufacturerName Production From Production To Quantity
John Brown & Company View
Yarrow Shipbuilders View
J. Samuel White View
HMNB Portsmouth View
English Electric View
HMNB Devonport View
Harland & Wolff Heavy Industries View
Swan Hunter View
Wallsend Slipway & Engineering Company View
Parsons Marine Steam Turbine Company View
Alexander Stephen and Sons View
Cammell Laird View
John I. Thornycroft & Company View

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.

Ships in Class

Pennant Name Builder Ordered Laid Down Launched Accepted into service Commissioned Estimated building cost Fate
Royal Navy
F101 Yarmouth (a) & (b) John Brown and Co Ltd, Clydebank.
29 November 1957 23 March 1959 March 1960 26 March 1960 £3,505,000 Paid off April 1986, sunk as target July 1987.
F107 Rothesay (a) & (b) Yarrow & Co Ltd, Glasgow.
6 November 1956  9 December 1957 April 1960 23 April 1960 £3,715,000 Paid off 30 March 1988,[8]sold for scrapping 1988.
F108 Londonderry (a) & (b) JS White & Co Ltd,Cowes, Isle of Wight.
15 November 1956 20 May 1958 July 1960 18 October 1961 £3,570,000 Paid off 29 March 1984,[8]sunk as target 15 June 1989.
F129 Rhyl (a) HM Dockyard, Portsmouth
(b) English Electric Co Ltd, Rugby.

29 January 1958 23 April 1959 November 1960 31 October 1960 £3,625,000 Paid off 1982, sunk as target September 1985.
F126 Plymouth (a) HM Dockyard, Devonport
(b) English Electric Co Ltd, Rugby.

1 July 1958 20 July 1959 June 1961 11 May 1961 £3,510,000 Paid off 26 April 1988,[8]transferred to Warship Preservation Trust April 1989. Scrapped in Aliaga, Turkey, October 2014.
F115 Berwick (a) & (b) Harland & Wolff Ltd, Belfast.
16 June 1958 15 December 1959 June 1961 1 June 1961 £3,650,000 Paid off 1985, sunk as target September 1986.
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.

23 November 1957 15 December 1959 July 1961 25 July 1961 £3,805,000 Paid off July 1980, to standby. Reactivated 1982 for South Atlantic patrols. Struck 1984. Sold for scrapping 1989.
F103 Lowestoft (a) & (b) Alex Stephens and Sons Ltd, Linthouse, Glasgow.
9 June 1958 23 June 1960 October 1961 26 September 1961 £3,510,000 Paid off 1985, sunk as target 16 June 1986.
F106 Brighton (a) & (b) Yarrow & Co Ltd, Glasgow.
23 July 1957 30 October 1959 October 1961 28 September 1961 £3,600,000[10] Paid off 1981(?), sold for scrapping 16 September 1985.

Weymouth (a) Harland & Wolff Ltd, Belfast.
10 April 1959

Cancelled 1960, and completed as the Leander-class frigate Leander.

Fowey (a) Cammell Laird and Co (Shipbuilders and Engineers) Ltd,Birkenhead.
19 October 1950

Cancelled 1960, and completed as the Leander-class frigate Ajax.

Hastings (i) (a) JI Thornycroft Ltd, Southampton. February 1956

To New Zealand February 1957 (see HMNZS Otagobelow).

Hastings (i) (a) Yarrow & Co Ltd, Glasgow.
2 December 1959

Cancelled 1960, and completed as the Leander-class frigate Dido.
Royal New Zealand Navy
F111 HMNZSOtago
(a) JI Thornycroft Ltd, Southampton. February 1956 (for RN)
February 1957 (for RNZN)
5 September 1957 11 December 1958
22 June 1960
Stricken 1983.
F148 HMNZSTaranaki (a) JS White & Co Ltd, Cowes, Isle of Wight.
27 June 1958 19 August 1959
28 March 1961
Stricken 1982, sold.
South African Navy
F150 SASPresident Kruger (a) Yarrow & Co Ltd, Glasgow.
6 April 1960 21 October 1960
1 October 1962
Sunk on 18 February 1982, after a collision at sea with the replenishment ship SASTafelberg.
F147 SASPresident Steyn (a) Alex Stephen & Sons Ltd, Linthouse, Glasgow.
20 May 1960 [12] 23 November 1961
26 April 1963
Paid off 1984. Sold for breaking up 1990.
F145 SASPresident Pretorius (a) Yarrow & Co Ltd, Glasgow.
21 November 1960 28 September 1962
4 March 1964
Paid off 1985, sold for breaking up 1990.

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. Plymouth, Yarmouth, and 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. Plymouth and Yarmouth were despatched with the task force, with Plymouth 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. Plymouth?'?s Wasp helicopter guided an AS-12 missile onto the elderly surface running submarine ARA Santa Fe, but only after it had been prevented from diving by depth charges and torpedo hits from a destroyer HMS Antrim and from a Wessex and a Lynx helicopter. On 1 May Yarmouth and the modern Type 22 HMS Brilliant, detected submarine ARA San 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. Berwick and 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 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.

Class overview
Operators:  Royal Navy
 Royal New Zealand Navy
 South African Navy
Preceded by: Type 12 Whitby
Succeeded by: Type 12I Leander
Completed: 21
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 Electricsteam 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

End notes