ROTHESAY CLASS FRIGATE

Type 12I ''Rothesay'' class	RN Ensign
General Characteristics
Displacement:	2,150 tons standard / 2,560 tons full load
Displacement as modified:	2,380 tons standard / 2,800 tons full load
Length:	370 ft overall (113 m)
Beam:	41 ft (12.5 m)
Draught:	17.3 ft (5.3 m)
Propulsion:	'Y-100'' plant; 2 Babcock and Wilcox boilers, 2 English Electric steam turbines, 2 shafts, 30,000 shp
Speed:	30 knots
Range:	400 tons oil fuel, 5,200 nautical miles at 12 knots
Complement:	152, later 225, modified to 235
Armament (as built):	1 x twin 4.5in gun Mark 6 1 x 40mm Bofors gun Mark 7 2 x Limbo A/S mortar Mark 10 12 x 21-in A/S torpedo tubes (removed or never shipped)
Armament (as modified):	1 x twin 4.5in gun Mark 6 1 x Sea Cat GWS-20 SAM 2 x 20mm Oerlikon guns 1 x Limbo A/S mortar Mark 10 1 x Westland Wasp HAS.1 ''MATCH'' helicopter 2 x 8-barrel 3in Knebworth/Corvus countermeasures launchers
Electronics (as built):	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
Electronics (as modified):	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

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 was the capabilities and potential of the design that it was deemed suitable for use as a fast fleet anti-submarine warfare (A/S) escort. As such, a repeat and improved Type 12 design was prepared, known as the 'Type 12I' ('I'mproved), named after the lead ship HMS ''Rothesay''. A total of 9 vessels were constructed, with the lead ship being laid down in 1956, 2 years after the last ''Whitby''. The design was successful and popular, serving the Royal Navy well into the 1980s and serving with distinction in the Falklands war.

Contents

Design

Modification

Service

HMS Rothesay

Vessels

See also

Bibliography

Design

The Type 12I 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 A/S 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 (retrospectively 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 40mm 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 12M'.

Modification

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'' ('MA'nned 'T'orpedo 'C'arrying 'H'elicopter) 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 A/S 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 A/S mortars. To allow MATCH to be carried, all of the Type 12I 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 3in countermeasures launchers were fitted on either side of the bridge, as were a pair of World War II vintage 20mm Oerlikon guns for "policing" work (and strictly limited anti-aircraft defence).
The extensive modifications of the ''Rothesays'' brought their fighting capabilities into line with the that of the original ''Leander'' class vessels.

Service

The ''Rothesays'' served throughout the 1960s and 1970s, with ''Londonderry'' converted into a weapons and electronics trials vessel in 1975. 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 conflict 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. In addition the rest of the class were refitted for service, allowing the losses and damages suffered by the Royal Navy during the conflict to be rapidly made good. 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.

HMS Rothesay

HMS Rothesay appeared in the James Bond film ''Thunderball'' (1965) as the ship which leads the attack on the ''Disco Volante''. Rothesay was refitted between 1966 and 1968 in Rosyth and on the 6th August 1969, together with HMS ''Minerva'', landed 315 men of The Parachute Regiment on Anguilla to restore order after the islanders objected to being placed under the government of Saint Kitts. During the Falklands war (1982), ''Rothesay'' was stationed in the Caribbean. She ended her career as part of the Dartmouth Training Squadron and was paid off in 1988 and sold for scrap.

Vessels

Name	Pennant	Deck Code	Builder	Laid Down	Launched	Commissioned	Fate
''Rothesay''	F107	'RO'	Yarrow, Scotstoun	November 6 1956	December 9 1957	April 23 1960	Paid off 1988, sold for scrapping
''Londonderry''	F108	'LD'	J. Samuel White, Cowes	November 15 1956	May 20 1958	October 18 1961	Paid off 1984, sunk as target 1989
''Brighton''	F106	'BR'	Yarrow, Scotstoun	July 23 1957	October 30 1959	September 29 1961	Paid off 1981, sold for scrapping 1985
''Yarmouth''	F101	'YM'	John Brown, Clydebank	November 29th 1957	March 23rd 1959	March 26th 1960	Paid off 19845, sunk as target 1987
''Falmouth''	F113	'FM'	Swan Hunter, Wallsend	November 23rd 1957	December 15th 1959	July 25th 1961	Paid off 1984, sold for scrapping 1988
''Rhyl''	F129	'RL'	HM Dockyard, Portsmouth	January 29th 1958	April 23rd 1959	October 31st 1960	Paid off 1983, sunk as target 1985
''Lowestoft''	F103	'LT'	Alex Stephens, Govan	June 19th 1958	June 23rd 1960	September 26th 1961	Paid off 1985, sunk as target 1986
''Berwick''	F115	?	Harland & Wolff, Belfast	June 16th 1958	December 15th 1959	June 1st 1961	Paid off 1985, sunk as target 1986
''Plymouth''	F126	'PL'	HM Dockyard, Devonport	July 1st 1958	July 20th 1959	May 11th 1961	Paid off 1988, permanent display in Birkenhead

See also

★ River class destroyer escort - Australian ships based on the Type 12.

★ ''Whitby'' class frigate - the original Type 12 design.

★ ''Leander'' class frigate - the Type 12M frigate, a general purpose design following on from the success of the Type 12I

Bibliography

★ "Royal Navy Frigates 1945-1983" Leo Marriot, Ian Allan, 1983 ISBN 0-7110-1322-5