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Description
The Type 12 Modernised, or Rothesay-class, frigate were improved versions of the original Whitby-class and deemed structurally suitable for helicopter conversion. Of the 14 ships completed (nine for the UK, two for New Zealand and three for South Africa), three were sunk by July 1964: HMS Yarmouth from bomb damage and sabotage at Malta; HMS Plymouth from enemy action, also at Malta; and HMNZS Otago in the Persian Gulf from an incident later defined as "semi-friendly fire". The remainder were thoroughly upgraded.
Alterations included improved sensor suites, Sea Cat SAM launchers, a helicopter pad and hangar for a single Westland Wasp, and the installation of torpedo tubes and anti-ship missiles. Space limitations meant that only two Sea Lance launchers could be accommodated on the quaterdeck and the torpedo armament was limited to single tubes. Nevertheless, they provided reliable service well into the 1980s.

Specifications:
Type: Frigate
Displacement: 2,150 tons standard; 2,560 tons full load
Length: 370 ft (110 m) o/a
Beam: 41 ft (12 m)
Draught: 17.3 ft (5.3 m)
Propulsion: Y-100 plant; 2 × Babcock & Wilcox boilers, 2 English Electric steam turbines, 2 shafts
Installed power: 30,000 shp (22,000 kW)
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

Radar:
1 × Type 993 surface search/target indication
1 × Type 277Q height finding
1 × Type 974 navigation
1 × MRS.3 fire-control system (4.5" guns)
2 × Type 262 Close Range Blind Fire directors (Sea Cat)
1 × Type 1010 Cossor Mark 10 IFF

Sonar:
1 × Type 174 search
1 × Type 162 target classification
1 × Type 170 attack

Armament:
1 × twin 4.5in gun Mark 6
2 × GWS-21 Sea Cat SAM launchers
2 × Sea Lance anti-ship missile box launchers
2 × 20mm Oerlikon cannon
1 × Limbo anti-submarine mortar Mark 10
2 × single 21-in anti-submarine torpedo tubes

Aircraft carried:
1 × Westland Wasp helicopter

* * *

You can see the rest of the stuff in this AU here: Timeline 27-10-1962

Description
The Type 12 Modernised, or Rothesay-class, frigate were improved versions of the original Whitby-class and deemed structurally suitable for helicopter conversion. Of the 14 ships completed (nine for the UK, two for New Zealand and three for South Africa), three were sunk by July 1964: HMS Yarmouth from bomb damage and sabotage at Malta; HMS Plymouth from enemy action, also at Malta; and HMNZS Otago in the Persian Gulf from an incident later defined as "semi-friendly fire". The remainder were thoroughly upgraded.
Alterations included improved sensor suites, Sea Cat SAM launchers, a helicopter pad and hangar for a single Westland Wasp, and the installation of torpedo tubes and anti-ship missiles. Space limitations meant that only two Sea Lance launchers could be accommodated on the quaterdeck and the torpedo armament was limited to single tubes. Nevertheless, they provided reliable service well into the 1980s.

Specifications:
Type: Frigate
Displacement: 2,150 tons standard; 2,560 tons full load
Length: 370 ft (110 m) o/a
Beam: 41 ft (12 m)
Draught: 17.3 ft (5.3 m)
Propulsion: Y-100 plant; 2 × Babcock & Wilcox boilers, 2 English Electric steam turbines, 2 shafts
Installed power: 30,000 shp (22,000 kW)
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

Radar:
1 × Type 993 surface search/target indication
1 × Type 277Q height finding
1 × Type 974 navigation
1 × MRS.3 fire-control system (4.5" guns)
2 × Type 262 Close Range Blind Fire directors (Sea Cat)
1 × Type 1010 Cossor Mark 10 IFF

Sonar:
1 × Type 174 search
1 × Type 162 target classification
1 × Type 170 attack

Armament:
1 × twin 4.5in gun Mark 6
2 × GWS-21 Sea Cat SAM launchers
2 × Sea Lance anti-ship missile box launchers
2 × 20mm Oerlikon cannon
1 × Limbo anti-submarine mortar Mark 10
2 × single 21-in anti-submarine torpedo tubes

Aircraft carried:
1 × Westland Wasp helicopter

* * *

You can see the rest of the stuff in this AU here: Timeline 27-10-1962