Missing image HMS_Andromeda_(Leander-class_frigate).jpg HMS Andromeda HMS Andromeda
Type 12 (Leander)-class
General Characteristics
Displacement:	2860 tons full load (Batch 1 and 2)/3000 tons full load (Batch 3)
Length:	372 ft (113 m)
Beam:	41 ft (12.5 m) Batch 1 and 2, 43 ft (13.1 m) Batch 3
Draught:	18 ft (5.5 m)
Propulsion:	2 shafts, 2 steam turbines, 2 boilers, 25,000 shp (19 MW)
Speed:	28 knots (52 km/h)
Range:	4500 nautical miles (8,000 km) at 12 knots (22 km/h)
Complement:	257
Armament:	2 twin mount x 4.5 in (114 mm) gun (later removed on five Batch 3. Removed in all Batch 1 and 2 ships) 2 x 40 mm gun (Later removed from Batch 1 and 2 ships. Also removed from five Batch 3 ships) 2 x 20 mm gun (Batch 1 and 2. One x 20 mm gun later added to Batch 3 ships) SeaCat anti-air missile launcher (Batch 1 and 2. Removed from five Batch 3s) SeaWolf anti-air missile launcher (Five Batch 3 ships) Exocet anti-ship missile launcher (Batch 2 and five Batch 3s) Mk 10 Limbo mortar (Batch 1. Later removed from all Batch 2s and five Batch 3s) Ikara ASW missile launcher (Batch 1)
Aircraft:	1 Westland Wasp (Batch 2 and 3 were later refitted to operate Westland Lynx)

The Type 12 (Leander)-class were a twenty-six class of frigates, arguably the most successful and popular frigates in the Royal Navy's history. The class were built in three batches, each batch having distinct roles.

The first batch were general purpose as an alternative to the far more expensive single role classes such as the Rothesay-class and Whitby-class frigates. They had the Y100 engine design which would be replaced by the subsequent two batches, as-well as much better accommodation for the crew, including air conditioning. They also were designed from the start to operate one helicopter, a feature rather rare during that time.

They were originally armed with one twin mount 4.5 in (114 mm) gun, but this was later removed in favour of the Australian designed Ikara anti-submarine warfare (ASW) rocket launcher in response to the perceived threat of Soviet submarines, effectively turning the batch one vessels into ASW frigates. The SeaCat missile was also installed, replacing the 40 mm guns.

The Batch Two ships were designed for the specialised anti-submarine warfare (ASW) role and were only slightly revised to the batch ones, in that they had a different engine design, known as the Y136. The one twin mount 4.5-in gun was later replaced with the Exocet anti-ship missile launcher giving them a potent anti-ship capability. The SeaCat missile and 6 torpedo tubes were also added. The ASW mortar was also removed to allow the helicopter deck to be extended to enable the class to operate the larger, and more capable, Westland Lynx.

The Batch Three ships were also revised, having their beam increased in size from 41 ft to 43 ft to give more internal space, as-well as to improve stability, which also allowed the Batch Threes to be more receptive to modernisation.

The third batch had a different engine design, known as the Y160. On five ships of the batch, the one twin mount 4.5 in (114 mm) gun, SeaCat missile launcher, 40 mm guns, and Limbo mortar were all removed in favour of three 20mm Oerlikon guns, and SeaWolf and Exocet missile launchers. The 20 mm Oerlikon gun was added to all Batch Three ships.

The Leanders were successfully exported under license to Australia, India and the Netherlands. Ex-RN ships were sold to Chile, Ecuador, India Pakistan and New Zealand. The ships performed excellently in RN service, but they were ageing and manpower intensive, at a time when the RN were suffering yet another manpower crisis, and with defence cuts, all Leanders in RN service were decommissioned by the early 1990s. Some Leanders remain in-service with foreign navies. On the 27th March 2004, HMS Scylla was sunk as an artificial reef off Cornwall. It had been ten years since her decommissioning in 1994.

Leander class variants