Type 23 frigate

The Type 23 frigate or Duke class is a class of frigates built for the United Kingdom's Royal Navy. The ships are named after British Dukes, thus leading to the class being commonly known as the Duke class. The first Type 23, HMS Norfolk, was commissioned in 1989, and the sixteenth, HMS St Albans was commissioned in June 2002. They form the core of the Royal Navy's destroyer and frigate fleet and serve alongside the Type 45 destroyers. They were designed for anti-submarine warfare, but have seen a range of duties. Eight Type 23 frigates remain in service with the Royal Navy, with three vessels having been sold to the Chilean Navy and five being retired since 2021.^{[citation needed]}

The Royal Navy's Type 23 frigates will be replaced by the Type 26 Global Combat Ship and the Type 31 frigate. As of 2021^[update] it is anticipated that HMS St Albans will be the last to retire from the Royal Navy, in 2035.

When first conceived in the late 1970s, the Type 23 was intended to be a light anti-submarine frigate with a towed array sonar to counter Soviet nuclear submarines operating in the North Atlantic. The Type 23 would be replacing the Leander-class frigates (which had entered service in the 1960s) and the Type 21 frigate (a general purpose design that had recently entered service) as the backbone of the Royal Navy's surface ship anti-submarine force. The procurement of the class was announced in the 1981 Defence White Paper as "simpler and cheaper than the Type 22 [with] its characteristics... framed with an eye to the export market as well as Royal Navy needs."

The ship was designed by the Royal Corps of Naval Constructors, in close partnership with the prime contractor, Yarrow Shipbuilders. No anti-air warfare system was planned, however the lessons learned during the Falklands War led to the introduction of the vertically launched Sea Wolf missile; In June 1984 BAe Dynamics was awarded a development contract for the missile system. Unlike conventional Sea Wolf, the missile is boosted vertically until it clears the ship's superstructure, and then turns to fly directly to the target. Consequently, the ship's structure does not impose no-fire directions that would delay or inhibit missile firing in a conventionally launched system. With the addition of Harpoon surface-to-surface missiles and a medium calibre gun for naval gunfire support, the Type 23 had evolved into a more complex and balanced vessel optimised for general warfare, which introduced a host of new technologies and concepts to the Royal Navy. These included extensive radar cross-section reduction design measures, automation to substantially reduce crew size, a combined diesel-electric and gas (CODLAG) propulsion system providing very quiet running for anti-submarine operations and a large range.

In December 1986 the procurement of a Ferranti command and control system was cancelled as the specification was deemed to be insufficient to meet the demands of a modern warship, particularly the processing demands of the towed sonar array. Dowty-Sema won a contract for a replacement command and control system in August 1989, however, the delay meant early Type 23s entered service without the capability to use the Sea Wolf missile system in combat.

It was reported in 1998 to the House of Commons that: "Type 23 frigates achieved approximately 85–89 percent average availability for operational service in [the previous] five years with the exception of 1996 when the figure dropped to just over 80 per cent due to a number of ships experiencing a particular defect. This discounts time spent in planned maintenance."

Unlike the Type 45 destroyer, the Type 23 frigate does not have the capability to act as a flagship.

Prior to the Falklands War the cost of the Type 23 frigates was estimated at £75 million each (September 1980 prices) Changes following the experiences in the Falklands, including improved damage control and fire precautions, led to an increased cost estimated at £110 million (1984–85 prices) By 2001, the Ministry of Defence said the cost of HMS Norfolk was £135.449 million and the remaining ships would have a final cost between £60 million and £96 million each. The Ministry of Defence said in 1998 that the Merlin ASW helicopter was costing them £97M each (this was for an order for 44 airframes), and that this was 57% of the cost of Type 23. From this it can be calculated that the cost of Type 23 was £170.1M each. The Government's declared policy for construction contracts for Type 23 was "...competition, the aim being to secure best value for money for the defence budget." while maintaining "sufficient warship-building capacity to meet likely future defence requirements and a competitive base"