Duke Class (Type 23) Frigates, United Kingdom

In February 1996 Yarrow Shipbuilders Ltd, now BAE Systems, won a contract to build three Type 23 Duke Class frigates for the Royal Navy, which brought the total number in service with the Royal Navy to 16.

The first Type 23 was commissioned in 1989. The new batch comprises: HMS Kent which was launched in May 1998 and entered service in September 2000; HMS Portland launched in May 1999 and commissioned in May 2001; and HMS St Albans launched in May 2000 and commissioned in June 2002.

In July 2006, HMS St Albans assisted in the evacuation of UK nationals from Beirut during the Israel / Lebanon conflict, as part of the Royal Navy Operation Highbrow.

In July 2004, the UK Ministry of Defence announced that the Type 23 fleet was to be reduced to 13. Batch 1 vessels, HMS Norfolk, and Marlborough were decommissioned in 2005 and Grafton in March 2006.

In September 2005, the government of Chile signed a contract for the purchase of the frigates. The Almirante Cochrane (formerly HMS Norfolk) was handed over to Chile in November 2006, Almirante Lynch (ex-HMS Grafton) in March 2007 and Almirante Condell (ex-HMS Marlborough) in May 2008.

The Type 23 was originally designed for anti-submarine warfare (ASW), but the addition of MBDA (formerly Matra BAe Dynamics) vertical-launched Seawolf point missile defence system and the Boeing Harpoon surface-to-surface missile, has expanded its role to include anti-surface warfare (ASuW).

Type 23 command and control

The SSCS Command and Control System has been developed by BAE Systems. It is a fully distributed Ada system based on SUCCESSOR technology using Intel 80486 processors, INMOS T800 transputers and a dual fibre-optic network.

The SSCS is being upgraded to be able to integrate the new Sonar 2087 and Outfit DLH decoy system. The satellite communications system is the Astrium (formerly Matra Marconi) SCOT 1D.

SSCS weapons

The ships are armed with eight Harpoon surface-to-surface missiles in two four-cell launchers and vertical-launch Seawolf (GWS 26 Mod 1 VLS). Harpoon is a medium-range (90km) anti-ship missile using inertial and active radar guidance. VLS Seawolf is a surface-to-air missile with command to line of sight (CLOS) guidance and radar and electro-optic tracking. It has a range of 6km.

MBDA (formerly the missile division of Alenia Marconi Systems) was awarded a contract for the mid-life update of the Seawolf missile which will include upgrading the radar tracking system and addition of infrared tracking, with sensor fusion technology. The new Seawolf block 2 missile entered service in July 2005.

Improvements include a new electronic fin actuation system for improved control and extended range and a new fuse with IR/RF (infrared / radio frequency) sensors for improved performance against very low sea-skimming targets.

The frigates were originally equipped with a BAE Systems RO Defence 114mm mk8 mod 0 gun with a range of 22km against surface and 6km against airborne targets. These are being replaced with the electrically driven mk8 mod 1. In 2001, HMS Norfolk was the first ship to be fitted with the new gun.

Both mod 0 and mod 1 guns have the capability to fire the new high-explosive extended-range ammunition developed by RO Defence, which extends the surface range to 27km. HMS Richmond was the first RN vessel to receive the HE ER round in April 2004.

The fire control system for the 114mm gun is the BAE Systems Sea Archer 30 (GSA 8) electro-optical fire control system.

There are also two BAE Systems / Oerlikon 30mm guns with range of 10km against surface and 3.5km against airborne targets. These are being replaced with MSI Defence Systems DS30 mk2 automatic 30mm guns, under a contract placed in September 2005.

The DS30 mk2 comprises an upgrade mount, ATK Bushmaster II cannon and an electro-optic fire control system. HMS Somerset was the first vessel to receive the new gun in 2007 and deliveries are to complete in 2014.

The ships have four 324mm torpedo tubes carrying BAE Systems Stingray lightweight torpedoes. Stingray has depth 750m and range 11km. A contract for the upgrading of the Stingray to Mod 1 standard was awarded to BAE Systems in February 2003. The upgrade includes new digital homing, guidance and control systems. The first 100 were delivered in June 2006.

Lynx ASW helicopter

The Type 23 carries the Lynx ASW helicopter which is due to be replaced by the EH-101 Merlin HAS.1 helicopter which entered service in December 1998. The Merlin helicopter provides search-and-attack capability for ASW and surface surveillance and over-the-horizon targeting for anti-surface warfare.

Countermeasures - Sea Gnat (Outfit DLB) decoys

Countermeasures systems include four Sea Gnat (Outfit DLB) decoys and a Type 182 towed torpedo decoy. The Sea Gnats are mounted on Hunting Engineering 130mm six-barrel launchers. Type 23 frigates are being fitted with the BAE Systems Outfit DLH upgrade which will allow the launch of the Siren Mk 251 active decoy round as well as the Sea Gnat. Siren entered service with the Royal Navy in January 2004.

Thales Defence UAF-1 ESM is fitted to the first seven ships and Thales Defence's UAT(1) to the rest. Thales Defence's Scorpion jammer is also fitted.

The Duke Class is fitted with the Type 2070 towed torpedo decoy system. This is being replaced with the Ultra Electronics surface ship torpedo defence (SSTD) system. HMS Westminster was the first vessel to receive the system, followed by HMS St Albans in June 2008.

Sensors

Radar systems include: BAE Systems Type 996 (AWS-9) E/F band 3D search radar, Kelvin Hughes Type 1007 I-band navigation radar and two BAE Systems Type 911 fire control radars associated with the Seawolf missile system. Type 911 is a dual band, I-band 8GHz to 10GHz and L/M-band 40GHz to 100GHz, fully automatic radar.

The Type 996 radar is to be replaced by a new medium-range radar. In March 2007, the UK MoD issued invitations to tender for the radar. Bids have been received by BAE Systems Insyte (Artisan 3D E/F-band radar), Elta Systems (EL/M-2238 STAR E/F-band) and Thales Naval UK (SMART-S mk2 E/F-band). In August 2008, BAE Systems Insyte (with Qinetiq) ARTISAN 3D E/F-band radar was selected for the MRR and the system is planned for service entry from 2011.

At present Type 23s have Thales Underwater Systems (formerly Thomson Marconi Sonar) Type 2050 medium-range bow-mounted active / passive search and attack sonar and Ultra Electronics (formerly Dowty) Type 2031Z very low-frequency passive search towed array sonar.

However the latter is to be replaced by the Thales Underwater Systems Type 2087 low-frequency active sonar (LFAS). This is a variable-depth low-frequency transmitter and a passive, towed reception array.

The Type 2087, which entered service in February 2006, has a greater range with bistatic and intercept capability.

The system is operated from DRS Technologies OPUS2 multi-function consoles. HMS Westminster, HMS Northumberland, HMS Richmond and HMS St Albans have been fitted with the new sonar.

A number of Type 23 frigates are being fitted with the SELEX Sensors and Airborne Systems Sigma Caveo thermal imaging camera.

CODLAG propulsion

The frigates are powered by a diesel-electric and gas (CODLAG) system, which consists of two Rolls Royce Spey SM1A 34,000hp gas turbines and two Alstom 1.5MW 4,400hp electric motors. There are also four Alstom 12 RP2000CZ 1.3MW 7,000hp auxiliary diesels. Using the diesel-electric motors, the economical speed is 15kt and the range is 7,800 miles. Maximum speed is 28kt.