Type 23 frigates were built for the for UK Royal Navy. Credit: Royal Navy.
The maximum speed of the Type 23 vessel is 28k. Credit: Royal Navy.
The first Type 23 frigate was commissioned in 1990. Credit: Royal Navy.
The satellite communications are carried out through the Astrium SCOT 1D. Credit: Ultra Electronics.

Type 23 Duke class frigates are multi-role warships built by Swan Hunter and BAE Systems for the UK’s Royal Navy. The frigates are the core of the Royal Navy’s front-line fleet designed to safeguard Britain’s important maritime trade routes.

Type 23 frigates were originally designed for anti-submarine warfare (ASW), but the addition of the 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).

A total of 16 Type 23 vessels were built to date and the first of these was commissioned in 1990. The Type 23 Duke class frigates include HMS Norfolk (F230), HMS Argyle (F231), HMS Lancaster (F229), HMS Marlborough (F233), HMS Iron Duke (F234), HMS Monmouth (F235), HMS Montrose (F236), HMS Westminister (F237), HMS Northumberland (F238), HMS Richmond (F239), HMS Somerset (F82), HMS Grafton (F80), HMS Sutherland (F81), HMS Kent (F78), HMS Portland (F79), and HMS St Albans (F83).

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

All three were sold to the Chilean Navy and delivered over 2007-2008. Grafton was renamed Almirante Lynch (FF-07), Marlborough to Almirante Condell (FF-06), and Norfolk to Almirante Cochrane (FF-05).

The base port of eight Type 23 frigates was changed to Plymouth and the remaining five will be based in Portsmouth.

Type 23 Duke Class frigate deployments and test firings

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 2006.

In late July 2011, British Royal Navy frigate Type 23 Duke-class HMS Sutherland conducted a boarding operation in international waters close to Libya. This operation was to prevent the flow of illegal weapons into the hands of pro-Gaddafi forces to protect Libyan civilians.

The British Royal Navy conducted test firing of the Sea Ceptor air defence missile system from HMS Argyll and HMS Westminster in December 2017. It was followed by the test firing of the Martlet missile, which was fitted on an MSI Defence 30mm remote weapon station from HMS Sutherland in July 2019.

Type 23 command and control

The surface ship command system (SSCS) was 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 has been upgraded 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 a command to line of sight (CLOS) guidance and radar and electro-optic tracking. It has a range of 6km.

“The Type 23 frigates were originally designed for anti-submarine warfare.”

The missile division of Alenia Marconi Systems (now part of MBDA) 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 the surface and 6km against airborne targets. These have been 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 a range of 10km against the surface and 3.5km against airborne targets. These have been replaced with MSI Defence Systems DS30 mk2 automatic 30mm guns as part of a contract placed in September 2005.

The DS30 mk2 comprises an upgraded 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.

The ships have four 324mm torpedo tubes carrying BAE Systems Stingray lightweight torpedoes. 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. In September 2011, the Royal Navy decided to install its new radar ARTISAN to the Type-23 frigate HMS Iron Duke.

Type 23 Frigate helicopters

The Type 23 Frigates HMS Argyle, Sutherland, Montrose, Saint Albans, Iron Duke, Kent, Portland, Somerset, and Grafton carry Lynx MK8 helicopters, while HMS Lancaster, Monmouth, Westminister, and Northumberland carry Merlin MK1 helicopters.

The naval Super Lynx is anti-surface warfare, anti-submarine warfare, search and rescue, and utility operational aircraft. Merlin HM MK1 is an ASW variant of the EH101 helicopter.

The aircraft has an integrated mission system, which can process data from on-board sensors, providing Merlin with an optimal capability to search, locate, and attack submarine targets.

Countermeasures – Sea Gnat (Outfit DLB) decoys

Countermeasure 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 fitted with the BAE Systems Outfit DLH upgrade, which enables the launch of the Siren Mk 251 active decoy round and 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. It was 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.


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 was replaced by a new medium-range radar. In March 2007, the UK MoD issued invitations to tender for the radar. Bids were 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. HMS Richmond started a £20m upgrade. Upgrades include Sea Wolf, improved command and weapons control systems, and 30mm automatic guns with increased accuracy and range.

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 was replaced by the Thales Underwater Systems Type 2087 low-frequency active sonar (LFAS). It 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 were fitted with the new sonar.

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

The S2150 sonar was fitted aboard HMS Portland for enhanced operator effectiveness and usability in April 2020. The sonar is also planned to be integrated on to eight of the Royal Navy Type 23 frigates.

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 15k and the range is 7,800 miles. Maximum speed is 28k.