The Type 23 ‘Duke class’ Frigate: A Guide

The Type 23 programme originally arose in the late 1970’s, at the height of the Cold War.

At the time Britain was locked in a pre-apocalyptic arms race with the Soviet Union, and thus all developments across the three services were geared to one thing: World War III. In few places was this more keenly felt than the navy, for whom this mean open-ocean symmetrical warfare against the Communist forces.

To be precise, Anti-Submarine Warfare. This was due to the fact that Western war plans were centred on the concept of a submarine rush through the GIUK (Greenland-Iceland-United Kingdom) Gap.

The Soviet navy was very much based around deepwater submarine operations, and was building up a formidable fleet of SSNs- Nuclear-powered attack submarines. Their naval tactics were centred around flooding the Atlantic with these hunter-killer boats, sinking Military and Merchant ships alike. While surface ships did of course feature, they existed to follow the submarine squadrons in, supporting them and mopping up with anti-ship missiles and light air cover (the Kiev class is an excellent example of this, a jack-of-all-trades pocket carrier/ guided missile platform intended to support SSN operations).

This was in sharp contrast to the US navy, which at the time was building a more balance force centred around Carrier Battle Groups. As the first in the firing line, Britain would have to change- and so in the 70’s, we did.

Having already lost our battleship in 1960, we now focussed on cutting the large, catapult-equipped carriers and instead moved towards dedicated anti-submarine operations. This we did, instead designing a three-ship class of light ASW carriers, the legendary Invincible Class, which initially were envisaged to be primarily helicopter equipped, flying the equally legendary Sea Harrier for the purposes of air cover, primarily not against Soviet naval aviation but long-range Maritime Bombers. So, this is how things stood in the late 1970’s: ASW operations, ASW operations and ASW operations.

Naturally, the centre of these plans would be the Frigate. Whereas our destroyers (at the time, the Type 42 Sheffield class) were designed for anti-air warfare, playing escort to the carriers, frigates would be the hunters of the force, ranging far and wide to track and kill the ‘reds’. At the time, we operated three classes of frigate: the venerable Leander Class, dating back to 1960, which had been the one-size-fits-all post-WWII frigate which was now specialising in the submarine work with a class of 26 vessels, the 1974 Type 21, a more general escort with a more modern design and a class of 8, and the upcoming Type 22, a fully specialised sub hunter that was under construction in the late 70’s with a class of 14.

The plan was design a light ASW frigate that would be able to act in support of the larger Type 22, providing the wide coverage that was all-important to ASW operations. The intention was for this to be a fully specialised ship, with a towed array- the latest must-have convenience for the modern sub hunter- and be able to carry a small helicopter to deal with them. It was to be given no defensive armament, a rather staggering prospect to today’s world of multiroling, and was envisaged to be fielded in squadrons of four.

Each of these far-ranging units would be supported by a Fort Victoria class replenishment vessel, which would be operating as a sort of catch-all mothership, providing air cover with Sea Wolf AA missiles and with hangar facilities to service the helicopters of the frigates (something that the ships themselves would be lacking). But, perhaps fortunately, this never came to pass.

In 1982, the Argentine Junta invaded the Falklands Islands, a far-flung British colony in the South Atlantic. When the taskforce sailed, they rapidly found themselves under air attack, and the loss of several vessels and the damaging of several more rapidly made several things clear:

• Aircraft still indisputably posed a threat to ships.
• Centralised Air Defence may not be enough: ships would need the ability to defend themselves.
• The Argentine anti-shipping attacks had come in two forms: the Exocet, a terrifyingly effective and very modern sea-skimming missile that would require up-to-date tracking measures to detect and modern interception technology to take down, and older conventional bombing. While we were immensely fortunate in that very few 1000pd bombs dropped actually detonated (if the argentine air force had realised the fuse problem at the beginning of the war then subsequent events would have been very, very different) there was still a salient point there. What this proved was that air defence was simply crucial for vessels.

After the war, the Type 23 program rapidly began to evolve. First to appear was the very significant decision to include a VLS (Vertical Launch System) equipped with Sea Wolf, which in turn meant a larger radar and tracking suite, which would be crucial for dealing with anti-ship missiles. With the ship growing to accommodate the VLS and the extra super structural equipment, the two main additions were placed in to make this once and for all a larger and more complex design: a multirole Naval Gun (something that had proved its worth for anti-shore work in the Falklands) and a hangar, which was a simple practicality now that the hull size had grown.

With a gun, hangar and VLS added, followed shortly by a Harpoon system, the Type 23 had become a large all-rounder that, while maintaining its ASW capability, had become a self-contained vessel in its own right- and the rest, as they say, is history. Surfing on the wave created by rapid rise of pro-Naval sentiment in parliament created by the Senior Service’s time in the limelight during the Falklands (including the tearing up of the 1981 review, but that’s a story for another day), the ship had become a colossally flexible vessel that now eclipsed the Type 22 itself- primarily because it had been amended post-Falklands, which meant that they could work with an essentially clean slate. Overall 16 were built, with the class being named the Duke class after the common theme of the names being, you guessed it, Dukes.

The first ship, Norfolk F230, was laid down in 1985 and finally launched in 1990, and the final ship, St. Albans F83, was launched in 2002. By that point the Berlin Wall had fallen and the Cold War had ended, meaning that the focus would once more shift towards more general naval operations. It is this that makes the Type 23 so interesting as it was designed during the Cold War yet launched and operated entirely after it- and so these post-Falklands design changes, seen in the ASW navy as being somewhere between useful but not necessarily and overly complicated were now the reason that the class had been saved. By diversifying its capability, the Government had unwittingly secured its future.

The Type 23 displaces a total of 4900 tons, with a length of 133m, a beam of 16.1m and a draught of 7.3 metres. This can be compared to the Type 22 Batch 3 (in many ways a similar vessel, though without a VLS), displacing 5300 tons and 148.1m long, the Type 21, 3360 tons and 117m long, and the Leander class, 2962 tons and 113.4m long. The Type 23 has a complement of 185, relatively low for the period, which was largely due to experiences in the Falklands.

The Type 23 is propelled by a CODLAG Diesel-electric/gas system including four diesel generators and two Rolls-Royce Spey turbines, as used in the Type 22, not to mention frigates and destroyer export orders worldwide. The given top speed is 28 knots, although Sutherland has achieved 34.4 knots under trials. The range of the vessel is 7500 nautical miles at 15 knots, a vast improvement over the 1200 nm of the Type 21. This endurance is crucial to the role that the T23 occupies in the modern day- more of that later.

The most noticeable item that the ship is equipped with is the BAE Mark VIII 4.5” Naval Gun. It is essentially identical to that operated by the Type 42 and 45 destroyers. Between 2005 and 2012, the 13 remaining ships all had their guns upgraded to the Mod 1 standard by Babcock Marine, noticeable for its stealthy design. The ships are also currently having their DS30B 30mm guns replaced by the newer DS30M, designed for close-in defence against fast moving attack craft.

The anti-air warfare is provided by a 32-cell VLS system designed for the Sea Wolf missile system. The original Sea Wolf (of Fort Victoria intention) was in a non-VLS launch design, which was problematic due to the issue of the hull of the ship getting in the way of the missile launch (another problem identified in the Falklands).

With a VLS (a new innovation for the 80’s and famed for it’s key role in such famous designs as Arleigh Burke), the missiles could clear the hull of the ship before igniting, vastly improving the anti-capability over the originally planned conventionally launched missiles. Considering that the ship was intended to have no anti-air capability at all, that is rather impressive! Currently, the Sea Wolf missiles are being replaced by the newer Sea Ceptor CAMM design, notable for the fact that four missiles can fit into one Sea Wolf VLS tube. This gives Type 23 excellent self-defence AA coverage.

The anti-submarine capability is provided by Stingray anti-submarine torpedoes, fired from two tubes. In addition to that, the Type 23 can carry a single Merlin HC1, the airborne submarine hunter of the Royal Navy and sometimes quoted as the ‘flying frigate’ for obvious reasons. The Merlin is equipped with dipping sonar, sonobouys and depth charges, ideal for ASW operations.

The anti-shipping capability is provided by the ubiquitous Harpoon missile, a US designed anti-ship missile was originally launched in 1977 and since then has provided both the US and Royal navies (not to mention many others) with excellent anti-surface capability- made all the better by the fact that the missiles are stored in simple bolt-on racks rather than a more complex deck-penetrating VLS system, which would potentially make reloading a more complicated affair. The Type 23 has two of these four-missile racks.

Currently, the Type 23 is undergoing as a class the replacement of the older Type 996 radar with the newer and far more capable Type 997 Artisan 3D radar system. This is reportedly 5 times more capable and will also be fitted to the Queen Elizabeth and Albion classes. The ships are fitted with two Marconi Type 991 systems for fire control, linked up to the aforementioned Sea Wolf system. This provides vastly superior radar coverage to anything that we operated in the Falklands, and will be the key to identifying and downing any incoming offensive action in any future conflict.

In the ASW department, the ships are also fitted with a Thales Type 2050 bow sonar array. In addition to this, five of the Type 23s are equipped with Type 2031Z towed sonar arrays, with the other eight bringing Type 2087 to the table. Factor in the airborne ASW capability, and the end product is a vessel with simply superb anti-submarine capability that leaves us in absolutely no doubt as to what it was originally designed for! Kelvin Hughes Type 1007 and Racal Decca Type 1008 provide navigational coverage, with the Sea Archer 30 being in charge of fire-control. The CMS, or Combat Management System, is provided by BAE Systems with the Command System DNA.

Throughout its lifetime, the Type 23 frigate has been at the forefront of British overseas activity. They are regularly used in drug-interdiction raids in the Caribbean, with raids netting millions in cocaine or heroin. They have been used in disaster relief operations in overseas territories and beyond, and even in the evacuation of British civilians from Libya in 2011 during Operation Ellamy.

Over the last 20+ years, whenever a British carrier or assault ship has left port, there has always been a Type 23 to be seen nearby, prowling the surrounding waters.

They have been true messengers of British strategic intent, and will continue to do so until 2036, when the new Type 26 Global Combat Ship- Type 23 on steroids would be a pretty good way of describing it- will replace the last ‘Duke’ class. The fact that that is another 24 years away shows that the best out of this excellent piece of British design is still undoubtedly yet to come, and Amen to that!