Concept

The Type 23 frigate is a true child of the Falklands War, as it represented the first occasion in which the painful lessons of the South Atlantic could be applied to a new class of ship.

The Type 23, or Duke class, was conceived in the late 1970s as an anti-submarine warship which could hold its own as a general-purpose weapon platform - in other words, a specialist submarine hunter but also a good all-rounder.

At about the same time the idea of the EH-101 was emerging from the wreckage of the WG34 programme, and these two resulting machines - the Type 23 frigate and the Merlin helicopter - progressed very much in tandem, with an eye to their combined capabilities.

When the first Type 23 orders were placed in October 1984 with Yarrow Shipbuilders at Scotstoun on the Clyde, who acted as designers and lead builder, the Duke class was to be first and foremost a series of ultra-quiet anti-submarine ships.

But the Falklands War of 1982 had a crucial role in the evolution of the design - for example, the major elements of the Type 23's weapon fit were not finalised until after the construction contract was signed, so rapid was the development of weapons systems.

Among the areas of particular concern were the ships' survivability, and their ability to defend themselves in combat. As a result, the Type 23 packs a bigger punch than many similar-sized ships, and its structural features qualify it as a genuinely 'stealthy' vessel.

The class remained, at the bottom line, an anti-submarine ship, and the Dukes were expected to patrol the deep waters of the North Atlantic with a towed sonar array which could pick up and track the sound of Soviet submarines.

Confused sonar patterns in shallower waters were to present fewer problems to the Type 23 than to earlier ships as the frigate's propulsions system was also designed to radiate as little noise as possible, both to avoid confusing the ship's own sonar, and to prevent the Royal Navy warship being detected by its prey.

The need to operate the Merlin helicopter - a bigger and heavier aircraft than the Sea King - was a major factor in the size of the vessel, and the fact that an aircraft is available for operations to a much higher degree when there is a sheltered environment in which to maintain it determined that the frigates would have a hangar.

As the design became crystallised and the time approached for the cutting of steel at the Glasgow shipyard, the Type 23 was expected to become a mainstay of the NATO fleet as it sought to contain Soviet forces in the far North, and to contribute to other operations in the Atlantic and other, shallower, seas.

It was certainly designed to form the backbone of the Royal Navy's surface flotilla, making up around half of the destroyer-frigate force - the workhorses of the modern Navy.

Top of Page

Stealth

Type 23 frigates were the first ships designed for the Royal Navy as stealth vessels, and as such, 'signature reduction' - the elimination of as much noise, heat and reflection as possible - was an important factor in the shape of the hull and installation of machinery.

The two principal signatures addressed by the Duke class are noise and radar cross-section.

Modern anti-submarine ships need to be quiet to avoid interfering with their own sonar systems, both hull-mounted and towed, and so the need to cut underwater noise has been paramount.

The choice of propulsion system - a combined diesel electric and gas turbine layout - is unusual for the Royal Navy, but fits the bill perfectly.

When required to sprint, the two Rolls-Royce Spey gas turbines feed 23.2mW through a GEC gearbox to two shafts, allowing the Type 23 to reach speeds approaching 30 knots.

But while tracking a contact, when silence is vital, the ship is powered by two GEC electric motors, connected directly to the shafts and turning two big low-speed revolving propellers. This means the noisy gearboxes, lubricating pumps and other linked machinery can be shut down, eliminating clutter in the sonar picture.

All noise-generating machinery has been identified and isolated by insulating material, or by being placed on acoustic rafts, and hull vibration equipment monitors unusual noise to help identify particular problems from within the ship.

Meanwhile the radar cross-section - the size of the target the ship presents to an enemy radar operator - has also been addressed.

The strength of the echo a ship presents is not directly related to its size - modern radar reflectors on small yachts and fishing boats present large radar cross-sections - but to other factors such as the wavelength at which the radar illuminates its target.

By reducing this cross-section, the chance of an enemy radar-guided missile locking-on is reduced, and there is consequently a better chance of decoys distracting the incoming missile.

Because the main threat was perceived as being from sea-skimming missiles, with a single combined transmitter and receiver low on the horizon, the geometry of the Type 23 was designed to prevent radar beams being reflected back to the missile.

The superstructure has a seven degree slope to all vertical surfaces, and all edges are rounded, while the 133-metre hull is noticeably flared along its length; this means the horizontal radar beams of the enemy missile are scattered harmlessly into the sky or sea, and not back to the weapon.

Just as importantly, deck fittings and equipment have been reduced as much as possible, and that which remains is designed to present a minimal signature; all the good work of the hull and superstructure design could have been undone with a poorly-designed locker or housing.

Top of Page

Anti-submarine

The Duke class is an effective submarine hunter - and when it finds its target, it possesses the ability to do a lot of damage.

Towed sonar arrays - Type 2031 in the first ten of the class, with the remaining six expected to be fitted with the new Type 2087 from the middle of the decade - and the hull-mounted Type 2050, in a bow dome, pick up the sound of a submarine at considerable distances.

Towed arrays are most effective when streamed out behind the frigates at a low speed in deep, quiet water, and contacts can be cross-checked against known surface shipping in the area to refine the search for an enemy boat.

Merlin will add the icing to the cake by providing a fast, long-range pinpoint capability - it can fly off to check a particular sound with its dipping sonar, and data from the aircraft will be sent direct to the ship, effectively extending the anti-submarine clout of the Dukes by hundreds of miles.

If an attack is deemed necessary, the Merlin can deliver up to four lightweight Stingray homing torpedoes or depth bombs at some distance from the mother ship; if the contact is at close quarters, the Duke class can also fire Stingrays from two sets of twin launch tubes.

Top of Page

Self-defence

Again, the Falklands War provided a painful reminder of the need for effective self-defence for any ship, and the Duke class reflects that lesson.

Type 23 frigates now operate worldwide as singletons - on their own, maybe with just a small Fleet tanker for support - but can just as easily be called in to act as a close escort for a task group.

The first line of defence for the frigates is the electronic warfare (EW) suite and air-warning systems, vital in an anti-air warfare (AAW) scenario.

The latter is centred on a flexible, three-dimensional radar system, Type 996(1), which scans for and identifies both high-level aircraft or diving missiles and sea-skimming threats, linking in to the ship's combat system to allow such threats to be dealt with quickly.

Merlin, with its Blue Kestrel 5000 radar, can also act as an airborne early warning (AEW) aircraft in such situations.

Once identified, an aerial threat will most likely be dealt with using the vertical launch Seawolf system; the vertical launch pattern is particularly useful in that there is no 'blind spot' on the ship - any missile can be handled by the most convenient fire-control tracker, whereas older systems tied a missile to a particular tracker, which might be at the wrong angle to counter the incoming missile or aircraft.

Seawolf missiles are situated in a rack of 32 canisters just forward of the bridge, breaking through the cover of the tube when launched and clearing the ship before discarding the launch booster motor and turning to meet the threat.

In addition, ships of the Duke class have two 30mm power-driven anti-aircraft cannon amidships, and the Vickers 4.5in gun forward of the Seawolf launch system can also knock aircraft out of the sky.

Passive defence is provided by a Sea Gnat decoy system and electronic jamming devices, and a towed torpedo decoy may be deployed.

Top of Page

Attack

In addition to the anti-submarine warfare capabilities outlined earlier, and those systems primarily designed for self-defence, the Type 23 frigate has a number of attacking weapons.

The Vickers Mk 8 4.5in gun is primarily fitted for naval gunfire support operations, banging off 21kg shells to a distance of more than 12 miles, and it can just as easily be used against ships.

Duke-class frigates also carry Harpoon missiles as the principal weapon in dealing with the threat from other warships or surface targets; these missiles carry a hefty warhead more than 70 miles at close to the speed of sound, using radar to home in on the target in the final stages of the attack.

If a Lynx helicopter is carried, then air-launched Sea Skua anti-ship missiles are also available.

Top of Page

The ship's company

A warship, as the Royal Navy will never tire of telling you, is only as effective as the men and women who fight it, and in the case of the Type 23 frigate, they are a highly-skilled and select group.

For a ship of its size - 4,200 tons, when fully loaded - there is only a modest requirement for up to 180 people, of whom just over a dozen will be officers. The Duke class are a good example of the Royal Navy's lean-manning policy in practice.

Extensive automation means that many of the critical systems are computerised - from the weapons and sensors, through the main engines and electrical distribution systems, to the catering accounts and pay and personnel records.

The ship's company is divided into various departments within the ship, with the Operations Department being at the sharp end.

The Operations Department is itself split into five distinct divisions: missile, sonar, radar, electronic warfare and communications.

The Missile Division man the Seawolf and Harpoon systems, and - somewhat anachronistically - the 4.5in gun.

Sonar Division are responsible for manning the submarine detection systems, while Radar Division looks after the radar displays in the Operations Room ('Ops Room') and plot data received from other ships and aircraft.

Electronic Warfare (EW) ratings analyse electronic signals of all kinds to identify which ships, aircraft or other sources are transmitting them.

The Communications Division (Comms) keep the ship in touch with shore-based headquarters and maintain tactical communication with friendly ships and aircraft in the immediate area.

The Ops Room is the heart of the Operations Department, closely linked to the Sound Room. In these two areas all the incoming data from sensors is processed and displayed, allowing the ship's commanding officer, the Principal Warfare Officer (PWO, pronounced pea-woe) and the Command Team to gauge the bigger picture - the whereabouts of friendly and enemy units in an area stretching for hundreds of miles.

Any direct threat to the ship, or to the force of which the ship is a member, can be assessed and an appropriate course of action taken - which could mean bringing one of the weapons systems to bear.

The ship's aircraft - Lynx, Sea King or Merlin are all possibilities - are also manned by Ops Department personnel

The Marine Engineering Department is primarily responsible for running, maintaining and repairing the non-weapon equipment, which includes everything from the main propulsion motors to the sanitary services and domestic facilities.

Apart from the engines, described earlier, the ME department looks after four generators which supply power for all the departments on board - whether the means to run a sophisticated missile system or simply to switch on a bunk-head lamp.

All fresh water used on board the frigates is produced from seawater by the reverse osmosis method, providing water for drinking, cooking, washing and cleaning.

The department is also responsible for the distribution systems by which water, fuel, oil and ventilation are delivered to the point at which they are needed.

And while integrated circuits and other modern technology means systems are controlled and monitored automatically, the computer age does not mean the human touch is redundant - highly-skilled artificers and mechanics are needed to operate and maintain the equipment.

The levels of knowledge required in both electrical and mechanical fields means the ME department contains some of the most highly-trained personnel in the Navy.

The Weapon Engineering Department maintains the ship's sensor, communications and weapons systems, which in the Duke class includes the Vertical Launch Seawolf close-range defence system.

Seawolf consists of two tracking radars, one forward and one aft, and a silo of 32 missiles which are launched automatically.

The Type 23 also has a magazine torpedo launch system, allowing Marconi Stingray torpedoes to be fired from within the ship itself through doors on either side of the hangar superstructure and then reloaded automatically.

Among the sensors under the care of the WE Department are the 996 radar, Ferranti/Thomson Sintra Type 2050 bow-mounted sonar, and the latest in electronic warfare, the UAF system, which passively monitors and identifies radar emissions which reach the ship.

At the heart of these systems is a computer-based command system, which not only communicates with and controls weapons and sensor systems, but also allows these systems to pass information between themselves independently of the command system itself.

Finally, the department is responsible for the ship's integrated communications system, which gathers and distributes incoming messages, and transmits information from the ship via satellite or radio links.

Once again the men and women in the department are trained to a much higher level than has been needed in the Navy in previous decades, and they use a battery of diagnostic tools to ensure all defects are rectified immediately, and all maintenance is up to date, to keep the ship fighting fit.

The Supply and Secretariat Department provides logistic support, administration and 'hotel services' for the ship.

It is split into several sections, including the Stores Accountant, Chef, Caterer, Steward and Writer specialisations, as well as the civilian roles of NAAFI canteen manager and laundry manager.

Stores Accountants are responsible for six major store rooms which contain up to 18,000 different items valued at well over £1 million.

The majority of these spares are vital parts used in the maintenance of the frigate's weapon, propulsion and ancillary systems, and to help them the SAs have a computerised stockholding and stowage location system.

The Chefs, supervised by a Petty Officer Caterer, ensure the ship is fully stocked with the food and drink needed to provide a balanced and varied diet for the ship's company, and once again they are helped by a bespoke computer system.

Cooking is undertaken in a single galley, from where it is served to the two dining halls or transferred to the Wardroom.

Stewards ensure the day-to-day smooth running of the officers' mess on board, although they are also responsible for the organisation and presentation of formal functions on board - during a deployment, they will be expected to rise to the occasion on a regular basis as visiting VIPs and dignitaries are welcomed on to the frigate.

The Ship's Office is the administrative centre, where Writers co-ordinate pay, cash, personnel records and correspondence, and once again computers now play an important part in the organisation of their work.

The two civilians on board are the NAAFI manager and the laundry manager.

The NAAFI manager runs the canteen services for the ship's company, stocking everything from shampoo to beer and chocolate to shoe polish. The NAAFI is also regarded as a good place on board to catch the buzz - find out what's going on around the ship and beyond.

The laundry manager provides a same-day service on cleaning services on a repayment basis.

Top of Page

The Type 23 frigate in service

Early plans allowed for up to 23 Type 23 hulls, but the class has now completed with a total of 16 frigates, the last of which is HMS St Albans.

The first of the class, HMS Norfolk, was ordered from Yarrows in October 1984, with the final three being ordered almost 12 years later, in February 1996.

HMS Lancaster, the third of the class, was originally given the pennant number F232, but that was changed to F229 as 232 was regarded as unlucky - 232 is the number of the Royal Navy's report form for groundings and collisions.

The full list, with (pennant number), builder, date of launch and date of commissioning, is:
HMS Norfolk (F230), Yarrows; July 10, 1987; June 1, 1990
HMS Argyll (F231), Yarrows; April 8, 1989; May 31, 1991
HMS Lancaster (F229), Yarrows; May 24, 1990; May 1, 1992
HMS Marlborough (F233), Swan Hunter; January 21, 1989; June 14, 1991
HMS Iron Duke (F234), Yarrows; March 2, 1991; May 20, 1993
HMS Monmouth (F235), Yarrows; November 23, 1991; Sept 24, 1993
HMS Montrose (F236), Yarrows; July 31, 1992; June 2, 1994
HMS Westminster (F237), Swan Hunter; February 4, 1992; May 13, 1994
HMS Northumberland (F238), Swan Hunter; April 4, 1992; November 29, 1994
HMS Richmond (F239), Swan Hunter; April 6, 1993; June 22, 1995
HMS Somerset (F82), Yarrows; June 26, 1994; September 20, 1996
HMS Grafton (F80), Yarrows; November 5, 1994; May 29, 1997
HMS Sutherland (F81), Yarrows; March 9, 1996; July 4, 1997
HMS Kent (F78), Yarrows; May 27, 1998; June 8, 2000
HMS Portland (F79), Yarrows; May 15, 1999; May 3, 2001
HMS St Albans (F83), Yarrows; May 6, 2000; to be commissioned

Top of Page

Join Ship of the Month and receive a new postcard sized photograph every month!
Each month Navy News looks at a different ship, her compliment, armoury, propulsion and her recent activities. Join the many subscribers who have been collecting Ship of the Month since 1969.more>