Type 23 Duke Class Frigate
The type 23 class frigate was conceived in the late 1970s as a light anti-submarine frigate whose primary role was to meet the then Soviet nuclear submarine threat in the North Atlantic. This new class was intended to replace the Leander class frigate, which was developed in the 1950s and the type 21 class frigate, developed in the 1960s, as the backbone of the Royal Navy's surface ship anti-submarine force. The type 23 class frigate was not procured as a replacement for the type 22 frigate.
As one of the primary workhorses of the Fleet, Type 23s spend much of their time at sea on operational taskings worldwide. Powerful and versatile with the capability to operate anywhere in the world, the type 23 frigate is the mainstay of the modern surface fleet. The 13 Type 23 frigates form 50% of the total frigate/destroyer force in the Royal Navy. Originally designed for the principal task of anti-submarine warfare, they have evolved into powerful and versatile multi purpose ships with the capability to operate anywhere in the world. The effectiveness of these ships is enhanced by their stealth design, which reduces their radar signature significantly. In addition to the war fighting roles described above, the ship is trained to conduct a wide range of other tasks. These include embargo operations using boarding teams inserted from the ship's boats or helicopter, disaster relief work and surveillance operations.
The requirements for a low noise signature and high endurance led to the adoption of a new type of propulsion system. The propulsion plant of Type 23 is CODLAG [Combined Diesel Electric and Gas Turbine, also known as CODEAG] type with each two of Spey gas turbines and electric motor powered by diesel generators. The primary role of the Royal Navy's Type 23 frigate -- the Norfolk class -- is antisubmarine operations with a towed sonar array. This aggravated the problem of widely divergent maximum and cruise power requirements, and largely influenced the choice of propulsion machinery, part of which includes the first electric drive that the RN has used in a major surface-ship since the 1920s. The class has a CODLAG installation with twin f.p. propellers. There are two Spey gas-turbines, a type capable of producing up to 14 MW, for the frigate's high-speed operation. SSS clutches are incorporated in an arrangement that allows the reduction gearing to be stopped under silent running' conditions.
The very high combined electrical load for ship's services and, during operation at the lower speeds and manoeuvring, for propulsion is met by an integrated system with four GEC Paxman Valenta Diesels as prime movers; primary power generation is at 600 V, with ship's service supply reduced to 440 V and isolated from the supply to the d.c. low-speed propulsion motors by the use of motor-generators. Vosper Thornycroft are supplying a fully-digital control and surveillance system. Overall coordination of the machinery arrangements is the responsibility of Yarrow Shipbuilders, the lead yard for the class. The reason for choosing this system, and its components, in preference to alternatives, was to meet requirements that include low cruise-power, high maximum power, fuel economy, manoeuvrability, and low underwater noise-levels.
The Ship's weapons include the Harpoon long-range surface to surface homing missile, two 30mm close range guns and the versatile 4.5 Mk 8 gun. For self-protection against any incoming air threat there is the Vertical Launch Seawolf Missile System. This comprises two tracking radars, one forward and one aft, and a silo containing thirty-two missiles. The Ship also boasts a Magazine Torpedo Launch System which allows the launch of torpedoes from four torpedo tubes built into both sides of the hanger superstructure. As with the fixed Seawolf silos, this arrangement dramatically reduces the exposure of personnel on the upper deck in action by obviating the need to reload torpedo tubes or missile launchers.
Among the sensor systems are a hull mounted sonar, air surveillance radar type 996 and a sophisticated electronic warfare system, UAT, which passively monitors and recognises the electronic emissions of potential enemy ships and aircraft. At the heart of these systems is an advanced computer based command system connected to the combat system highway. This data highway enables the computer to communicate with and control the weapon systems; it also allows any weapon or sensor system to communicate directly with any other, without going via the central command system.
When required, the Ship's weapon systems can be brought to bear by the above water weapons team, and if threatened, the Ship can defend herself against aircraft through the high-speed vertical launched Sea Wolf system, 30mm cannons and machine guns. Against a surface threat, Harpoon anti ship missiles can engage targets lying far beyond the visible horizon, while the 4.5-inch gun is utilised closer in. The 4.5-inch gun is also an effective means of providing lethal, accurate fire support to troops ashore during joint operations. Finally, the helicopter's Sea Skua missiles give Type 23 Frigate the ability to engage surface targets at arm's length; particularly effective against small patrol boats operated by many countries around the globe.
When first commissioned the complement of crew carried by Type 23 frigates was 173. The complement as of 1998 was 171. At that time there were no plans to reduce the complement of Type 23 frigates by refitting with less manpower-intensive equipment. Manning implications are taken into consideration when the Operational Requirement for future ships is considered; however, the size of the complement is affected by other considerations such as the manpower needed for damage control and fire-fighting. On the type 22, the three batches have different complements, but they range between 224 per ship and 273. The type 23, depending on which book one reads, has between 157 and 173, so the complement of a type 23 is about four fifths the complement of a type 22, although they do the same job. In a way, that is good, because it means that the ship can be smaller, so it can be built for less money, it uses less fuel and less materiel, and one is paying fewer sailors.
The Type 23 Frigate was designed with the expectation of spending a high proportion of its operational time in the demanding and stressing environment of the North Atlantic. The nature of the threat has evolved with resultant changes to operational priorities and deployments, the consequence of which is that these ships spend less time in the North Atlantic. An opportunity has therefore arisen to extend the interval between major maintenance periods. Improved processes for the specification and management of equipment maintenance are also being introduced. The collective effect of these developments is to increase the availability of Type 23 Frigate capability for operations. Type 23 frigates achieved approximately 85-89 percent average availability for operational service in each of the five years 1993-1998 with the exception of 1996 when the figure dropped to just over 80 percent due to a number of ships experiencing a particular defect. This discounts time spent in planned maintenance.
The actual cost per annum of operation for ships such as Type 23 frigates, Type 22 frigates, SSNs, Hunt Class minehunters and Sandown Class minehunters will vary considerably dependent on the tasking/maintenance undertaken. Indicative annual costs, including manpower, fuel and stores only, would be in the region of £16 million for a Type 23 and a Type 22 frigate, £11 million for an SSN, £3 million for a Hunt Class minehunter and £2 million for a Sandown Class minehunter.
