7

The Later Frigates

DURING THE EARLY 1960s the escort programme centred on the Type 82, primarily an AA ship, but with a considerable AS capability. It was a very expensive ship, so escort numbers could only be maintained by building in parallel very cheap frigates, mainly for limited war. It was hoped that the numerous Leanders would fulfil the AS role for some years. There were some studies for a bigger AS ship, the Type 17 (see Chapter 6), but these were not developed. The only long-range sonar sets were hull mounted, big, requiring a great deal of power and very expensive (see Matapan below). There were numerous attempts at a cheap, capable AS frigate but none was successful until the towed array was developed.

The Type 19 Designs

In the mid-1960s the Admiralty hoped to retain an escort force of some ninety destroyers and frigates, which led to a requirement for four new ships each year, each with a 21-year life. Ideally, all should deploy Sea Dart and Ikara, implying ships similar to the Type 82 (Bristol). Forecast budgets of manpower as well as money made such a force impractical and attention turned to a mixed force with a considerable number of cheaper ships requiring small crews. Between 1971 and 1976 it was hoped to complete eight Type 82s and thirteen Type 19s. The balance of twenty-four ships would include the last two Leanders and the first of a Type 82 replacement.

In peacetime the role for the cheap ship, referred to as the Type 19, would include: police, patrol and general peacekeeping duties, including operations against fast small craft engaged in gun-running, smuggling and infiltration, counter-insurgency, fishery protection, disaster relief and showing the flag.¹ In limited and general war it would contribute to the AS escort of a unit in conjunction with more sophisticated vessels. The ship would have an anti-FPB capability for which very high speed was necessary, and also a naval gunfire support capability. She should be capable of a measure of self-defence against air attack.² It was hoped to approve the Staff Requirement in mid-1965 and order the first ship at the end of 1967 for completion at the end of 1970. The principal requirements for the peacetime role were seen as a medium-calibre gun,³ a light helicopter, accommodation for 30 troops, long endurance (5000 miles) at 15kts and very high speed for a short burst (c40kts), sustained top speed 28kts. For war it needed a medium range sonar, torpedoes for the helicopter (Wasp), Sea Cat⁴ and limited AIO/EW. In the light of her limited AIO, her weapon systems (Match helicopter) would be directed by a more capable escort.

An early design study showed a 1900-ton ship, 340ft long by 35ft beam. The power available (tropical) would be 64,000shp from two shafts, each having two Olympus gas turbines. There were also two diesels per shaft for cruising.⁵ Endurance figures are of interest, particularly in light of future developments, discussed later.

The ‘Battle’ class destroyer Matapan went into reserve at the end of the war having only completed acceptance trials. In 1971 this ‘low mileage’ ship was rebuilt as a sonar trials vessel, with an array some 100ft long and a hull packed with the ultimate in valve technology. Though this sonar did not enter service, a great deal was learnt about big hull-mounted sonars. (The USN planned a similar trial in the Spokane which was abandoned.)

(Mike Lennon)

Speed (kts)	Endurance (nm)	Engines in use (per shaft)
39	700	2 Gas turbines
28	1100	1 Gas turbine
20	1700	1 Gas turbine
18.5	4700	2 Diesels (not recommended)
15	7500	1 Diesel

For comparison, Leander endurance was quoted as 1200nm @ 28kts, 3530nm @ 18kts.

The gun was specified as a single 4.5in Mark VIII.⁶ Complement was 110 (+ 30 troops). This depended on the availability of some automated AIO equipment, then under development. Sonar was Type 177.

The cost was estimated at £5 million and it was emphasised that this was a firm figure, justified as there was hardly any new equipment going into the ship. It was claimed that the cost of a Leander built in the same timescale (1970s) would be £9–10 million (as quoted then, but other papers from that date suggest about £6 million for a Leander). It is almost unbelievable that this high-performance ship could be built for half the cost of a Leander! Problems envisaged in 1965 were the design of a sonar dome that would have to stand up to speeds of 40kts or be able to be retracted. The propeller design was seen as a problem, mainly from the noise at lower speeds (see later), whilst there were unspecified problems expected with the diesels for cruising. None were then thought to be difficult to solve.

About this time A N Harrison (the DNC) compared the Type 19 with earlier ships, showing how the new design was dominated by space.⁷ The internal deck area was only 2 per cent (550ft²) less than that of the big destroyers of the Daring class, while the armament weighed 180 tons compared with 410 tons in the Daring yet the space for armament and AIO was virtually the same. The machinery, generators, switchboards and the like weighed 480 tons against 870 tons in the Daring, but required 90 per cent of the space. In the Type 19, store rooms were doubled in size, offices and workshops were up by 35 per cent and space per man raised by about 30 per cent.

Within a year the concept had changed radically.⁸ In the light of the Indonesian confrontation (1962–6) the requirement was to cruise to Singapore at 40kts, implying a trials speed of 43kts⁹ – note the endurance quoted above of 700 miles at 39kts, so needing many refuellings which would much reduce the average speed. Worse was to come. The propeller loading was very similar to a scaledup ‘Dark’ class fast patrol boat propeller which, initially, had a life of 20 minutes at 40kts – even the best only increased this to 20 hours.¹⁰ Therefore, many propeller changes would be needed en route to Singapore.¹¹ The new First Sea Lord thought it was silly to send the world’s most expensive propellers into shallow water to chase motor boats – only a Third World navy could afford it!

In the quest for speed the Staff gave some thought to a 50kt hovercraft with frigate capability. They eventually suggested a paper study that would cost £35 million with no guarantee of success. To expose this nonsense the author did a quick study of a 50kt ‘conventional’ frigate. It had a Whitby hull form and four shafts each with two Olympus. The 50kt speed brought the propellers into the super cavitating regime where the design was much easier – they were CP propellers, closely based on those of the ‘Brave’ class fast attack craft, and should have presented no great problem. All the technology was in existence and the costing section came up with a price tag of £13.5 million. The Staff response was: ‘We don’t want a 50kt frigate’! However, it did kill the hover frigate.¹²

The original plan for a mix of Type 82s and cheap Type 19s had some merit. This author’s views on what is now called the HILO mix are given at some length in another book which suggests that the cheap ship should be first-rate in a limited role, like the Type 14 (Blackwood).¹³ This is a rather lengthy account of a ship which was not built, but it was important in the search for a cheap frigate and led to the Type 21 and the Future Light Frigate studies, and hence eventually to the Type 23. The Future Fleet Working Party studies, described in the previous chapter, led to the Type 42 for AA work and the Type 22 for ASW.

Type 21, Amazon Class¹⁴

The Future Fleet Working Party, following the cancellation of CVA-01 in 1966 discussed in Chapter 6, saw the need for a cheap frigate to replace the Leanders. It was not fully understood in Whitehall that a cheap and effective frigate was not possible with the weapons and sonars of the day – Broadsword was the smallest effective ship. It had become obvious, after long argument,¹⁵ that gas turbine propulsion offered large savings in engine-room complement and was necessary above all for this reason. Whitehall – and the Controller, Horace Law, in particular – had been impressed by the performance of the Vosper Thorny-croft (VT) Mark 5 frigates for Iran, the first all gas-turbine frigates to be built in the UK. It was believed in Whitehall that a VT frigate for the RN could be built for £3.5 million compared with the current price of £5 million for a Leander.¹⁶(Amazon was actually to cost £14.4 million, but much of the increase was due to inflation.)

The new building programme was said to be too great for Ship Department to handle alone, particularly on the electrical side, and it was generally accepted that the cheap frigate could be designed in industry. However, attempts by the Controller to prevent any involvement of Ship Department led to friction and real problems. Many standard design procedures were unwritten, based on common education and training at Greenwich and were hard to codify in the context of a binding contract (see Chapter 12 for stability standards). The Type 82 section were considering the adoption of standards based on those of the USN (Sarchin and Goldberg), and these standards had already been adopted by Vosper Thornycroft for their Mark V frigates. Ship Department remained responsible for stability and strength and asked for major changes to length and beam at the end of the first phase of design so that the new standards could be met in the Average Action condition.

Amazon, a Type 21 frigate designed by Vosper Thornycroft. The broad transom gave a good helicopter deck at the expense of increased drag, reduced later when transom flaps were fitted. Four Exocet launchers were later fitted in front of the bridge.

(D K Brown collection)

As completed they mounted the new 4.5in Mark VIII gun and carried a small helicopter. After the first two ships, they carried four Exocet MM38 SSMs. They introduced what was to become the standard frigate machinery fit of two Olympus, two Tyne giving a top speed of about 30kts, discussed in the previous chapter. They had a large transom which as they put on weight sank deeper in the water reducing speed. After prolonged argument within Ship Department and Haslar, it was finally agreed to try a flap (elevator) under the transom, which gave a 1.5kt increase in speed when tried in Avenger.¹⁷

Much of the argument over the performance of the class has been concerned with the aluminium superstructure, which was a load-bearing part of the hull girder. An aluminium superstructure is only about half the weight of a steel structure and the lesser topweight permits a reduced beam with further important savings. Attacks on the concept are mostly unsound: aluminium in structural form does not burn, as often claimed, but it does soften at 550° and melt at 650°C. Since a typical oil-fed fire reaches 900°C, it is clear that melting aluminium may add only slightly to what is already major damage. Two Type 21s were lost in the Falklands but in neither case did aluminium contribute to the loss. It is also suggested that the joint between the aluminium and steel structures would lead to corrosion, but this was a well-known problem and the solution adopted by Vosper Thornycroft has given no problems in service.

The one real problem was fatigue cracking in the aluminium, which has a much shorter fatigue life than steel. Cracking in 01 deck began to occur early in service life and got worse. Initially, palliatives were adopted, perhaps the best being patches of carbon-reinforced plastic glued to the aluminium – up to 10ft in length. These cracks were troublesome but not worrying as it was believed that even if the aluminium structure failed completely, the steel alone would cope with almost any loading. Then, in 1981 NCRE discovered, in the course of some basic research, that there was a previously unrecognised failure mode which could lead to the sudden collapse of the steel structure if the aluminium had cracked badly. Whitehall took some convincing, but eventually a study by Lloyd’s confirmed NCRE’s work. The Falklands conflict broke out before remedial action could be taken and the Type 21s went to war advised to avoid excessive motions. The aluminium structure of Arrow was extensively damaged whilst rescuing survivors from Sheffield and she was confined to San Carlos Water until a steel reinforcing beam could be fixed in place. After the war, external stiffening was applied at the top of the sheer strake and, 20 years later, the six survivors of the class continue to give good service in Pakistan. Great attention was paid to accommodation, which was unusually spacious, accounting in part for their popularity in the RN.

About 1978 a modernisation scheme was produced which would have given them Sea Wolf and better sonar. Both stability and strength required attention but a solution was found. However, R J (‘Jack’) Daniel (DGS), who had been involved at the start, recognised that freeboard to 2 deck – the highest watertight deck – was inadequate, and modernisation was abandoned. The Type 21s had a single ventilation system and electric cables under 1 deck passed through openings in the bulkheads which allowed smoke to spread in a fire.

Type 22, Broadsword Class

The Type 22 was conceived as an updated Leander and there was more similarity than is obvious. In particular, the new ships were to be as good or better sea boats than the Leander, so the hull form was very similar to the earlier success. Initial studies were carried out by Jack Daniel, then head of forward design. It was hoped that it would be a collaborative design with the Netherlands but for a variety of reasons this fell through.¹⁸ The length was limited to the then size of the Devonport Frigate Complex.

The Type 22 was proclaimed as the first ‘metric’ design. However, many equipments were designed in Imperial units and, particularly in the machinery area, it was required to retain standardisation with the Types 42 and 21. The risk of error when working in unfamiliar units is obvious but, perhaps because it was so obvious, no problems were experienced.

It is often asked why two ships so different but of roughly the same size, Types 22 and 42, were designed at the time. (See also Chapter 6 for the Working Party attempts at a common hull, and there were studies for a ship like the Type 42 with Ikara.) The hull form is very different as the big Sea Dart stowage makes the Type 42 very full forward, to the detriment of seakeeping. The Type 22 has more freeboard, a much bigger hangar and flight deck and a very different armament. It would probably have been possible to design a baseline ship which could be completed to either role (‘Loch/Bay’ style), but such a ship would have been much bigger and the savings, if any, would have been small. Most of the Type 22s were built at Yarrows and the Type 42 elsewhere, further reducing any savings from a common hull. In general, they had the same Olympus/Tyne COGOG plant as the Type 42 and this was an important factor in reducing their complement to 215 (250 with margins).

They had the big hull-mounted Type 2016 sonar which could be used in passive mode but also had an active bottom-bounce capability. This incorporated the lessons from the enormous experimental sonar tried in the trials ship Matapan.¹⁹ They mounted four MM38 Exocet and had two GWS25 Sea Wolf for close-range defence, particularly giving very rapid response against submarine launched ‘pop-up’ missiles, together with a pair of aged 40mm/60 cal. Bofors Mark IX (later replaced by twin 30mm). There were also two triple sets of torpedo tubes for Stingray and two Lynx helicopters (although only one was usually carried). Various funnel designs were tried in an attempt to reduce the infra-red signature.

On joining the fleet they were criticised as too big. They were indeed spacious, in a successful attempt to ease the maintenance task, and it was hoped that there would be a space margin for future equipments. Alas, it was soon found that they were too small to accommodate the Type 2031Z towed array and its associated operations room equipment.²⁰

Yarrows were chosen as the lead shipbuilder and the Project Managers, A Bull followed by A J Creighton, set a successful management plan, Creighton being seconded to Yarrows as Technical Director in charge of building the first ships.²¹

Batch II

Even though the four ships of the Broadsword group were much bigger than the Leanders, they were soon perceived as too small for all the new equipment coming forward. They carried the Type 2031Z towed array sonar which with the CACS-1 control system needed a bigger operations room. It is also said²² that they carried the US Classic Outboard electronic warfare equipment – SSQ-72 with SLR-16 and SRD-19 – which would have demanded a further large increase in the size of the operations room.

Most of the six Batch II ships had the well tried COGOG Olympus/Tyne plant, but Brave was the trials ship for the more economical Spey. Initially the two Olympus were replaced by two SMI A (37,540shp), which reduced her speed by about 1.5kts, but in 1990–9 she received the SM1C (52,300shp), which restored the speed loss.

Broadsword, the first of the Type 22s, in February 1979 with the original (ugly) funnel. (Mike Lennon)

After the first two ships of the class, the flight deck was enlarged and strengthened to take a Sea King or Merlin helicopter and the hangar altered, though they normally carried a single Lynx. This meant a slightly wider transom. Type 2015 sonar was installed in a bow dome which led to a heavily raked bow carrying an anchor clear of the dome. There are clear advantages in good weather in operating a sonar from a bow dome where it is free from bubbles swept down the stem but in heavy weather the bow dome leads to early slamming. The balance is not an easy one to draw.

Batch III

The government approved the replacement of the four destroyers and frigates lost in the Falklands War with four modified Type 22s, the Cornwall class. They had the hull of the Batch II with Olympus/Tyne machinery. They had no specific role and were given an armament of the latest readily available equipments. The need for a gun was seen as a lesson of the war and they had a 4.5in Mark VIII on the forecastle. Eight Harpoon SSM behind the bridge replaced the Exocets, and they had a Goalkeeper CIWS as well as two or four of the new single 30mm. The hangar and flight deck can accept a single Sea King or Merlin.

Brave, seen here in May 1986, was the trials ship for the Spey SM1B engine, and also had the wider flight deck and hangar for Merlin. The Batch II ships were longer to hold a bigger operations room and towed array.

(Mike Lennon)

The Batch III Type 22 Cornwall, a replacement ship for Falklands War losses. Note the 4.5in Mark VIII forward – the value of such a weapon for shore bombardment was a lesson of the South Atlantic conflict.

(D K Brown collection)

Cheap Frigates – Types 24 and 25

Around 1970 there were numerous studies for a cheap frigate under the title ‘Future Light Frigate’ led by Jack Daniel. The records of these designs have not been found but it is clear that none was found attractive since the only long-range sonars were big, hull-mounted sets, expensive in themselves and requiring a big ship.

In 1978 the DG Ships (Daniel) suggested a cheap frigate which would be attractive in the export market and could serve in the RN as a towed-array ship – Type 24.²³ He thought it should look like the ‘Castle’ class offshore patrol vessel, as customers could be attracted by the armed ‘Castle’ and then persuaded to move up to a cheap frigate. This made sense, as customer requirements would differ and a very small superstructure as in the ‘Castle’ made feasible a range of upper-deck armaments. The RN requirement implied sufficient headroom under the quarterdeck for a towed array winch and in the engine-room for noise-insulation mountings. Towed array offered long range detection within the weight and space limits of a cheap frigate.

Daniel rejected the earlier studies and this author took over in mid-1978 with a clean sheet – or perhaps a clean screen, as it was to be the first design to use the new Computer Aided Design System, Goddess. The guiding principle was the old adage ‘if in doubt, leave it out’, spelt out in a paper jointly written by the author and his deputy, David Andrews.²⁴ A particular example was the need for a roof aerial and hence a second mast, which increased ship size appreciably, so it was left out.

Though it was a simple design, it had been thought through carefully and we were very pleased with it; we had even taken pains to give it an attractive appearance. The idea was that our outline design should be passed to Yarrows to be developed. They reduced headroom so that it could not take a towed array or engine mountings, so that there was no prospect of it being adopted by the RN (and the second mast came back). Hence there were no sales either.

We toyed with some weird variants. In one a Harrier and ski jump were worked in forward. This was a reductio ad absurdum argument to show the fallacy of such ships, then being offered by commercial builders. The maintenance spaces and staff for one Harrier are almost as big as those to maintain six. Another variant had wind propulsion for quietness (Flettner rotors). This was feasible but the auxiliary power needed for the sonar was greater than the power for propulsion, so that wind propulsion did not help much in reducing machinery and propeller noise.

When the Type 24 died we decided to go back to our original study and develop it as virtually the capability of a Type 22 at three-quarters of the cost (one mast!) – Type 25. This began to look very promising; we came up with the idea of diesel-electric cruising engines so that in the ultra-quiet mode a diesel in the superstructure with a long noise path to the sea could be used. At that time Forward Design Group were allowed – even encouraged – to freelance, though we had to seek the agreement of the Ship and Weapon Design Coordination Group at its next quarterly meeting if we wanted to pursue any study.

Just as we were beginning to see the Type 25 as a success, the new government decreed that new frigates should be limited to two-thirds the cost of a Type 22. The idea of a cost limit was novel and proved successful as there was little or no weight growth during the development of the design and there was little ministerial interference with the development of the design itself – ‘All you want if it does not cost more than £100 million’. Advanced modular construction was introduced in warship yards for the Type 23 and the reduction in building costs enabled capability to be increased within the cash limit. The target set was close enough to our Type 25 for most of that study to be used, including the diesel-electric cruising plant.

A model of the Type 24, a design intended as a cheap frigate, mainly for export, which could be completed with a wide range of armaments made possible by a relatively small superstructure and single mast. In RN service it would have functioned as a towed array ASW ship.

(MoD)

Artist’s impression of the Type 25. When the Type 24 failed to attract customers the design team developed it into a ship with almost the capability of a Type 22 at three-quarters the cost. It was not adopted, but much of the thinking, including the diesel-electric quiet machinery, went into the Type 23. (MoD)

Corvettes (c1963)

The bottom of the range was Study 352²⁵ of 1960 tons with twin diesels giving 20,000shp and a speed of 26.5kts.²⁶ Armament was a single 40mm and twin mortar Mark X, costing £4 million. Its data handling gear could transmit to an Ikara-fitted ship. For £6.5 million (Leander £5.25 million) one got a ship of 2700 tons, a 30,000shp steam plant giving 27kts, carrying Ikara (24 missiles and NDB) and a 4.5in gun.

During the development of the ‘Castle’ class OPV design (see Chapter 10), we had a model made to show at the RN Equipment Exhibition showing possible heavily-armed versions. There were no calculations to support these schemes but they were probably feasible. However, there were no customers and we did not proceed. As Christmas approached, we had a little spare effort and for two weeks the author put the section on to the design of a towedarray vessel based on the ‘Castles’. This was an interesting exercise with some more fundamental implications. The vessel had to be quiet which meant most equipments had to be to warship standards, and electrical power supplies had to be stable in voltage and frequency. All this meant building in a ‘warship’ yard with high overheads and led to an estimated price of £25 million without armament instead of the £6 million for the OPV. It would have cost about £35 million fully equipped. This is about the most expensive ship that may be seen as ‘expendable’. Giving a reasonable self-defence capability would have brought it close to the Type 23 in cost, well over £100 million. There are ‘zones’, such as this gap of £35–£l 10 million in which warships are not viable; there is a similar but bigger gap for cheap aircraft carriers.

The ship was lengthened about 10m to accommodate the towed array abaft the helicopter deck. The deck could accept any RN helicopter and there were refuelling and limited rearming facilities but no hangar or maintenance facilities. After some debate, we added a single 30mm gun ‘to prevent hijacking’. We looked at increased speed but the form was unsuitable and a better form would have involved lightweight structure, adding further to the cost. We looked very briefly at a SWATH and also at a very long range version.²⁷

Even some wind-propelled variants were considered. (MoD)

A more serious study was for an RN towed array ship. It could land and refuel a Merlin helicopter and had a small gun for protection against hijackers. (MoD)

A quick study was made of a heavily-armed corvette based on the ‘Castle’ class OPV. This model demonstrates some of the armament variations possible. (MoD)

1964 Corvette – Design Study 363. This design study dated January 1964 displaced 2075 tons. Dimensions were 320ft × 37ft. Two Ruston V16 diesels driving one shaft produced 20,000shp, which gave a speed of 26kts. The armament consisted of a single Bofors 75mm L/50 and a single Mark X anti-submarine mortar.

(Drawing by John Roberts from original in NMM ADM 1/28609)

Another study was made of a SWATH (Small Waterplane Area Twin Hull) variant patrol vessel. It could have been much smaller than a conventional craft for the same seakeeping, but there was no effort to develop the idea.

(MoD)

A later study of a corvette based on a fast catamaran.

(MoD)

An early Type 23 study. Its similarity to the Type 25 is evident. (MoD)

Another, cut-price study on the way to the Type 23. (MoD)

It was envisaged that this ship should be additional to the frigate force, adding more sensors. Our proposal was taken very seriously but rejected as it was thought the government would see it as a cheap frigate rather than additional to the force. More recently, the Parliamentary Defence Committee looked at the so-called high-low mix (HILO) with fully-capable frigates backed by cheaper, less capable vessels and these politicians rejected it on the cynical basis that any government would be tempted to build only the cheap ships and ‘defer’ the more expensive version.

The Type 23, ‘Duke’ Class

An outline Staff Target was issued in early 1981 for a light ASW frigate, Type 23.²⁸ This called for a very quiet ship, shaped to minimise Radar Echoing Area (REA), good endurance at moderate speeds, good seakeeping, a flight deck and hangar for the very large EH 101 helicopter²⁹ and all this for not more than £70 million at 1980 prices.³⁰ The size of the EH 101 (now Merlin) is often not appreciated; a comparison with a Second World War Swordfish is given in Chapter 11.

The electric cruising propulsion conceived for the Type 25 was adopted and after some thought it was decided that this plant would provide sufficient astern power.³¹ Two of the diesel generators stand on 01 deck for noise isolation. The electric motors were connected directly to the shaft, eliminating gearbox noise. This enabled fixed pitch propellers to be chosen, which it was believed would be quieter than a CP propeller.³² A very low shaft rotation speed was adopted, which made the noise performance at key speeds and frequencies virtually as good as a pumpjet, which would have been much more expensive. The plant (including the large, slow-running propeller) proved very economical, helping endurance, and it has been stated that the class are the world’s quietest surface ships. A complete set of the electrical plant, including two diesel generators, was tested on shore.

The Type 23 frigate Marlborough. The flat-sided funnel helps to reduce radar signature, as do the sloping sides of the hull and superstructure. (MoD)

The main parameters of the form were selected using Goddess programs and confirmed by model tests. The selected form had a low CP, a high CM and Cw with deep V sections forward to minimise slamming.³³ The V shape was continued above the waterline to resist pitching and the freeboard was slightly greater than in earlier classes. Very deep, though rather short, bilge keels were fitted, together with fins. Flared hull sides not only helped to reduce radar signature but increased stability if the ship sank deeper in the water due to weight growth or damage. Early reports from sea confirm their seakeeping ability.

The first study was for a 107m ship that exceeded the target price and had serious operational problems. There was no hangar and, unprotected, the helicopter would soon become non-operational; and it had no self-protection system. Desperate measures were taken to reduce cost, including elimination of one main engine!³⁴ Some economy in structural design was also agreed. The design was reconfigured at 115m with a single Sea Wolf system and a basic hangar, though the cost was over £70 million. This was submitted in early 1982 and approved complete with the second engine and a second Sea Wolf tracker. Ability to operate Sea King as well as EH 101 added a further 3m to the length and the extra space reduced congestion in the machinery and accommodation.

The lessons of the Falklands war led to further major changes. A 4.5in gun was added for shore bombardment and vertically-launched Sea Wolf was approved. The number of fire zones was increased from 3 to 5 with no ventilation crossing the boundaries. Cables passed through glands (expensive) rather than openings as in earlier classes. An extensive surveillance system was installed so that damage control would always know the state of ship systems. There was a great reduction in the extent of ship side and deckhead linings³⁵ as these can obstruct leak-stopping and fire-fighting. Many of these measures had both advantages and disadvantages and there was quite heated debate within the design organisation.

A major feature of the design was a small complement, which meant that many minor items of maintenance had to be done ashore on return rather than at sea. This led to much heart-searching on the reduction in the extent of linings which made it much more difficult to keep the ship clean – how do you balance ease of cleaning against easier damage control? The original complement was 167, increased to 185 when the Falklands additions lengthened the ship to 123m. If the length is determined by weapon and sensor arrangement of the upper deck, then crew are not expensive; conversely, if the ship has to be lengthened to get men in it, becomes very expensive – £80,000 per man. The loss of self-maintenance has caused problems in worldwide deployment, which the class was not designed for. Accommodation has been grouped in three blocks: officers in the superstructure, senior rates forward mostly on 2 deck, and junior rates aft. This grouping reduces the extent of services and aids privacy.

The hull structure is unusual for a warship: deck and bottom are of fairly conventional longitudinal structure but the sides are transversely framed. This has led to an increase of 40 tons in weight but a worthwhile reduction in cost. An incidental advantage is that there are fewer traps where water can lodge causing corrosion. The difficulty foreseen was the connection of the transverse and longitudinal sections. Full-scale sections were tested at NCRE, culminating in a large hull section being subjected to an underwater explosion in the HULVUL trials, where it performed well.

The first ship, Norfolk, was built before Yarrow’s reequipment was complete and unit weight was limited to 55 tonnes, with 35 per cent of man-hours achieved before launch, the cost of work alongside after launch being several times the cost of shop work. In later ships the structure was built in 60-tonne blocks that were then assembled into 400-tonne blocks which were largely outfitted in a module hall before being moved to the slip. The 60-tonne units can be rotated, permitting down-hand welding and, later, easier installation of electrical cables. As a result, launch displacement has increased by 35 per cent and 80 per cent of man-hours were before launch. Norfolk was ordered in October 1984 and delivered in November 1989. Since then eleven have been built by Yarrows and four by Swan Hunter. Building at a second yard meant the transfer of about 12,000 drawings on microfilm.³⁶

The ‘Short Fat Frigate’

During the early 1980s a number of claims were put forward by Thornycroft, Giles and Associates (TGA) for a frigate with a form derived from their successful motor launches. These claims were supported by an informal committee chaired by Lord Hill-Norton, summarised by them as:

It is claimed that a radical alternative in the shape of a short/fat form would provide very substantial advantages in building and maintenance costs, in construction time, and in simplicity of layout, with no operational penalties. Indeed it is further claimed that such vessels would be more stable, with better seakeeping and manoeuvring performance, more commodious between deck space and thus better accommodation, and that they would be able to carry a greater weapon outfit.

After a long campaign the government placed a contract for an independent review of frigate design by Lloyd’s Register. As part of this review TGA were contracted to design a ship incorporating their views but meeting the Staff Requirements for the Type 23 (‘Duke’) class (S102). This expensive review vindicated the official view in almost every aspect.³⁷

¹ The covering paper in DEFE 10/461 refers to actions long forgotten by most people – Palestine patrol, Cyprus, Icelandic ‘Cod War’, Malaysia, British Guyana, Bahamas, as well as disaster relief and salvage work.

² This paragraph is slightly adapted from NSR 7025, originally Secret, now DEFE 10/461 (PRO).

³ A very good paper on anti-FPB guns was later produced by ASWE during the design of the ‘Castle’ class. For a quick kill at 6000 yards, by far the best available (and the cheapest at £100,000) was the Centurion tank 105mm (also the basis for CFS 2). Unfortunately, the Staff ‘improved’ it to a new cost of £6 million, more than the then cost of the ship.

⁴ Later ships would have ‘Confessor’, NST 6522 (this became Sea Wolf).

⁵ It was recommended that all four diesels should not normally be used together due to the need for maintenance.

⁶ Later variants had the twin 4.5in Mark VI, presumably due to delays in the Mark VIII. The Mark VI had little anti-FPB capability and the Mark VIII was not brilliant.

⁷ Quoted in the author’s A Century of Naval Construction, p230. The original has not been located.

⁸ The author was running the specialist section covering hydrodynamic aspects and this paragraph is based on his memory.

⁹ This is a particularly difficult speed band for propellers. Very large cavitation bubbles form at the leading edge and collapse before the trailing edge with impact loading of about 100 tons/in². At higher speeds the bubbles collapse clear of the propeller.

¹⁰ The constructor on the propeller section at Haslar was a pessimist and held out for 20 minutes life for the Type 19’s propellers. Optimistically, I thought that we could repeat the 20-hour figure.

¹¹ Propeller changes with the ship afloat had been tried with fixed pitch propellers. With difficulty, it should have been possible to change CP propellers afloat.

¹² I am a great enthusiast for hovercraft in the right role.

¹³ D K Brown, Future British Surface Fleet (London 1991)

¹⁴ This project created much ill-feeling at the time, some of which has endured. The author has tried to be impartial in discussing the problems involved. The draft has been discussed with Peter Usher, who was in charge of the design and later managing director of Vosper Thornycroft, and most of his comments have been incorporated.

¹⁵ See Purvis’ comments on P J Usher & A L Dovey, ‘A Family of Warships’, Trans RINA (1989).

¹⁶ I am assured that Vosper Thornycroft never made such a claim.

¹⁷ The exact mechanism of the improvement is unclear: resistance of the hull is slightly reduced but the major effect is on propeller performance. The author had been involved in the success of a flap on the ‘Gay’ class fast attack craft (see Chapter 10 ) and spent about 20 years trying to get a flap on a frigate.

¹⁸ See D K Brown, A Century of Naval Construction, p258 for a summary of the reasons.

¹⁹ H L Lloyd, ‘The Type 2016 Fleet Escort Sonar’, Navy International (August 1979).

²⁰ It is often stated that they were not strong enough to carry the heavy winch. This seems unlikely though the array itself can impose severe loads when towing in a seaway.

²¹ Some reports say it was intended that up to twenty-six Type 22s would be built. This is a misinterpretation of normal and correct financial planning. It was normal to insert figures into a 10-year spending plan for so many frigates per period, and for financial planning it was assumed that they would be of the latest design.

²² N Friedman, World Naval Weapon Systems 1991/92 (Annapolis 1991), p531. There is even a photograph showing Outboard antennae on a Type 22.

²³ The cachet of RN service was important in export sales.

²⁴ D K Brown & D J Andrews, ‘Cheap warships are not simple’, SNAME symposium Ship Costs and Energy, New York 1987. We were often asked how big our relative contributions were and gave an agreed answer, A quarter each and the rest in discussion between us’.

²⁵ ADM 1/28609 (FRC/P63.16) (PRO).

²⁶ It is interesting that Ship Dept gave 20,000 as the maximum power on a single shaft. AEW Haslar, which designed the propellers, would have accepted much higher powers per shaft. Haslar was just beginning to feel confident with advanced propeller design.

²⁷ D K Brown, Future British Surface Fleet (London 1991).

²⁸ The type number 23 had been allocated to a big ASW frigate, which was never started. Hence the out-of-sequence Types 24 and 25.

²⁹ This should have read EHI 01 (European Helicopter Industries) but a typing error made it EH 101. A second error changed its name from Marlin to Merlin.

³⁰ Admiral Sir Lindsay Bryson, ‘The Procurement of a Warship’, Trans RINA (1985), p21. The discussion was wide ranging and, at times, acrimonious.

³¹ Less than recent COGOG ships but as much as a Leander.

³² I believed that a CP propeller could have been just as quiet at the light loading of the Type 23 propeller.

³³ See Glossary, roughly, fine ends, full amidships and with a fairly full waterplane.

³⁴ 1 suspect there was a touch of the reductio ad absurdum here.

³⁵ Generally allowed only for hygiene in galley and sick bay.

³⁶ D K Brown, ‘The Duke Class Frigates examined’, Warship Technology, Part I 1989 (3), Part II 1989 (4).

³⁷ Warship Hull Design Inquiry, HMSO 1988.