<%@LANGUAGE="JAVASCRIPT" CODEPAGE="CP_ACP"%> Genealogy


Genealogy

Any warship ends up being an amalgamation of compromises, apart from the obvious one: cost, speed, weight, weapons, there are the less obvious ones: how much storage for food, spares, fuel? How much space for living accomodation? What about redundant systems to allow for battle damage?

But there is one very big factor that is unique about a purpose designed Convoy Escort: It has no use whatsoever in Peace Time.

The RN recognised the problem. Between the wars the problem was addressed by up gunning the Flower Class Sloop design that had served so well in WW1, this allowed them to perform a peace time role as the guardians of the Empire, gunboats if you will.

But by the latter stages of WWII anti-submarine weaponry had become highly specialised, no more was it a case of providing a flat stern off which high explosive dustbins could be rolled. The Hedgehog and Squid fired forward into the sonar probing ahead, overcoming the perenial problem of Sonar being unable to hear past a ship's own engines and the "escape zone" when the ship passed over a contact before engaging with depth charges.

Although it would flirt briefly with the concept of the Escort Destroyer again with the Type 16 the RN made the firm distinction that the Destroyer and the Frigate served different roles and could not be combined, to reinforce it the term Frigate which had been coined by the Canadians to describe twin screw corvettes was now applied to any and all ships whose primary task was to provide Escort duties to the Fleet or Merchant Ships.

Post war design of the new Frigate saw the Type 15 bring together the weapon fit and layout that would become the mainstay of the RN Frigates for most of the remainder of the century. First Squid, but now mounted aft to fire over the ship, which solved a number of problems, mainly allowing the heavy weapon and loading gear to be mounted low without worrying about heavy weather. Then when Limbo became available this was fitted, this hugely increased the tactical ability of the ASW ship since now it was free to manouvre and engage at the same time as the Limbo mortar could fire in any direction.

A mid calibre gun was provided to engage a submarine brought to the surface and - together with rapid fire 40mm radar guided guns - provide air defence. Homing torpedoes were also attempted, but the RN would never properly develop one and it would eventualy buy from the Americans until the Stingray made its long awaited debut.

Less obvious was what the Type 15 had inside: an Operations Room from which battles would be fought, no more would the exposed Bridge be the nerve centre of battle. Sonar and Radar had developed from a small screen in a dark cupboard to banks of large screens with elaborate electronics.


The main problem with an Escort ship is what do you do with them in peacetime to justify their existance and cost. The RN and in this case the RAN were able to utilise a limited number of Escorts as Empire police boats. This is a Grimsby Class Sloop, based on the Flower Sloop that was the premier Escort ship for the Empire during WW1. Commissioned in 1936 she is the HMAS Yarra which took on three Japanese Cruisers and two Destroyers on 4 March 1942 in order to give the convoy she was escorting time to scatter, only 13 of her crew of 151 survived.

HMS Tenacious, the Type 16 was the RNs last uneasy flirtation with the Escort Destroyer.

HMS Undaunted, the Type 16 Frigates were the first of a new generation single purpose fast submarine killer. But although the concept was good and the platform excellent they were intended to act as part of an integrated Fleet, cut backs would soon make the concept of the dedicated anti-submarine escort unworkable in the RN.

The war had taught the value of pre-fabrication and the avoidance of depending on specialist yards that could be bombed. In the event all the post war Escorts would be built in RN yards to try and ensure their continued existance. The hulls would be relatively broad compared to a Destroyer to allow for the increase in equipment and to generate the power for them, accomodation had become a major factor too, despite the fact that the RN was shrinking daily it was struggling to find and keep enough manpower to crew it's ships, and the greatest single factor was accomodation, many men had seen how the Americans cared for the welfare of their crews and the demand was for the RN to do the same.

The plan to provide a fast Anti-Submarine ship for Fleet work and a long range one for convoy work was an early victim of economics and the two were combined into the Type 12. Although the aircraft defence ships went ahead as planned the Type 61 & 41 showed again that a dedicated Convoy Escort had problems finding a place in a peacetime Navy. The design was axed. The Type 12(I) was proving a very versatile ship, it was sound in the heaviest of seas, was a superlative submarine hunter and relatively cheap. Although the 4.5" Mk6 was not turning out to be a very good AA weapon it was a good - if lightweight - provider of Naval Gunfire Support (NGS).

The removal of the heavy STAAG system and the defunct anti-submarine torpedo tubes meant there was top weight to be played with on the Type 12(I), enough to allow the provision of a 965 air warning radar, albeit with the single AKE aerial. This did not give the Type 12(M) true aircraft direction ability since it lacked the 3 dee (height, range and bearing) of the true aircraft direction radar, but it did allow the ship to act as a radar picket.

A more radical change was the provision of the Wasp helicopter, then still in development. This needed more top weight in the form of a hanger and the loss of one of the Limbo Mortars, to compensate for the extra weight some fairly radical changes had to be made to the location of the machinary inside the ship. Like all compromises things were lost. The Limbo was most effective fired in pairs to put a pattern above and below a submarine, the single AKE antenna left gaps in the vertical coverage which an enemy aircraft could exploit. Range was poor compared to the diesel powered ships, but still enough for the key requirement: enough to get across the Atlantic.

But those issues aside in the Type 12(M) Leander the RN had produced a superb work horse. The Type 12(I) Rothesay ships would be refitted to bring them close to the Leander capability, though the cost of re-positioning the machinary was considered too high so the ships did not get the extra room of the superstructure and so limited them to less equipment than the Leander, in particular the 965 and a more comprehensive Electronic Warfare fit.

In the 70's there was a shortfall of Frigate numbers even by the ever reducing allowed amount. The Type 22 Frigate was in development but it depended on Seawolf which was years behind schedule. Tenders were invited from civilian builders and a Vosper Thornycroft design chosen, the type was based on already proven designs and would replace the older Type 12 Frigates and the Type 41, 61 and 81. Very much a platform for then new Lynx helicopter the ship was gas turbine powered and very fast, but proved vulnerable to hull stress.

The Type 22 eventualy entered service, but it was a poor successor to the Leander, very large and poorly armed, the ship was hailed as the first all missile ship which quickly showed it's draw backs and 40mm guns were fitted. Although the Seawolf system proved as good as was hoped barring some problems with the software which meant it had trouble assigning priority to multiple targets, but the ship itself was too specialised a sub hunter to be much use for anything else. The Batch 2 introduced towed array which at least justified the size of the ship as it takes a strong stable platform to tow miles of electronic cable. The Batch 2's were also built as surveillance ships with the ability to monitor radio traffic on land.

The Batch 3 were built after the Falklands and reversed the trend to down arm ships, to some degree. Armed with Harpoon anti-shipping missiles, a gun and Goalkeeper CIWS as well as Seawolf they immediatly established themselves as excellent force leaders with ample Ops Room capability and additional space. However although fitted for four twin 30mm canons the rot set early and the ships were only equipped with two and no 20mm cannons were fitted.

The Type 23 finaly produced a capable ship in a comparable size to the Leander. The ships used a combination of gas and electric engines which allowed them to sprint at need and to go as silent, if not more so, than a submarine since the diesels to power the engines were fitted above the waterline. The design though, was a radical change to the original concept which was for a cheap towed array and helicopter platform.

The Leander Class remained in service to see the new frigates in, and out again in some cases! Many of the new weapons on these ships were also fitted to Leanders: Seawolf, Exocet, Lynx STWS homing torpedoes. The sensors too, one of the last changes made to Leanders was to equip some with towed array, though the strain hastened the end of those ships they lasted long enough until the new ships came on line.

1915
to
1918

Flower Class Sloop
Although not designed as Escort Ships the Flower Class Sloop became the primary Convoy Escort of WW1. Designed as Fleet Minesweepers they had good sea keeping and could operate at slow convoy speeds better than a Destroyer. They proved even better than purpose built Escorts such as the P type coastal destroyer and the 24 Class.

1928
to
1945

Post WW1 Sloops
Between the wars the Escort Ship was dropped in favour or returning to the Fleet Minesweeper, a number of classes were built, most developing on the Flower Sloop design. The class culminated in the Black Swan type pictured here, but their primary armament was guns with depth charges only a secondary, most being fitted for but not with prior to the outbreak of WWII. They were primarilly used as hunter killers in U-Boat transit areas where ships were liable to air attack from the Mainland.

1939
to
1942
Hunt Class Destroyer
The Hunts were designed as Second Rate Destroyers which could double as Fleet or Merchant Escorts, primary armament was still guns. Most served in home waters or the Mediterranean where the primary threat was aircraft attack and surface raiders. Poor range and sea keeping made them unsuitable for Atlantic Convoy defence.
1941
to
1944

Flower Class Corvette
The Flower Class Corvette is the best known Escort Ship of all time, purpose built for the task and based on merchant design to enable it to be constructed in merchant ship yards. Designed as an all weather depth charge platform they carried only rudimentary surface and AA weapons. Although intended to act as coastal escorts they were actualy used in both the Atlantic Theatre and the Russian Convoys.

1942
to
1943
Captain Class Frigate
Designed and built by the Americans to a British specification the Captains were classed as Destroyer Escorts by the Americans and saw extensive service in the US Fleet in the Pacific. The British variant omitted the torpedoes in favour of additional depth charges. With the entry of America into the war most Captains were sent to the US Fleet instead of exported to Britain
1943
to
1944
River Class Frigate
Designed as an improved Flower Class Corvette the River Class were highly succesful Convoy Escorts with long range, heavy depth charge load and good sea keeping. Built in both Canada and Britain they became the mainstay of the Atlantic Escorts in the latter stages of the war.
1943
to
1944
Colony Class Frigate
American built ship based on River Class Frigates loaned to the USN after their entry into the war. Although outmoded by the time they were delivered to the UK the Admiralty knew from intelligence that the German Navy intended a new and greater offensive in the Atlantic to prevent the build up to D Day and needed every ship. However the new class submarines that were to spearhead the campaign were delayed in production and never became the threat they had promised to be.
1944 Castle Class Corvette
Designed as an improved Flower Class Corvette with a stregnthened bow to mount the Squid Anti Submarine Mortar and longer to accomodate the sonars and improve sea keeping. However the Castle used the same power plan as the Flower and being larger she was hopelessly under powered. Helmsmen found it difficult to hold the ship in heavy seas and at low revs they lacked manouvering ability, crucial for the Squid which could not be aimed, the ship had to turn onto the target.
1944 Loch Class Frigate
The Loch Class were the culmination of Anti Submarine Escort Design in WWII, designed around the Squid Mortar which fired ahead of the ship into the beam of the sonar, they made an immediate impact. But even as they were being built the invasion of France knocked out the forward U-Boat bases and the battle of the Atlantic was virtualy over. Those Lochs still under construction were converted on the slipways into the Bay Class Frigate.
 1945

Bay Class Frigate
Modified Loch Class to convert to Anti Aircraft. Carried heavier AA weaponry and radar director. Still carried a hedgehog and depth charges but primary role was now AA, intended to give support to the D Day landings and for the Pacific theatre were the main threat was from air attack. Use of pre-fabrication and the ability to use a common hull for different variants were features that ensured much of the Bay and Loch classes would influence post war Escort design.

1951
to
1956
  Type 15 Frigate
1950
to
1954
Type 16 Frigate
During the early 50's the RN experimented with two fast Frigate designs based on existing Destroyer hulls. The Type 16 was more along the lines of the Destroyer Escort, comparable to some US designs. The design was cheaper than the Type 15, requiring less work to complete. But it was soon apparent that "wind in the hair, shoot from the hip" days of submarine hunting were gone, the Type 15 with Operations Room and increased space for equipment was far superior.
1957
to
1960

Type 61 Cathedral Class
Intended to be a common hull pre-fabricated design the sister classes were each to have a dedicated role. The Type 61 was a convoy air defence frigate, her primary role was to vector land or carrier based aircraft against enemy aircraft. Entered service late due to delays in equipping them, the first of Class was actualy laid down in 1952.

1957
to
1959
Type 41 Cat Class
Virtualy identical to the Type 61 but with the aft radar mast omitted in favour of a second turret to give air defence. The modification was probably brought about because of the problems getting the Type 61 into commission. Like the 61 designed for long range Convoy Escort and diesel powered.
1954
to
1958
Type 12 Whitby Class
Although intended to share the same hull as the Type 41 & 61 the requirement for higher speed for the ship to operate as a Fleet Anti-Submarine Escort or Hunter Killer meant that the hull had to be lengthened to accomodate the steam plant chosen, diesels were not able to generate the required speed of 30 knots. Like the sister classes designed to be pre-fabricated and for assembly in non specialised yards in the event of war. Built around the improved Squid, the 360 degree trainable Limbo Mortar.
1956
to
1958
Type 14 Blackwood Class Frigate
Technicaly actualy a corvette as the definition of a Frigate in WWII had been a twin screw ship and the Type 14 had only one. Intended to form squadrons with a Type 12 Whitby as Squadron Leader for three Type 14s. Armed with two Limbos, Anti-Submarine torpedoes and 40mm Bofors for air defence. The building program was cancelled after 12 ships due to the restriction of Fleet numbers, with less ships allowed the Type 14 became problamatic as it could serve in no other role.
1959
to
1962
Type 81 Tribal Class Sloop
Although redesignated Frigates these ships were designed as Sloops to replace the Black Swan Sloops in their peace time colonial roles. Included for information but they were never intended as Escort Ships but had an admirable multi-role capability with a Limbo mortar, helicopter, anti aircraft missiles and guns. Like the Black Swans though they would have operated as Escort Ships in the event of war.
1960
to
1961
Type 12 (Modified) Rothesay Class Frigate
As built the Type 12(M) were almost identical to the original Type 12. The main difference was the provision of air conditioning. Although designed for Atlantic Convoy duties the Type 12 had found itself deployed to tropical waters as the Sloops which traditionaly carried out colonial duties were scrapped. In such conditions the lack of air conditioning caused problems with the ship's electronic systems over heating. It is a phallacy to suppose the air conditioning was provided for the crew as some claim. Shown here is the mid life modernisation of the ship which brought it close to the fit of the Type 12(M) Leander Class.
1963
to
1973
Type 12 (Improved) Leander Class Frigate
The first 12(I) Frigates were actualy laid down as Type 12(I) Rothesay Class and were converted during build. Further cut backs meant the RN could not afford to operate ships in dedicated roles and new nuclear powered submarines promised to outrun the fastest surface ship. The decision was taken to combine the air defence role with the anti submarine role as had been done on the Tribal Type 81. The Tribal itself was not used as it fell short of the 30 knots required to allow the ship to operate both as a Convoy and Fleet Escort
1974
to
1978
Type 21 Amazon Class Frigate
The Type 21 was an attempt to provide a good all rounder to replace the Type 81 Tribal ships, listed originaly as "Patrol Frigates" they were entirely gas turbine propelled and carried the heavier Lynx helicopter. Problems however at high speed resulted in structural damage and the ships had to be governed to a lower speed and fitted with trim tabs to prevent the stern digging in too deep. They were also very heavy on fuel.
1979
to
1990

Type 22 Frigate
Built in 3 batches some confusion reigns over the design of this ship. Although at the time believed to be a replacement for the Leander there are several Hansard references which state the Type 23 was the replacement for the Leander. This could of course be political hindsight as the Type 22, with the exception of the Batch 3, proved a ridiculous bloated under-armed concept and both early batches were quietly scuttled or sold mid life. Naming convention was lost, the first batch were Battle Class names, the second batch a mix of things begining with "B" then London, then named for two ships lost in the Falklands, the third batch were towns towns or counties begining with "C".

 

1990
to
2002

Type 23 Frigate Duke Class
Although the original numbers have been cut the Type 23 has become the true replacement for the Leander, but it was only through the Falklands war, the original design of the ship would have made her an unarmed towed array tug which could operate a Helicopter but not store it. The ships were intended to work in task groups of four with an RFA equipped with Seawolf and a large hanger to accomodate the helicopters. The concept of an unarmed ship having to rely on a consort with short range missiles for defence simply beggers my imagination! In the event the Type 23 is a superbly equipped all rounder, although cut backs have also meant they operate the Lynx helicopter instead of the designed for Merlin.