1930s British Sanity Options (Economy, Navy, Airforce and Army)

[NOMISYRRUC]

Minor War Vessels - Ships Ordered to 31st March 1940 IOTL
Summary

The following minor war vessels were ordered by the Admiralty between the wars and in the War Emergency Programme, which for the purposes of this thread includes the minor war vessels ordered between the outbreak of World War II and 31st March 1940.

These figures don't include the ships ordered for the navies of the Dominions and India before the war or in their mobilisation programmes. These includes 2 escort sloops built in Australia for the RAN and 2 escort sloops built in Britain for the RIN. They increased the total to 59 new minor war vessels consisting of 32 escort sloops, 6 patrol sloops and 21 minesweeping sloops.

There were also 37 minor war vessels that had been built in the First World War, which brought the total to 96 consisting of 41 escort sloops (3 RAN and 5 RIN), 8 patrol sloops (one RIN) and 47 minesweeping sloops.

The designations are from Lenton and Colledge. According to them:

An escort sloop was capable of ocean A/S and AA duties;​

A patrol sloop was capable of coastal A/S duties;​

A minesweeping sloop was capable of ocean and coastal M/S duties and could be pressed into performing the duties of an escort sloop or patrol sloop if so required.​

Escort Destroyers (20 building or on order)

The ships on order were the first 20 Hunt class that had been ordered in the 1939-40 Estimates and would be completed between March 1940 and February 1941. Another 36 would be ordered in the War Emergency Programme and be completed between December 1940 and July 1942. The last 30 Hunt class would be ordered in the 1940-41 programme and completed between December 1941 and May 1943.

Jane's Fighting Ships included these ships in the Escort Vessels section. It also had the flotilla leader Wallace and the V&W class destroyers that had been given the W-AIR refit in this section and said that they were ex-destroyers.

Escort Sloops (41 completed (34 RN, 3 RAN and 6 RIN) and 8 building or on order)

The 9 old ships consisted 5 Flower class and 4 "24" class built in the First World War (one RAN and 4 RIN). This included the Flower class sloop HMIS Pansy, requisitioned by the RIN from the Calcutta Port Authority on 2 September 1939.

The Royal Navy had 28 new ships of the Bridgewater to Egret class completed 1929-39. Under construction were 4 Black Swan class which would be completed 1939-41. According to Jane's Fighting Ships 1939 many of the 14 ships of Bridgewater to Falmouth classes were to be rearmed with six 4" in three twin mountings and all 8 Grimsby class were to be rearmed with six 4" in three twin mountings as opportunities occured.

The RAN had 2 Grimsby class built in Australian yards and completed 1935-36. Another 2 Grimsby class which would be completed in 1940 were under construction in Australia for the RAN.

The RIN had one Folkestone and one Grimsby class built in the UK and completed 1930-35. The Government of India had ordered 2 Black Swan class from British yards which would be completed in 1941.

None of the Royal Navies included escort sloops in their mobilisation programmes. The Admiralty did order 34 Black Swan class from April 1940 onwards (18 in 1940-41, 11 in 1941-42 and 5 in 1944-45) but 7 were cancelled at the end of the war and the other 29 were completed 1942-46. The Government of India ordered 4 Black Swan class from British yards in pairs in 1940 and 1942 which were completed in 1943.

8 Patrol Sloops (8 completed (7 RN and one RIN), 3 building and 60 on order)

The 8 patrol sloops consisted of HMIS Pathan (ex-PC.69) & PC.74 built in World War One and 6 Kingfisher class completed 1935-38.

Under construction were 3 Kingfisher class ordered in the 1937-38 Estimates that would be completed before the end of 1939.

60 Flower class (including 4 for France) were ordered in July and August 1939 in a supplement to the 1939-40 Estimates. They would be completed between April 1940 and July 1941.

60 Flower class were ordered in the War Emergency Programme. 50 were ordered from British yards and completed between July 1940 and July 1942. 10 were ordered from Canadian yards and completed between October 1940 and May 1941.

The Dominion of Canada ordered 64 Flower class from Canadian yards for the Royal Canadian Navy as part of its mobilisation programme. They were completed between November 1940 and April 1942.

Jane's Fighting Ships 1939 lists the Flower class as patrol vessels in the recent naval programmes section, but the section on ships under construction or on order says they were trawlers.

Minesweeping Sloops (47 completed (all RN) and 20 building or on order)

The 47 minesweeping sloops consisted of 26 Hunt class built in the First World War and 21 Halcyon class completed 1934-39.

45 Bangor class were built in British yards as follows:

• 20 ordered in the 1939-40 Programme and completed between September 1940 and March 1942. 4 had diesels, 6 had reciprocating engines and 10 had turbines;
• 22 ordered in the War Emergency Programme and completed between February 1941 and February 1943. 16 had reciprocating engines and 6 had turbines. They were all ordered for the Royal Navy, but 6 were commissioned into the RIN;
• 3 with reciprocating engines were ordered in the 1940-41 Programme and completed between March 1942 and June 1942. They were ordered for the Royal Navy, but were commissioned into the RIN.

The British 1940-41 Programme also included:

• 4 Bangors with reciprocating engines ordered from shipyards in Hong Kong that were captured by the Japanese before they were completed, and;
• 12 Bangors ordered from Canadian shipyards that were completed between February 1942 and August 1942. 6 had reciprocating engines and 6 had VTE engines. They were ordered for the Royal Navy, but 6 were commissioned into the RCN.

18 Bangors were built in Canadian yards for the Royal Canadian Navy and completed between April 1941 and December 1941 as part of its mobilisation programme. The next 30 were completed between October 1941 and December 1942. 10 of the 48 Bangors build in Canada to Canadian account had diesel engines and the other 38 had reciprocating or VTE engines.

The Government of India ordered 4 Bangor class for the RIN from Indian yards. That is 2 in 1940 that were completed in 1942-43 and 2 in 1942 that were completed in 1945.

That made a grand total of 113 orders for Bangor class minesweepers (45 UK, 60 Canada, 4 India and 4 Hong Kong). 109 were built and completed between September 1940 and 1945. The 45 British built ships included 4 with diesels, 25 with reciprocating engines and 16 with turbines. The 60 Canadian built ships included 10 with diesels, 6 with reciprocating engines and 44 with VTE engines. All the ships built in India and Hong Kong had reciprocating engines.

Meanwhile the Australian Government ordered 4 Bathurst class minesweepers as part of its mobilisation programme. These were the first of an eventual total of 60 ships that would be completed between December 1940 and May 1944.

 

[Masked Grizzly]

Apparently in late-1937 there were plans for a Second Works Programme by the London Passenger Transport Board (LPTB), due to the original New Works Programme needing more money (and the possible addition of new tube extensions/lines) that had it been approved and had Britain avoided WW2 was envisaged to be completed by 1950. - https://www.londonreconnections.com/2020/lr-answers-the-post-war-second-works-programme/

It was an ambitious 10-year programme was foreseen in a detailed paper presented by JP Thomas, the London Passenger Transport Board General Manager (Railways), to the 4th November 1937 Second Annual Conference of the Members and Officers of London Transport.

While it seems no PDFs exist on the specifics let alone on the additional new tube extensions over the original New Works Programme, it would appear based on some of the information so far that aspects of it would later find their way into the post-war 1946 London Railway Plan (that was brought to life on an ATL 1946 London Tube Map).

 

[ArtosStark]

I have been digging into British Radar Development lately. It seems it is less a case of finding POD's as it is of figuring out how early the electronics were available to make them work without getting a degree in the subject.

However, here are a few POD's for your enjoyment:
A guy named L.S Alder, who was a scientist at the Royal Navy Signal School, took out a patent in 1928 for what was basically radar. To quote "The Development of Radar Equipments for the Royal Navy 1935-45" (Which I am saving up to buy but have been able to preview some of)Alder "originated a provisional Patent Specification dated 1 March 1928, which quite precisely presaged radiolocation (Provisional Specification No. 6433/28). The following is an extract:

• Improvements in and relating to methods and means for determining positions, directions, or distances of objects by wireless waves, applicable to navigation and for the location of dangerous objects, or of enemy craft.
• Lodged by we, James Sacheverell Constable Salmond, Captain, Royal Navy, and Leonard Stanley Batar Alder. MSc, both of HM Signal School, Royal Naval Barracks, Portsmouth, Hampshire, both British Subjects,
• The invention relates to methods and means for the employment of the reflection, scattering, or re-radiation of wireless waves by objects as a means of detecting the presence of such objects. According to this invention, apparatus which may be placed on land or in a ship or in aircraft may be employed to generate wireless waves and to observe or detect their reflection, scattering or re-radiation from a surrounding object or objects, or a nearby object such as shipping, icebergs, natural land features, or the surface of land or sea below an aircraft, or from suitable reflectors constructed for the purpose in known positions, as, for example, at points dangerous to shipping, the entrances to harbours, or at aerodromes and landing places for aircraft, ect."

This was never followed up on, and even the request to apply for patent was refused by the Admiralty. When the document was sent to the Directorate of Scientific Research, it was "rejected by the Patents Section without even consulting the Director, or his scientific staff".

To be fair, it seems unlikely the technology of the day would have supported a viable Radar system at the time anyway, but it is still an interesting tidbit.

Next, once again from “Developments of Radar Equipment's for the Royal Navy 1935-45”, in the period after the first demonstration of Radar In 1935 HM Signal School was told to develop it themselves, but was given little priority in doing so. The head of research apparently thought that the technology needed to show itself useful before he asked the Admiralty for more funding. He later said he thought this was a mistake and in 1937 it was given its own department and top priority. More scientists recruited and more resources allocated and the systems were developed fairly quickly. For example, the experimental 79X radar was in development and small scale testing for over 2 years before the change up in 1937. After it 79Y was developed and in large scale production in a year and 79Z was in testing. Had this change happened earlier, in addition to C.E Horton being put in charge earlier, then it seems likely that RN ships would have entered the war with a reliable air search radar (279 or 281) a 50 cm low angle radar (which both CHL and ASV Mk. 1 could also have used) and a gunnery radar.

And this would have dovetailed nicely with my final Navy Radar POD. In between 1935 and the reorganization in 1937 A.B Woods, who was a scientist at HM Signal School at the time, knew of the trouble they were having getting 23 cm radar to work with a split anode magnetron. He proposed two designs for a multiple anode (cavity) magnetron. One of which was actually very similar to what was later developed by Randall and Boot in 1940. But the idea was "received very dubiously by the Chief Scientist" and he was told that the Valve department was busy building valves for their current Radar work. Wood left the Signal School just as Horton was being put in charge of Radar research. Had this been followed up on, it seems likely that Centimetric radar was possible before the war began, at least in development. Everything else was in place, as far as I can tell, except for the magnetron, without which it was impossible.

And, turning to the OTL development of Radar, it is important to note that all the scientific pieces for Chain Home were in place in 1931. The Meteorological Office had been tracking storms with direction finding equipment (tracking the radio signal given off by lighting) since 1922. Around the same time Edward Appleton had shot a radio signal at the sky and measured the changes in wavelength to determine the distance to the ionosphere. Watson-Watt was involved with or connected to both these teams (he apparently coined the term "ionosphere") and in 1927 he became head of the Radio Research Station, run by the National Physical Laboratory. He advocated for taking a greater role in the development of technology rather than the pure research directive they then held. In 1931 the RRS had found that aircraft, flying near a transmitter interfered with the radio signal. All this together would have allowed them to build a system that could locate the bearing of an aircraft from a radar station. The only thing missing was using pulsed waves for range finding. In 1924 American scientists had replicated Appleton's experiment with pulsed waves instead of changes in wavelength. This had been noted by others in the field and in 1931 two scientists (who would later develop Radar systems for the British Army) created a prototype system to detect the range to something with pulsed waves while working at the Signals Experimental Establishment. The War Office wasn't much interested and the knowledge of it did not become commonplace. If a Central organization had existed in this period, perhaps from the famous case of King George V's comment at his ASDIC briefing, then it is conceivable that a radar system would have been workable in 1931, with improvements to follow with the pace of electronics.

 

[PMN1]

Its not just radar though, its having the reporting system to use it properly, other countries had radar but lagged on the reporting system to use it effectively.

 

[ArtosStark]

True. But Dowding would still have been the Air Member for Supply and Research during this time (he started 1930) and unless something changes, he will still be head of Fighter Command in 1936, so it seems likely that the Dowding system would be in place even with a more developed radar system. And if you mean a system of the operator being able to interpret what the Radar is doing, CRT’s were available from 1932 and used commercially from 1934. The big driver for government funding to a radar system is still likely to be the RAF exercise in 1934 that had fighters unable to intercept the bombers. So I think CRTs are still likely to be used as much as they were in OTL just with a more refined system architecture.

 

[sonofpegasus]

The roots of British fighter control go all the way back to 1917, when the first organised air defence system was set up under General Ashmore. Dowding organised the marriage of a slew of new technologies with a proven system and oversaw the creation of the worlds first radar based air defense system. Many countries were developing radars of their own in the mid 1930's so whilst Great Britain did not invent radar the United Kingdom was the first to develop and field a viable radar based air defense system.

 

[NOMISYRRUC]

Minor War Vessels - ITTL
Part 1 - Ships Ordered 1st April 1927 to 31st March 1939

The Admiralty's requirements for minor war vessels would have been exactly the same as OTL. However, the number of ships ordered between the 1927-28 and 1937-38 Estimates would be exactly the same as OTL. This is in spite of the huge increase in the number required between 1934 and 1938.

There are two reasons why I think this.

Firstly the Admiralty would spend most of the extra money that it was given between 1929 and 1939 ITTL on other things. That is not cutting the Royal Navy's personnel strength by 10% in the first half of the 1930s, modernising the capital ships more thoroughly than OTL, the 3 extra aircraft carriers, the extra cruisers, the extra destroyers, and the Admiralty's contribution to the cost of maintaining a larger Fleet Air Arm of the Royal Air Force.

Secondly the Admiralty didn't need to build more sloops in peacetime because the First London Treaty and British Government allowed the British Commonwealth to have more destroyers. That is the tonnage quota of the TTL Treaty was a third larger than OTL's and the Government allowed the Admiralty to built 99 destroyers in the 6 financial years 1929-30 to 1934-35 ITTL instead of the 50 that were built IOTL. 236 destroyers were available at the outbreak of World War II ITTL instead of 192 or put another way 27 flotillas worth instead of 22, which is an increase of about 23% and all the extra destroyers were used for local defence and trade protection.

The Admiralty will order 11 sloops in the 1938-39 Estimates instead of none. AFAIK none were ordered in that financial year IOTL because of the "rationing" of new construction in 1938-39 and 1939-40 made necessary by the economic problems that rearmament had created. However, I have already explained that the TTL Rearmament Programme didn't create any economic problems because of the extra production capacity that was built up/retained between 1929 and 1936 so there was no need build fewer ships than planned.

None of the 11 sloops ordered in the 1938-39 Estimates were completed before September 1939. Therefore, the British Empire and Commonwealth (BEC) still had 96 sloops of all types (85 RN, 3 RAN and 7 RIN). However, there were some qualitative changes. That is there were 41 escort, 2 patrol and 53 minesweeping sloops instead of 41 escort, 8 patrol and 47 minesweeping sloops.

The 41 escort sloops in the (34 RN, 3 RAN and 6 RIN) consisted of 9 old and 32 new ships.

There were still 8 ships under construction or on order (4 RN, 2 RAN and 2 RIN) but 4 of them would be competed in 1940 instead of 1941. This is because the 4 Black Swan class escort sloops ordered for the RN and RIN in the OTL 1939-40 Estimates were brought forward to 1938-39 ITTL.

HMS Erne was completed in April 1940 instead of April 1941​

HMS Ibis was completed in August 1940 instead of August 1941​

HMIS Sutlej was completed in April 1940 instead of April 1941​

HMIS Jumna was completed in May 1940 instead of May 1941.​

They were also launched a year earlier, which allowed the next ships to be built on their slipways to be laid down a year earlier too, and so on and so on.

All 32 of the new escort sloops (28 RN, 2 RAN and 2 RIN) had been completed with six or eight 4" in twin HA mountings and a HACS or had been rearmed with them before September 1939. The pair of Grimsby class sloops being built in Australia would also be completed with this armament. This was an important qualitative improvement because only 5 of the RNs ships (2 Bittern class and 3 Egret class) had this armament IOTL.

Two things made this possible. First the extra cruisers and destroyers built between 1929 and 1936 ITTL increased the armaments industry's capacity to make guns in the 4" to 4.7" class along with their mountings and fire control equipment. Second none of the old destroyers had the W-Air refit ITTL, which allowed the twin 4" gun mountings and HACS fire control systems to be fitted to some of the sloops.

There were only 2 patrol and 53 minesweeping sloops at the outbreak of war ITTL instead of the 8 and 47 that existed IOTL. That is 6 Halcyon class were built instead of the first 6 Kingfisher class patrol sloops. IOTL 3 Kingfisher class ordered in the 1937-38 Estimates were completed between September and November 1939. ITTL 3 Halcyon class minesweepers were built in their place. 9 Halcyons were ordered in the 1938-39 Estimates were completed in the first half of 1940.

The 30 ships of the Halcyons and Kingfishers built IOTL included 23 with turbine machinery and 7 with reciprocating engines, but all 39 ships built ITTL had turbines.

The 60 ships ordered by the Admiralty between 1927-28 and 1938-39 IOTL were as follows:

In addition were the 4 escort sloops ordered by the Commonwealth of Australia for the RAN and 2 escort sloops ordered by the Government of India from British yards for the RIN. 2 of the 4 RAN ships and both RIN ships had been completed by September 1939.

The 71 ships ordered by the Admiralty between 1927-28 and 1938-39 ITTL were as follows:

In addition were the 4 escort sloops ordered by the Commonwealth of Australia for the RAN and 4 escort sloops ordered by the Government of India from British yards for the RIN. 2 RAN and 2 RIN ships had been completed by September 1939.

 

[NOMISYRRUC]

Minor War Vessels - ITTL
Part 2 - Mobilisation and War Construction
The Situation in September 1939

As explained in earlier posts the Royal Navies of the British Empire and Commonwealth (BEC) had 96 sloops of all kinds in service at the outbreak of World War II in both timelines, but that there were 41 escort, 2 patrol and 53 minesweeping sloops ITTL instead of the 41 escort, 8 patrol and 47 minesweeping sloops of OTL. This was because 6 additional Halcyon class minesweeping sloops were built ITTL instead of the 6 Kingfisher class built IOTL.

However, the major qualitative improvement was that all 32 of the new escorts sloops (28 RN, 2 RAN and 2 RIN) had been completed with a main armament of six or eight 4" guns in twin HA mountings and a HACS or had been refitted to this standard between 1936 and 1939. This was a great improvement over OTL because only 5 of 32 new escort sloops had this armament.

Uncompleted New Construction Ordered Before 31st March 1939

IOTL 2 Black Swan class escort sloops and 3 Kingfisher class patrol sloops ordered for the Royal Navy in the 1937-38 Estimates were completed between September 1939 and January 1940. 3 Halcyon class minesweeping sloops were ordered instead of the Kingfishers ITTL and they took the same length of time to build.

No sloops were ordered for the RN and RIN in the financial year 1938-39 IOTL. However, ITTL the British ordered 2 Black Swans and 9 Halcyons and the Government of India ordered 2 Black Swans from British yards for the RIN. The 9 Halcyons were completed in the first half of 1940. The 4 Black Swans were the 4 ships ordered in the 1939-40 financial year IOTL brought forward by one year, which meant they were completed between April and August 1940 ITTL instead of between April and August 1941 IOTL.

2 Grimsby class escort sloops were building in Australia for the RAN in both timelines. They were completed in April and August 1940 in both timelines, but ITTL they were armed with six 4" guns in three twin HA mountings and a HACS.

Ships Ordered 1st April 1939 to 31st March 1940

This period encompasses the ships ordered in the 1939-40 Estimates and War Emergency Programme.

The Admiralty ordered 240 ships IOTL. That is 56 Hunt class escort destroyers, 2 Black Swan class escort sloops, 120 Flower class corvettes (including 4 originally ordered by the French Navy) and 42 Bangor class minesweeping sloops. This included 10 Flower class corvettes that were ordered from Canadian yards. The Government of India ordered 2 Black Swan class for the RIN from British yards.

The Admiralty ordered 238 ships ITTL. That is 56 Hunt class escort destroyers, 120 Loch class frigates (including 4 originally ordered by the French Navy) and 42 Halcyon class minesweeping sloops. All the ships ordered ITTL were built in British shipyards.

Building Capacity

IOTL a total of 119 destroyers and 62 sloops of all kinds were ordered from British yards for the Royal Navies between 1st April 1927 and 31st March 1939. ITTL the totals were 187 destroyers and 75 sloops. The combined increase was 81 ships or 45%. This increased Britain's the capacity to build destroyer type hulls, machinery, armaments and fire control equipment.

However, the most important changes had taken place in the merchant shipbuilding yards. The TTL scrap and build scheme was designed to encourage the ship owners to replace their existing ships that were predominately fitted with reciprocating machinery with larger ships propelled by turbine machinery. Meanwhile, the shipbuilders were encouraged to offer standard designs that could be mass produce and to increase the length of their slipways so they could build larger ships.

The Escort Destroyer Programme

86 Hunt class destroyers were built in both timelines. That is 20 in the 1939-40 Estimates, 36 in the War Emergency Programme and 30 in the 1940-41 Estimates. 19 were completed in 1940, 25 were completed in 1941, 39 were completed in 1942 and 3 were completed in 1943. There were no qualitative improvements.

The Escort Sloop Programme

As already explained last of the 6 Black Swan class sloops ordered to 31st March 1939 was completed in August 1940. This ship was HMS Ibis and ITTL she was the last escort sloop to be built in a British shipyard. This was because 35 Bay class AA frigates were built instead of the 35 Black Swans built to orders placed after 1st April 1939 IOTL. This was because the Loch design could be built faster and it released capacity in the warship yards that could be used to build warships that could not be built in the merchant shipyards. It was also because the Royal Navy already had 32 escort sloops built or building that were armed with six or eight 4" guns in twin HA mountings and a HACS instead of the 5 that it had IOTL and the RIN had 4 sloops built or building carrying that armament instead of none.

IOTL the Australian sloop programme ended when Cockatoo Dockyard completed the Grimsby class escort sloop HMAS Warrego in August 1940. The yard received orders for 6 Tribal class destroyers before war was declared and had laid down 2 of the 3 ships that would actually be built before Warrego was completed. Furthermore, 24 of the 60 Bathurst class corvettes (they were officially minesweepers, but that was a cover) that would be built in Australia, which included the orders for 5 of the 8 Bathursts that Cockatoo would build.

ITTL the Australian sloop programme also ended when HMAS Warrego was completed. However, ITTL she, in common with her sisters, was completed with an armament of six 4" guns in three twin HA mountings and a HACS anti-aircraft fire control system. The only other change was that Cockatoo and the other Australian shipyards were building River class frigates instead of the OTL mix of Tribal class destroyers and Bathurst class corvettes.

The British Frigate Programme

IOTL the escort sloops of the Bridgewater to Black Swan classes were excellent designs. Unfortunately, there wasn't the shipyard capacity and more importantly the engine making capacity to build them in the numbers that would be required in wartime. This led to the construction of 135 Flower class and 10 Improved Flower class corvettes, which were followed by 57 River class frigates, 28 Loch class frigates, 27 Bay class frigates and 44 Castle class corvettes. That is a total of 301 corvettes and frigates including 8 ships of the Bay class that were completed as dispatch vessels, rescue ships, depot ships and survey ships.

The River class frigate was a modification of Black Swan escort sloop that could be built in shipyards with no previous experience of building warships. Depending upon the source the Castle class corvette was either an enlarged Flower class corvette or a diminutive of the Loch class frigate that could be built on slipways that were too short for a Loch or a Bay.

According to Leo Marriott in Royal Navy Frigates 1945-1983.

The "Loch" class of AS frigates represented the final product of wartime experience in frigate design and operation. It was basically a redesigned version of the successful "River" class and was optimised for mass production on dispersed sites. To facilitate this, the ship was built up of prefabricated sections which could be constructed at the dispersed sites and moved by road or rail to an assembly slipway. Each section had maximum dimensions of: length 29ft; width 8ft 6in; and height 8ft 6in. Maximum weight of each section was set at 2½ tons to suit crane capacity at the shipyards. Eighty per cent of the hull and superstructure was made up of prefabricated units, the rest of the structure being worked in by the assembly yard. The setting up of the organisation necessary to run a widely dispersed production system was a massive task, and took some time. However, once in operation, the time required to complete a frigate was drastically reduced. Whereas the average time to complete a conventionally constructed "River" class frigate was in the order of 15 to 18 months, a prefabricated "Loch" class frigate was completed in an average time of 10 or 11 months. Had the war continued past 1945, building times would probably have fallen even more as the tempo of production increased.

The Bay class was the anti-aircraft version of the Loch class. That is it had the same hull and machinery, but it was armed four 4" guns in HA mountings and an anti-aircraft fire control system.

ITTL there wasn't enough shipbuilding capacity to build escort sloops in the number required either and that was despite the extra destroyers and sloops that had been built between 1927 and 1939. Furthermore, the Admiralty preferred to reserve the capacity that was available to build "proper" small warships for destroyers and build as many minor war vessels as possible in merchant shipyards. It also wanted something better than the OTL Kingfisher and Flower classes because it didn't underestimate the range of Germany's submarines and it wanted ship that could be given a heavy anti-aircraft armament for the east coast of England and other areas where trade had to be protected form air attack as well as submarine attack. Finally, it wanted the "mobilisation sloop" which became the Loch class frigate to be prefabricated to reduce building time and to minimise the disruption that German bombing of the shipyards was expected to create.

IOTL the first 120 Flowers were ordered as follows:

30 on 25th July 1939 (AFAIK including the 4 ordered by the French Navy) under a supplementary estimate to the 1939-40 Estimates​

30 on 31st August 1939 under a supplementary estimate to the 1939-40 Estimates​

20 on 19th September 1939 under the War Emergency Programme​

10 on 21st September 1939 under the War Emergency Programme​

10 on 12th December 1939 under the War Emergency Programme​

10 on 15th December 1939 under the War Emergency Programme​

10 from Canadian yards on 20th January 1940 (7) and 22nd January 1940 (3)​

ITTL the first batch of 30 Lochs was ordered on 25th July 1939 and the second batch of 30 Lochs was ordered on 31st August 1939 were direct replacements for the first 2 batches of Flowers. However, the 60 Lochs ordered under the War Emergency Programme were ordered on 19th September 1939 to facilitate the mass production scheme and they were all ordered from British yards for the same reason.

A minimum of 346 Loch class were built ITTL. 284 were completed as anti-submarine frigates instead of the 135 Flowers, 10 Flowers built to British account in Canada, 10 Improved Flowers, 44 Castles, 57 Rivers and 28 Lochs built IOTL. 62 were completed as anti-aircraft frigates instead of 35 (out of 37) Black Swans, 19 Bays that were completed as AA frigates and the 8 Bay class that were completed as dispatch vessels, survey ships and depot ships.

IOTL the Royal Navy received 136 minor war vessels built in the USA under Lend Lease. That is, 78 Captain class destroyer escorts, that were designated frigates by the Royal Navy, 21 Colony class frigates, which were American versions of the River class frigate, 15 Kil class corvettes and 22 Catherine class minesweeping sloops. They were delivered between February 1943 and August 1944. ITTL the British shipbuilding industry was able to complete 21 additional Loch class between October 1943 and June 1944 instead of the 21 Colony class. It might be able to build complete 115 additional Lochs between February 1943 and August 1944 in place of the Captain, Catherine and Kil classes. The 136 ships built in the USA were commissioned into the USN or other Allied navies or they weren't built at all and the Americans used the resources to build more LSDs and LSTs, which is the option that I prefer.

The 35 Bays built instead of the 35 Black Swan class ordered after 1st April 1939 had turbine machinery and a larger percentage of the 301 Lochs and Bays built instead of the other 301 frigates and corvettes built IOTL had turbine engines too. This was because more destroyers were built in peacetime and because the TTL scrap and build scheme encouraged the ship owners to buy ships with turbine engines.

The Australian Frigate Programme

The OTL River class frigate was designed alongside the Loch class ITTL so it could be built when the number of ships being build did not justify building Loch class frigates.

ITTL the Commonwealth of Australia ordered 2 River class frigates for the RAN fro Cockatoo Dockyard in January 1939 instead of the first 2 Tribal class destroyers of OTL and another 4 from Cockatoo in May 1939 instead of the second batch of 4 Tribals. The first pair was laid down instead of the first 2 Tribals and completed by the end of 1941 and the second quarter was laid down in the middle of 1940 and completed by the middle of 1940.

60 additional River class frigates were built in Australian yards ITTL instead of the 60 Bathurst class corvettes and 12 River class frigates built ITTL.

This made a grand total of 78 River class built in Australia ITTL instead of the 75 warships built IOTL (3 Tribal class destroyers, 12 River class frigates and 60 Bathurst class minesweepers/corvettes.

The Canadian Frigate Programme

IOTL 107 Flower class corvettes and 70 River class frigates were built in Canadian yards IOTL and that includes the 10 Flowers that were built to British account in the War Emergency Programme.

I want Canada to build 177 River class frigates ITTL, but it might not be possible. IOTL the last 27 Flowers had to be built to that design because they were built in shipyards on the Great Lakes and the locks were too small to take the River class frigate and these yards built 32 of the first 80 Flowers.

AIUI the St Lawrence Seaway was proposed in the early 1930s but it wasn't built until after World War II and opened in 1959. However, bringing it forward 20 years seems to be a rather drastic way to get 59 Rivers built. It might be possible for Canada to build 177 frigates if the other yards build the mass production version of the River, i.e. the Loch. If that isn't possible the Great Lakes yards will have to build 59 Halcyon class minesweepers instead of the Flower class corvettes that they built IOTL.

The Minesweeping Sloop Programme

93 were built in British yards IOTL consisting of 45 Bangor class and 48 Algerine class that were larger. The first 42 Bangors were ordered in the 1939-40 Estimates and War Emergency Programme. The 3 remaining Bangors and all 48 Algerine class were ordered in subsequent building programmes. 4 had diesel engines, 45 had reciprocating engines and 44 had turbine machinery.

ITTL the Admiralty decided to keep building the Halcyon class because it was a satisfactory design and the UK had more shipbuilding capacity. If necessary it would be redesigned to allow production in yards with no experience of building warships analogous to the redesigning of the Black Swan class into the River class.

IOTL the Bangor class was succeeded by the Algerine class because the Bangoer design was too small for the all the equipment that was required. There was no need to discontinue construction of the Halcyon class in favour of a larger design because it was bigger than an Algerine. That is its overall length was 245ft that is 20 feet longer than an Algerine. However, its beam of 33½ feet was 2 feet narrower than an Algerine's 35½ feet.

Therefore, 93 Halcyons were built to orders placed after 1st April 1939, which with the 39 ordered to 31st March 1939 ITTL brought the total built in British yards to 132. A greater proportion of the 93 minesweepers built to orders placed after 1st April 1939 had turbine machinery and none of them had diesel engines.

At least 123 Halcyons were built in Canada in place of the 60 Bangors and 63 Algerines that were built IOTL. I wrote at least because some of the yards may not be able to build River class frigates instead of the Flower class corvettes that they built IOTL and if that is the case they will build Halcyon class minesweepers instead.

4 Halcyons were built in India instead of the 4 Bangors built IOTL. 3 more were ordered from Indian yards in place of the 3 Bathurst class ordered IOTL, but in common with those ships they weren't completed before the war ended.

4 Halcyons were built in Hong Kong instead of the 4 Bangors built IOTL and in common with OTL they were captured by the Japanese before they were completed.

 

[sonofpegasus]

I Hope ITTL the Hunt class escort destroyers are built from the start with the wider hull and so avoid the stability problems that so blighted the OTL vessels.
Fantastic wotrk by the way!

 

[ArtosStark]

I second that. Always enjoy reading your naval improvements. And you covered Canada and Australia in this one! Awesome!

 

[NOMISYRRUC]

I Hope ITTL the Hunt class escort destroyers are built from the start with the wider hull and so avoid the stability problems that so blighted the OTL vessels.

I second that.

No. The Director of Naval Construction's department was still overloaded with work and they still made the mistake in the design calculations.

Fantastic wotrk by the way!

Always enjoy reading your naval improvements. And you covered Canada and Australia in this one! Awesome!

That's much appreciated. Especially after the amount of time that it took to work it out and write it.

 

[dave_r_gilbert]

Brilliant work.
Your highly detailed work and comparison set my own thoughts going and I came up with much the same ideas, with a couple of variations.

1. The old V&W destroyers.
The 1st London treaty put a limit on destroyer tonnage, but defined destroyers effectively as vessels of
a) 600 to 2000 tons,
b) more than 4 guns of 3" to 6",
c) capable of carrying torpedoes
d) more than 20 knots. In the 2nd London treaty this was changed to 25 knots.
My thought here was to get the 25 knot limit in the 1stLNT, and create available destroyer newbuild tonnage by converting the V&Ws so they no longer qualified.
Replacing torpedoes with ASW, and 1 boiler room removed to reduce speed(replaced with bunkerage in the lower space made available, and accommodation above), Also (possibly) replace 4"/4.7" with 2x2 4" and HACS.
Put them into reserve, and use them as recruitment/PR vessels in the early 30's by giving aspiring officers/recruits training trips to/from Gib escorting "convoys" as part of the perisher course.
I think there was a noblewoman navy campaigner at about that time who was a political pain. Pay her off as figurehead for the recruitment campaign?
Once the 2LNT comes into play they no longer need to be converted to free up tonnage, but the programme continues to boost the number of longer range escorts, as the new build destroyers are providing all the required fleet destroyers.

2. Instead of replacing the Black Swans with Hunts, I went the other way and replaced the Hunts with Black Swans.
Much the same AA suite, 25 kts(hunts) vs 20, 3600(hunts) vs 7000 range.
I think the swans were preferred for ASW work, the longer range being more valuable than the speed.
And not designing the Hunts reduces the stress on the DNC department because the swans had already been designed and were in production.

3. Instead of transferring all Kingfishers to Halcyons in 36 and 37, transfer most, but build 1 or 2 Flower class.
The rationale here is that the RN knew they would need a shedload of escorts in the event of a war, so it would make sense to build 1 or 2 and try them out, to uncover any problems.
Running them with dummy convoys for the perisher course (see V&W class above) leads to the River/Loch/Bay frigate design, and the Castle Corvette design.

3. Is it feasible (or desirable) to replace all corvette construction with frigates?
In OTL the Castle class was built because some slips weren't long enough for the Frigates.
Would it be possible to replace all corvette production in TTL unless all short slips were replaced?
In addition the production time on corvettes was slightly less, and they had smaller crews. Manpower shortage was a problem later in the war.
I think replacing some, or even most, corvette production with frigates would be more achievable than all of them.
And may even have been better in terms of resource and manpower usage.

I'm not trying to throw any shade on your work here, just a few alternates.

 

[NOMISYRRUC]

There's a big mistake in Post 608.

My Canadian built Flower class spreadsheet didn't include the 15 ships built to American account under Lend Lease that were taken into service by the Royal Navy and US Navy.

That increases the number of Flowers built in Canada IOTL from 107 to 122. The Americans also ordered 10 River class frigates from Canadian yards under Lend Lease and they are included in the 70 ships mentioned in Post 608.

ITTL the Americans would want to order another 15 frigates, but may be forced to order 15 Halycon class minesweepers instead of the Flowers bought IOTL. A lack of suitably long slipways could be why they ordered 15 corvettes and 10 frigates from Canadian yards IOTL.

It's likely that there are other mistakes, but I'm not going to correct them.

 

[NOMISYRRUC]

I think there was a noblewoman navy campaigner at about that time who was a political pain. Pay her off as figurehead for the recruitment campaign?

Do you mean Lady Houston who paid Supermarine £100,000 so they could enter the 1931 Schneider Trophy competition?

 

[NOMISYRRUC]

From my workings spreadsheet.

 

[dave_r_gilbert]

Do you mean Lady Houston who paid Supermarine £100,000 so they could enter the 1931 Schneider Trophy competition?

Yes, I think that's her.
I find it hard to believe there could be 2 such women around at the same time.
If her Wikipedia article is even 50% accurate she must have been a remarkable woman, and an imperial pain in the a**e for the government,
Anything that even partially diverted her energies away from slagging them off would have got any amount of extra money from the treasury.

 

[PMN1]

2. Instead of replacing the Black Swans with Hunts, I went the other way and replaced the Hunts with Black Swans.
Much the same AA suite, 25 kts(hunts) vs 20, 3600(hunts) vs 7000 range.
I think the swans were preferred for ASW work, the longer range being more valuable than the speed.
And not designing the Hunts reduces the stress on the DNC department because the swans had already been designed and were in production.

Something I just noticed on the wiki link

Hunt-class destroyer - Wikipedia

en.wikipedia.org

The Hunts were modelled on the 1938 escort sloop Bittern, a 262-foot (80 m) ship of 1,190 tons with 3,300 shp (2,500 kW) on geared turbines for 18¾ knots and an armament of three twin Mark XIX mounts for the QF 4-inch (102 mm) gun Mark XVI.

 

[NOMISYRRUC]

The Royal Navies of the British Empire and Commonwealth at 3rd September 1939
The Differences Between OTL and TTL​

Introduction

This is a summary of what I've posted so far.

Submarines

There were 59 (12 old and 47 new) in service at the outbreak of war in both timelines, but the number of submarines under construction or on order was increased from 12 to 26 because 32 boats were ordered in the 4 financial years 1936-37 to 1939-40 instead of 18.

Aircraft Carriers
The Situation in September 1939 IOTL

Ark Royal, Courageous, Eagle, Glorious, Furious and Hermes (six ships) were in commission. Furious was the deck landing training ship and the others were operational warships. Five aircraft carriers were under construction and a sixth was on order. I haven't counted Argus because she was serving as a depot ship for De Havilland Queen Bee target drones.

The five operational aircraft carriers had an aggregate capacity of 15 squadrons if Ark Royal was rated as a 48-aircraft ship and the Naval Aviation (which was as the Fleet Air Arm's official name form May 1939) had 15 aircraft carrier squadrons with 9-12 aircraft each for a total of 162 aircraft. However, six squadrons were embarked on Ark Royal instead of four and Courageous had two squadrons embarked instead of four.

There were also 70 seaplanes and amphibians operating form 2 seaplane carriers (Albatross and Pegasus), capital ships and cruisers.

The Situation in September 1939 ITTL

There were ten aircraft carriers consisting of one brand new 27,000-ton ship, four ships of the 22,500-ton type, Courageous, Eagle, Furious, Glorious and Hermes. Furious was the deck landing training ship and the remainder were operational warships. Five aircraft carriers were under construction. Two more were on order, but they wouldn't be laid down until 1942-43.

The 27,000 ton aircraft carrier was named Illustrious. The 22,500 ton ships were named Benbow, Emperor of India, Marlborough and Ark Royal. The 22,500 ton ships were built in that order and were known as the Benbow class.

In common with OTL Argus hasn't been counted because she had been converted into a depot ship. Her entry in the OTL edition of Jane's Fighting Ships 1939 had her in the depot ships section rather than the aircraft carriers section and that was also the case in the TTL edition.

The nine operational aircraft carriers had an aggregate capacity of 31 squadrons because the Benbow and Illustrious classes were rated as 48-aircraft ships. The TTL Naval Aviation had 366 aircraft in 31 squadrons with 9-12 aircraft each.

There would be more than 70 catapult aircraft because there were more capital ships and cruisers equipped to operate them ITTL.

Capital Ships

There were 15 ships consisting of Hood, 2 Nelson class, 5 Queen Elisabeth class, 5 Royal Sovereign class and 2 Repulse class.

IOTL Queen Elizabeth, Renown, Valiant and Warspite received full modernisations, while Malaya and Repulse had partial modernisations. The Royal Sovereign class and Hood had their anti-aircraft armaments upgraded with the fitting of twin 4" AA guns, 2pdr pom poms and HACS AA directors.

ITTL the Admiralty persuaded the Government to allow full modernisations all 5 Queen Elizabeth class, Renown, Repulse and Hood and for the Royal Sovereign class to have their machinery replaced by 1940 in return for having the battleship building holiday extended to the end of 1936. The full modernisations were done 2 or 3 ships at a time between 1930 and 1939.

Nelson and Rodney were 12 years in old in 1939 and were next in the queue for a major refit, but they could not be carried out because ware broke out. IIRC I had written that they had started their refits when war broke out and work had proceeded too far for them to be stopped. However, I've now changed my mind.

I can't remember what I wrote about new capital ships. 5 would still be laid down in 1937 and 2 would still be laid down in 1939. I usually say that the Admiralty stays with an armament of nine 15" guns for the King George V class to avoid the delay that was created by having to design first the quadruple 14" turret and then the twin 14" turret.

Cruisers

IOTL the Royal Navies of the British Empire and Commonwealth (BEC) had 65 cruisers of 469,240 tons as follows:

Under construction or on order were 27 ships of 183,375 tons (11 Colony class and 16 Dido class) that were due to be completed 1940-42. However, the last ship wouldn't be completed until January 1944.

The ITTL cruiser force consisted of 96 ships of 683,075 tons as follows:

Under construction were 20 ships of 129,600 tons (16 Dido class and 4 Edinburgh class) that were due to be completed 1940-42. They were actually completed between November 1939 and May 1943.

Fleet Destroyers

IOTL there were 192 destroyers (79 old and 113 new plus 24 under construction) including 5 old destroyers in the RAN and 7 new destroyers in the RCN. The old destroyers were 9 leaders of the Scott & Shakespeare classes, 58 V&W class and 12 R&S class. The flotilla leader Wallace and 12 V&W class had been converted to escort destroyers. The new destroyers were 79 A to I class, 16 Tribal class and 16 Javelin class. The destroyers under construction were 8 Javelin class and 16 Lighting class.

ITTL there were 236 destroyers (63 old and 173 new plus 32 under construction) including 9 new destroyers in the RAN and 13 new destroyers in the RCN. The old destroyers were 9 leaders of the Scott & Shakespeare class and 56 V&W class. None of them had been converted to escort destroyers. The new destroyers were 141 A to I class (which included the 9 RAN and 13 RCN ships) and 32 Javelin class. The 32 destroyers under construction were Javelin class.

Minor War Vessels

There were 95 in commission in both timelines including 4 in the RAN and 7 in the RIN. There were 111 under construction or on order IOTL (including 2 RAN and 2 RAN) and 120 under construction or on order ITTL (still including 2 RAN and 2 RIN).

There were escort sloops (9 old and 32 new) including 4 in the RAN and 6 in the RIN in both timelines. However, all 32 of the new ships (including 2 RAN and 2 RIN) had a powerful gun armament of six or eight 4" guns in twin AA mountings and a HACS director. Only the 5 newest RN ships had that armament IOTL.

8 escort sloops (4 RN, 2 RAN and 2 RIN) were on under construction or order in both timelines. However, the 2 RAN ships would be completed with six twin 4" guns in twin HA mountings and have a HACS while the RIN ships and 2 of the RAN ships were ordered 2 years earlier than OTL.

There were 2 old patrol sloops (including one RIN) and 26 old minesweeping sloops in both timelines. However, there were 27 new Halcyon class minesweepers ITTL instead of the 21 Halcyons and 6 new patrol vessels of the Kingfisher class of OTL. 3 additional Kingfisher class and 20 Bangor class minesweepers were on order IOTL, but ITTL 32 additional Halcyon class were under construction were on order.

20 Hunt class escort destroyers were under construction or on order in both timelines. However, 60 Loch class frigates were on order instead of 60 Flower class corvettes.

 

[NOMISYRRUC]

2. Instead of replacing the Black Swans with Hunts, I went the other way and replaced the Hunts with Black Swans.
Much the same AA suite, 25 kts(hunts) vs 20, 3600(hunts) vs 7000 range.
I think the swans were preferred for ASW work, the longer range being more valuable than the speed.
And not designing the Hunts reduces the stress on the DNC department because the swans had already been designed and were in production.

I haven't replaced the Black Swans with Hunts.

The 2 built under the OTL 1937-38 Estimates were still built ITTL. The 4 ordered for the UK and India in the 1939-40 financial year IOTL were ordered in the 1938-39 financial year ITTL and thus were completed in 1940 instead of 1941.

I've replaced the 31 Black Swans built during the war with 35 Bay class AA frigates. This was because Bays were quicker to build and because the Bays were built in merchant yards and the Black Swans were built in warship yards which increased the capacity of the warship yards to build other types of "proper" warship.

Having written that I did consider building 86 Black Swans instead of the 86 Hunts because my understanding of OTL is that the Admiralty ordered the 86th Hunt in 1940 but continued to build Black Swans in small numbers because it thought the latter was the better ship. Then I discarded that idea in favour of building 86 additional Bay class AA frigates because they could be built faster than Black Swans and and it released capacity in the warship yards that could be used to build more "proper" warships. Plus it would have increased the number of frigates ordered in the 1939-40 financial year from 120 to 180 which strengthened the argument for building the Loch class instead of the River class because the former was designed to be mass produced.

 

[NOMISYRRUC]

1. The old V&W destroyers.

The 1st London treaty put a limit on destroyer tonnage, but defined destroyers effectively as vessels of
a) 600 to 2000 tons,
b) more than 4 guns of 3" to 6",
c) capable of carrying torpedoes
d) more than 20 knots. In the 2nd London treaty this was changed to 25 knots.

My thought here was to get the 25 knot limit in the 1stLNT, and create available destroyer newbuild tonnage by converting the V&Ws so they no longer qualified.

Replacing torpedoes with ASW, and 1 boiler room removed to reduce speed(replaced with bunkerage in the lower space made available, and accommodation above), Also (possibly) replace 4"/4.7" with 2x2 4" and HACS.

Put them into reserve, and use them as recruitment/PR vessels in the early 30's by giving aspiring officers/recruits training trips to/from Gib escorting "convoys" as part of the perisher course.

I think there was a noblewoman navy campaigner at about that time who was a political pain. Pay her off as figurehead for the recruitment campaign?

Once the 2LNT comes into play they no longer need to be converted to free up tonnage, but the programme continues to boost the number of longer range escorts, as the new build destroyers are providing all the required fleet destroyers.

There were 64 V&W class destroyers at the POD (i.e. 1929) and IOTL there were 60 left at the end of 1936 and 58 left on 3rd September 1939.

That is, 4 were scrapped while the 1LNT was in force (one 1931 and 3 in 1936), one was scrapped in 1938 and one was scrapped in 1939 leaving 58 in service with the RN and RAN on 3rd September 1939. As far as I can tell the 6 ships that were scrapped were discarded because of their poor material condition rather than the need to keep within treaty limits or financial constraints.

The OTL 1LNT did limit the British Commonwealth to 150,000 tons of destroyers, but it allowed that total to be reached gradually between 1930 and the end of 1936. Furthermore, the Treaty became a dead letter when the 2LNT was signed in March 1936 so I believe that the 3 V&W class destroyers that were scrapped in 1936 must have been scrapped because they weren't worth keeping because of their material condition rather than to keep withing treaty limits. There weren't any Treaty limits on the number of destroyers after 1936 and the Treasury had released the purse strings considerably, which is why I believe that the 2 ships scrapped between 1937 and 1938 were discarded because they were in poor condition. The 5 destroyers scrapped 1931-37 were completed in 1917 and the ship scrapped in 1938 was completed in 1918.

Most of what you propose is unnecessary in my TL. Firstly, in my TL's version of the 1LNT allows the British Commonwealth to have 200,000 tons of destroyers on 31st December 1936 and in 1930 the plan was to have

23 overage destroyers of 26,990 tons (2½ flotillas) at the end of at the end of 1936 to make a grand total of 146 destroyers of 196,649 tons. The old destroyers would consist of 3 Scott class leaders and 20 V&W class which would be combined with the 4 new RCN destroyers to form 3 flotillas.

8 of the 64 V&W class destroyers left at the POD were scrapped in 1935 in my TL because they were replaced by the extra flotilla of F class destroyers that was completed in 1935. However, the 4 Scott & Shakespeare class and 36 V&W class that were scheduled to be scrapped in 1936 to keep the British Commonwealth within the 200,000 ton quota were reprieved. That is first because of the Abyssinian Crisis and then pending the result of the Second London Naval Conference because the resulting treaty was expected to abolish the tonnage quotas, which it did.

This left the British Commonwealth with 9 Scott & Shakespeare class leaders and 56 V&W class destroyers at the end of 1936.

As I already wrote there were 64 V&W class destroyers in 1929. The Admiralty discarded 4 in 1931-36 and another 2 over 1937-38 which left 58 in 1939. There were also 12 leaders of the Scott & Shakespeare classes in 1936 IOTL. 2 Shakespeare class were scrapped in 1936 and as the 1LNT was a dead letter this was probably because they were in poor condition. The Admiralty had the Scott class leader Bruce sunk as a target on 22nd November 1939, which was 10 weeks after the declaration of war, and indicates how useful that ship was. This left them with 9 leaders of the Scott & Shakespeare class.

ITTL the Admiralty didn't scrap any old destroyers between the beginning of 1936 and September 1939 so there were 9 Scott & Shakespeare class leaders and 56 V&W class destroyers at the outbreak of World War II. That's the same number of leaders as OTL and only 2 destroyers fewer than OTL. All the R&S class destroyers were scrapped before the end of 1935 ITTL which meant there were only 63 old destroyers at the outbreak of World War II instead of 79. However, there were 173 new destroyers ITTL instead of 113 so there was a net increase of 44 destroyers of all ages, that is from 192 IOTL to 236 ITTL and all the extra ships were being used for trade defence.