Some excellent ideas and points thus far; I particularly like the contributions of Nomisyrruc and Riain as ever, but everyone has come out with some good stuff.
Assuming that WW2 cannot be avoided, the aim is to build up the best possible fleet to be able to fight and win said war (at sea) as soon as possible and as efficiently as possible, Given that future knowledge is allowed, I'd divide the issue into a number of subsidiary ones:
A.) Fleet Size
The peacetime RN cannot necessarily be built up into an 'instant wartime fleet' by 1939, but a lot of the groundwork can be done. I'll use this baseline data as my starting point for discussion:
The RN Naval Standards of 1934–36 (Hyperwar, British War Production Chapter II)
Naval strength required by 1942:
A.) Naval strength 1934
B.) 'D.R.C. standard' 1934–35 (Defence Requirements Sub Committee)
C.) 'Two-power standard' 1935–36
Flotillas of destroyers
Escort vessels, minesweepers, etc.
The increase in battleships can be accomodated with some planning, whilst the major issues come in aircraft carriers, cruisers, destroyers and escorts, but these are not insurmountable when spread over ~15 years. I particularly agree with Riain's point on prioritising the big ships in peacetime and putting in place the small ship designs for wartime mass production.
My aim will be to have more destroyers than required under the Two Power Standard, with the V/Ws to be eventually reclassified as escorts.
B.) Fleet Composition
No big changes from the norm here. There will be a principle of using every year to the maximum and getting the most out of the rearmament period when it comes.
I have this from my old files; Nomisyrruc may have a more accurate version, but I think this is around the mark, albeit might be off in some of the 1930s budgets
1923, 58m, 1 submarine
1924, 56m, 5 8in cruisers, 2 destroyers
1925, 61m, 4 8in cruisers
1926, 58m, 3 8in cruisers , 6 submarines
1927, 58m, 1 8in cruiser, 9 destroyers, 6 submarines, 2 sloops
1928, 57m, 9 destroyers, 4 submarines, 4 sloops
1929, 56m, 1 6in cruiser, 5 destroyers, 3 submarines, 4 sloops
1930, 51.7m, 3 6in cruisers, 9 destroyers, 3 submarines, 4 sloops
1931, 51.6m, 3 6in cruisers, 9 destroyers, 3 submarines, 2 sloops, 2 minesweepers
1932, 50.5m, 3 6in cruisers, 9 destroyers, 3 submarines, 2 sloops, 2 minesweepers
1933, 53.6m 3 6in cruisers, 9 destroyers, 3 submarines, 2 sloops, 1 patrol vessel, 2 minesweepers
1934, 56.6m, 1 aircraft carrier, 4 6in cruisers, 9 destroyers, 3 submarines, 2 sloops, 2 patrol vessels, 2 minesweepers.
1935, 60m, 3 6in cruisers, 16 destroyers, 3 submarines, 1 sloops, 2 patrol vessel, 3 minesweepers
1936, 70m, 2 battleships, 2 aircraft carriers, 2 6in cruisers, 5 5.25in cruisers, 18 destroyers, 8 submarines, 2 sloops, 1 patrol vessel, 3 minesweepers
1937, 78.1m, 3 battleships, 2 aircraft carriers, 5 6in cruisers, 2 5.25in cruisers, 15 destroyers, 7 submarines, 3 sloops, 3 patrol vessels, 4 minesweepers.
1938, 93.7m, 2 battleships, 1 carrier, 4 6in cruisers, 3 5.25in cruisers, 3 fast minelayers, 3 submarines, 1 aircraft maintenance ship
1939 69.4m, 2 battleships, 1 carrier, 2 6in cruisers, 1 fast minelayer, 16 destroyers, 20 hunts, 2 sloops, 56 corvettes, 20 minesweepers
As of 1923, the useful ships for The Next War are the 5 QEs and the forthcoming Nelson and Rodney. The 5 Rs, being unfortunately deficient compared to their preceding class, will get a shorter frontline life, but as they have been built and paid for and are still relatively new, try to get them modernised to get the most possible out of them. Keeping a rebuilt Tiger as a second class battlecruiser with a view towards heavy escort would allow 4 battlecruisers. That gives 10 ships that can be taken into a war from 1939 plus 5 Rs and Tiger in second line duties but not hopelessly behind as in @. After after rolling rebuilds through the 1930s, this leaves us short of the mark by 10. Anything older than the QEs is going to be gone by the mid 1930s in any event.
The first part of the solution to that comes in a KGV equivalent ready to go down the day that they are allowed under the terms of the WNT and LNT combo; if the latter can be wangled a bit to cut off in 1935 as compared to 1936, all the better. 6 ships of 42,000-45,000t with 9 x 16", 24 x 5", 15" belts and as fast a speed as possible will be the aim there, with long lead in items ordered beforehand to allow for maximised production rates.
Follow up with 6-8 larger Lion class ships, depending on foreign challenges and changes.
As said above, built a 24,000t Ark Royal and a sister between 1928 and 1934, then focus design efforts on a 32,000t follow on class with the same large air wing. The aim will be for 12 of these built or building by 1939, plus the earlier pair and a rebuilt Courageous and Glorious for 16* fleet carriers, of which at least 10 will be in service by kick off.
A trade protection design can be commenced in the early 1930s, leaning towards a Majestic class in general dimensions and capacity, whilst a smaller Woolworths/escort carrier design should be prepared over time and gradually start construction in the immediate years before the war.
Get the FAA back and aim for three decent types of monoplane aircraft - a fighter, recce/dive bomber and torpedo bomber
Getting to the 100 mark isn't impossible, but requires a bit of thought. The 1920s will be taken up with County type cruisers, but in the last few years of the decade, start production of an 8000t 8 x 6" Leander analogue. Keep these going at a steady rate to replace the old Towns and earlier Cs as they go.
Town class should be similar to @ size and armament; don't go down for the repeat Towns/Crown Colonies and have the Didos as a 7500-8000t 12 x 5" AA ship
If we know we need them and know the general type, then expedite building the buggers and build them of a decent size, up to the L/M size of the late 1930s as a model. Start with a full flotilla in 1924 then go at 9/year in 25, 26, 27, 28, 29, 30, 31, 32 and 33, then 18 a year after that until 1937 or 1938, then accelerate again. The rearmament era budget will be a lot more flexible and allowing for such shifts if the 'norm' is higher.
Build sloops regularly through the 1920s, utilising the WNT exception (see below) and start designs for an escort destroyer, frigate and corvette. Roll the latter trio into gradual production from the mid 1930s at 4, 6 and 8/year, then rising
- 67 V/W class destroyers to be reclassified as escort destroyers through the 1930s as replaced in the fleet role by new construction. Together with the 120 interwar sloops outlined below and the initial Hunts (16+), frigates (24) and corvettes (32) and the escort numbers are covered.
- Keeping armour production and gun pit capacity through the treaty holiday and maintaining necessary slip capacity to accelerate when needed for full rearmament is the challenge of the 1920s
- In terms of the eternal debate beloved of AH and other places on DP secondaries, a choice needs to be made. Future proofing this choice may also be a good notion, given that many of these ships will not be built just for a war and then thrown away, but live on (hopefully). 4.5" and particularly 4.7" gets a lot of love around here, but is a bit small for the longer run and for ASuW. With enough time and the idea of future knowledge, why not just design/copy a 5" gun that can arm frigates and destroyers and provide secondaries for everything bigger, whilst also having commonality with land based HAA mounts? I have a curious liking for 125mm as a ballistic sweet spot, but 127mm does just as fine
I believe that the following is by Mark Bailey:
"With perfect hindsight it is hard to ignore the need for more 300ft, twin screw 20knot escorts early in the war, though having said that it seems pretty clear to me the RN and Dominion navies should have ordered more Sloops – 1930-1936. They are essentially unlimited by the London treaty. Their cost is very low - in the 100-200,000 pounds band. Their main limitation is the dual role minesweeping. This limited their draft – which in turn influenced seakeeping. It also set their power as that required to tow the sweep at 12 knots – which worked out to a top speed of 16.5-17 knots. They dropped the minesweeping role for the Bitterns – added 50% more power for 19knots and produced some pretty useful units – DP AA – asdic – depth charges 1200 tons – but not in enough numbers, and built to warship standards with turbines, not suited to mass production.
Building a full 8 sloop flotilla every year 1930-1936 adds roughly 1 million pounds to each years estimates in terms of construction and repair – as well as spread work through the depressed shipbuilding industry. The end result is over 30 additional ocean going escorts. And there is no need to maintain these additional ship in commission – they can sit in reserve, rotating with the historic ships in commission, foregoing much increase in operating cost.
This leads back to – IMHO – one of the main issues that dogged the RN 1939-1942. Its not the Treaties, its not so much the ten year rule, though the ravages of that were bad – it was rescinded in 1935 and its worse excesses made good 1935-1936 through some supplementary estimates. The worst problem the RN faced between the wars was the drop in its annual estimate from the early mid 20’s plateau of 57-61 million pounds per annum from 1923-1928 (pretty much the Beatty years) through a trough of 1928-1935 with a nadir in 1932 of 50.5 million pounds.
Maintaining the estimates at 57 million pounds through 1928-1935 results in a cumulative additional expenditure of 22 million pounds.
The RN could not do too much more with cruisers and destroyers 1930-1936 because of treaties, but what they could do with this money would include.
* Building a full flotilla of sloops each year – 6 million pounds.
*Avoid economies in cruiser and destroyer programs - 1 million pounds.
*Bring forward the carrier program – laying down Ark Royal in 1931 rather than 1935 – 4 million pounds, to be followed by a second new carrier with the benefit of Ark Royal experience as per historic in the 1934 estimate.
*Building up FAA numbers and aircrew reserves - $? Here – Chatfield roughly costed operational embarked aircraft including replacement, maintenance and operating costs at 15,000 pounds per annum. – prices forming an additional squadron in 31, 33, 34, 35 at 2 million pounds. Aircraft are dear.
* This leaves 9 million pounds that could be spent on modernisation of the battlefleet 1930-1936 – an area where the RN significantly underspent the USN and IJN in this era. The RN spent 1940-41 trying to face off the modern Italian fleet in the Mediterranean using hetrogenious squadrons of battlecruisers, modernised QE’s and unmodernised and desperately slow R class ships, leading to multiple situations were a single ship was exposed and isolate against multiple enemy capital ships with the distant support of an 18knot R with short ranged guns. It’s a bit early for modernisations that incorporate DP armerment – but re-machining to re establish original speeds, modernised horizontal protection, modern directors and fire control and increased main armament elevation are possible – and on roughly 2-2.5 million pounds. At this rate we could fit in another 3-4 reconstructions in the 1930-1936 period – giving the RN are far more capable and homogenous battlefleet by 1940."
Depending on the extent of the foreknowledge, the battlefleet modernisation can be spread out; the cruiser and destroyer plans dealt with and build a full flotilla of sloops every year from 1924 to 1938 for 120 ships ready to go in 1939.