A better Imperial Japanese Navy
- Thread starter Ozpin
- Start date
The averages are a great way to put the respective shipbuilding efficiencies, much appreciate your efforts and knowledge as always. Do you have such a comparison by any chance for the prewar cruisers, especially the treaty cruisers?
There is still an element to add though, namely the need of the japanese to practically rebuild many of their LNT destroyers as well as significantly modify the rest built to date due to the Tomozuru and 1935 incidents. That hogged up dock space and consumed many resources. Same will be with the post LNT cruisers. But ITTL since we postulate "cheating more", that time and resource waste largelly shouldn't happen.
Submarine building times
- The 44 US submarines ordered from FY1929 onwards and completed by Pearl Harbour were built in an average of 20 months. That is 14 months from laying down to launch and 6 months from launch to completion.
- The 27 Japanese submarines ordered from the 1931 Programme onwards and completed by Pearl Harbour were built in an average of 36 months. That is 16 months from laying down to launch and 20 months from launch to completion.
- The 203 US submarines completed between Pearl Harbour and VJ-Day were built in an average of 11 months. That is 7 months from laying down to launch and 4 months from launch to completion.
- The 115 Japanese submarines completed between Pearl Harbour and VJ-Day were built in an average of 15 months. That is 7 months from laying down to launch and 8 months from launch to completion.
The first set is for Oct 1935, later set is for May 1942 - the last I have in the same/similar format. In the May 1942 set, I only included cruisers, 1620/1630-ton DDs and the first page of Fletchers. May 1942 data adds a column for ahead/behind contracted completion.
October 1935:
May 1942:
By popular demand the averages were.
American Treaty Cruisers
- 23 months from laying down to launch and 10 months from launch to completion for a total of 33 months to build for the 18 Heavy Cruisers.
- 25 months from laying down to launch and 17 months form launch to completion for a total of 42 months to build for the 9 Light Cruisers.
- 24 months from laying down to launch and 12 months from launch to completion for a total of 36 months to build for the 27 Treaty Cruisers.
- 32 months from laying down to launch and 17 months from launch to completion for a total of 49 months to build for the 12 Heavy Cruisers.
- 27 months from laying down to launch and 18 months from launch to completion for a total of 45 months to build for the 6 Light Cruisers.
- 31 months from laying down to launch and 17 months from launch to completion for a total of 48 months to build for the 18 Treaty Cruisers.
- The Japanese Heavy Cruisers took.
- 9 months longer from laying down to launch (32 months v 23 months).
- 7 months longer from launch to completion (17 months v 10 months).
- 16 months longer to build (49 months v 33 months).
- Which depending upon how you look at it means that it took:
- Japan 50% more time to build a Heavy Cruiser.
- And.
- The USA two-thirds of the time to build a Heavy Cruiser.
- Japan 50% more time to build a Heavy Cruiser.
- The Japanese Light Cruisers took.
- 2 months longer from laying down to launch (27 months v 25 months).
- 1 month longer from launch to completion (18 months v 17 months).
- 3 months longer to build (45 months v 42 months).
- Which is about the same.
- The Japanese Treaty Cruisers took.
- 7 months longer from laying down to launch (31 months v 24 months).
- 5 months longer from launch to completion (17 months v 12 months).
- 12 months longer to build (48 months v 36 months).
- Which depending upon how you do it means that it took.
- Japan a third more time to build a Treaty Cruiser.
- And.
- The USA 75% of the time to build a Treaty Cruiser.
- Japan a third more time to build a Treaty Cruiser.
The Japanese light cruisers are the Mogami & Tone classes, which were ordered as light cruisers, but completed as heavy cruisers or completed as light cruisers & rearmed with 8in guns later.
NOMI you are the absolute man.
And like i outlined earlier, the japanese CL situation is worse because iirc 2 of the Mogamis went straight back to the shipyards to be rebuilt after their ostensible completion date. And more time/space hogged rearming them. So while i just can't see the japanese matching the wartime US building rates, at least during the interwar years they could have had.
And like i outlined earlier, the japanese CL situation is worse because iirc 2 of the Mogamis went straight back to the shipyards to be rebuilt after their ostensible completion date. And more time/space hogged rearming them. So while i just can't see the japanese matching the wartime US building rates, at least during the interwar years they could have had.
That though is still a bad showing for IJN as most of the the US cruisers were formidable Clevelands and Baltimores, while the japanese ones were Aganos and Oyodos. But if they would have done better interwar, perhaps they would have had yard space to build and finish Niyodo and the 2 Ibukis, while still carrying out a more extensive CV building program.
Same with wartime DDs really, if the japanese up their game a bit maybe they could finish around 40 of them instead of just 31.
Is the first item on your list why the Japanese cruisers had lower rates of fire than American cruisers? Especially the triple 6" gun turrets on the Brooklyn & Cleveland classes.
I think I've seen that given as the explanation elsewhere on this board.
This post went unremarked until now!
Looking at the Kongo class, and with a late prewar second refit, they got a speed of over 30 kts!?!? If the Fuso class and Ise class were not only given this treatment, but lightened by a pair of twin 14" gun turrets, what could they see their speed increased to? This would give the IJN 8 old, 14" gunned battleships, but with speed increased to match the USN last 10 BB .
If the spare 8 twin 14" gun turrets could be reused on 2 new BB, what kind of speed could new ships be built with, while still armed with 4 twin 14" gun turrets each? These two new ships would give the IJN 10 14" gunned 'fast battleships'.
Let me ask this:
Given main armament of 8 X 14" guns...
Desired speed of 33 Kts (plus or minus 2 Kts)...
Total displacement would need to be somewhere between 25,000 - 35,000 tons.
Can anyone offer a design along these lines, so that these new notional IJN fast BB (built instead of the Yamato class) might look like?
A design with 31 kts speed, on 25,000 tons displacement would look like what?
A design with 35 kts speed, on 25,000 tons displacement would look like what?
what about a...
A design with 31 kts speed, on 35,000 tons displacement would look like what?
or...
A design with 33 kts speed, on 35,000 tons displacement would look like what?
And last but not least, can the Japanese 'leak' that the last two ships are actually the first of a 12" gunned class of BC, and thus reinforce the USN construction of the Alaska class ships?
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To add my small contribution to the issue of building times, the interwar carriers not covered by NOMI:
On average , Ryujo, Hiryu and Soryu took on average 38 months to build, that is 15 months to launch and 23 months to fit out.
Ryujo 17 plus 25 equal 42 months
Soryu 13 plus 24 equal 37 months
Hiryu 16 plus 20 equal 36 months
The US carriers took on average just under 40 months to build, that is rounded up 22.5 months to launch and 17.5 to fit out.
CV-4 Ranger 17 plus 16 equal 33
CV-5 Yorktown 23 plus 17 equal 40
CV-6 Enterprise 27 plus 19 equal 46
However, the japanese ships were smaller (Ryujo much smaller than Ranger), so these building times would only be acceptable if Ryujo was to be build as a sort of pre-Soryu design from the start. It seems regardless of whether the IJN gets or not a better ratio at the treaties, Ryujo is the key ship in giving KB more capability. If Ryujo is built as full size fleet carrier (as in same size and aircraft capacity roughly as Soryu) KB will have 7 such ships in 1941 regardless of other changes we contemplate ITTL.
On average , Ryujo, Hiryu and Soryu took on average 38 months to build, that is 15 months to launch and 23 months to fit out.
Ryujo 17 plus 25 equal 42 months
Soryu 13 plus 24 equal 37 months
Hiryu 16 plus 20 equal 36 months
The US carriers took on average just under 40 months to build, that is rounded up 22.5 months to launch and 17.5 to fit out.
CV-4 Ranger 17 plus 16 equal 33
CV-5 Yorktown 23 plus 17 equal 40
CV-6 Enterprise 27 plus 19 equal 46
However, the japanese ships were smaller (Ryujo much smaller than Ranger), so these building times would only be acceptable if Ryujo was to be build as a sort of pre-Soryu design from the start. It seems regardless of whether the IJN gets or not a better ratio at the treaties, Ryujo is the key ship in giving KB more capability. If Ryujo is built as full size fleet carrier (as in same size and aircraft capacity roughly as Soryu) KB will have 7 such ships in 1941 regardless of other changes we contemplate ITTL.
You are looking basically at a enlarged B-65 battlecruiser. The advantage would be of course they can be built quickly, and with large savings in materials, plus large savings in time/materials to build the new drydocks, on the other hand these ships can't really fight with US and UK new treaty BBs, but it can outrun them (except maybe Iowa class).
Would also mean the japanese somehow abandoned their BB line, which is very hard to make happen in any ATL. They would make good cruiser killers/raiders of course.
But really for an extra 10,000 tons they can have the 45,000 ton small Yamato, which would outclass the US and UK 35,000 ton BBs while staying in the ring at least evenly with an Iowa, and still save a lot of time and materials compared to OTL Yamatos.
As to the Fuso and Ises, rather than modify them further at great extra cost, materials and time (which i doubt Japan has), i would rather invest those resources in re-engining the 2 Nagatos with 127,000 HP engines which will increase speed to around 28 knots, ie as fast as the 8 gun modified Ise and Fusos will be, but much more formidably armoured and armed. The 8 gun Fuos and Ise at about 28 knots will not be much better than the Kongos in combat against any modern US and UK BBs. The same problem the italians encountered with their modernized old BBs, too much expense for a too little increase in capability.
So you have two 28kts Nagatos and four 45,000 ton Yamatos at 29-30 kts as the core of the BB fleet, which not only can face any western BB
confidently, but also are fast enough to escort the Kido Butai (in addition to the 4 Kongos).
That's my opinion anyway.
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For what it's worth according to Naval Weapons (http://www.navweaps.com/Weapons/index_weapons.php#Naval_Guns) . . .
United States Cruiser & Destroyer Guns
8.0in/50 Marks 9 to 16
3-4 RPG/minute Marks 9 to 15.
10 RPG/minute Mk 16 aboard the Des Moines class.
41° maximum elevation
6.0in/47 Mark 16
8-10 RPG/minute at 40°
5° RPG/minute at 60° but measures to increase this to 8-10 RPG/min were proposed.
40° designed maximum elevation, but increased to 60°
5.0in/38 Mark 12
12-15 RPG/minute on pedestal and other mounts lacking integral hoists.
15-22 RPG/minute on base ring mounts with integral hoists.
85° maximum elevation.
Japanese Cruiser & Destroyer Guns
8.0in/50 3rd Year Type Nos. 1 and 2.
3-5 RPG/minute for No. 1 Gun.
Except less than 2 RPG/minute in the Furutaka class.
4-5 RPG/minute for No. 2 Gun, depending upon the ammunition supply system.
4 RPG/minute in the Aoba and Furutaka classes.
5 RPG/minute in the later classes, which declined to 2-3 RPG/min at 55° and 2 RPG/min at 70°.
25, 40, 55 or 70° maximum elevation depending upon the type of turret.
6.1in/60 3rd Year Type in triple mounting on Yamato class battleships and the Mogami & Ōyodo class cruisers.
5-6 RPG/minute.
7 RPG/minute was the theoretical rate of fire,
but the ammunition hoists could only lift 6 RPG/min and the powder hoists could only lift 5 bags per gun/minute.
55° maximum elevation.
5.9in/50 41st Year Type in twin mounting on Agano class.
10 RPG/minute theoretical.
5-6 RPG/minute effective.
55° maximum elevation.
5.0in/50 3rd Year Type in single and twin mountings.
5-10 RPG/minute.
40-75° maximum elevation depending on the mounting.
Also slow elevation & training speeds and no AAFCS.
4.7in/45 10th Year Type.
10-11 RPG/minute maximum.
6-8 RPG/minute effective.
75° maximum elevation.
3.9in/65 Type 98.
15-19 RPG/minute.
90° maximum elevation.
Therefore, in rate-of-fire terms the IJN & USN 8in guns were about the same. However, the IJN light cruiser & destroyer guns were inferior. Plus the Japanese 5in gun was in a mounting with poor elevation & training rates and I think it's been mentioned earlier in the thread that Japan didn't have a half-decent light AA gun, let alone a good one.
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Japanese Treaty Cruisers (Revised)
IOTL Japan leaving the Treaty System at the end of 1936 allowed the IJN to complete the Tone class and rearm the Mogami class with ten 8in guns in 5 twin turrets. But if rate-of-fire of the Japanese 6.1in/60 gun & its mounting had been as good as the US 6in/47 gun & its mounting the IJN would have been better off keeping those ships original main armament.
The IJN might also have been better off rearming the older Furutaka to Takao classes with the TTL version of the 6.1in/60 gun & its mounting. The volume of fire would have been useful in the OTL surface battles and as an AA gun against lower flying targets, especially if Japan develops a VT fuse for them ITTL.
The Myōkō to Tone classes were also competed with or rearmed with a secondary armament of eight 5.0in/50 guns in four twin mountings. More of them might have survived to take part in the battle of Leyte Gulf had said guns & mountings performed as well as the USN's 5in/38 gun and its twin mounting.
The story so far . . .
- In that post the First London Naval Treaty allowed Japan to have 70% of the British Commonwealth's cruiser tonnage instead of 65% of America's cruiser tonnage which increased Japans "replacement tonnage" from 51,000 tons to 79,405 tons.
- That allowed Japan to build 8 improved Myōkō-Takao type cruisers armed with fifteen 6.1in guns under the First & Second Fleet Replenishment Programmes instead of the six ships of the Mogami & Tone classes that were built IOTL.
- That would have given the IJN 20 heavy cruisers at the start of the Pacific War instead of 18 and the USN couldn't build more cruisers in reply.
- Their 18 heavy cruisers & 9 large light cruisers absorbed the "replacement tonnage" in the USA's tonnage quota.
- The best they could have done was to build more Brooklyn or Cleveland class cruisers to replace the 4 oldest Omaha class light cruisers instead of the Alaska class.
- Either myself or someone else wrote earlier in the thread that as they were cheating on displacements anyway they should have cheated even more by building their cruisers & destroyers with larger & stronger hulls to avoid the time, expense & dockyard capacity of rebuilding them later on.
IOTL Japan leaving the Treaty System at the end of 1936 allowed the IJN to complete the Tone class and rearm the Mogami class with ten 8in guns in 5 twin turrets. But if rate-of-fire of the Japanese 6.1in/60 gun & its mounting had been as good as the US 6in/47 gun & its mounting the IJN would have been better off keeping those ships original main armament.
The IJN might also have been better off rearming the older Furutaka to Takao classes with the TTL version of the 6.1in/60 gun & its mounting. The volume of fire would have been useful in the OTL surface battles and as an AA gun against lower flying targets, especially if Japan develops a VT fuse for them ITTL.
The Myōkō to Tone classes were also competed with or rearmed with a secondary armament of eight 5.0in/50 guns in four twin mountings. More of them might have survived to take part in the battle of Leyte Gulf had said guns & mountings performed as well as the USN's 5in/38 gun and its twin mounting.
Great info compilation as usual. I'm always of the opinion that the Mogamis and Tones should have kept the 15,5cm guns in even as is configuration, that still means 50 percent more barrels and over twice as many shells lobbed at the enemy. This is the lowest hanging fruit.
The second lowest hanging fruit is if possible, better hoist designs so at least the guns as they are can fire to their theoretical max rpm.
The third is improved guns, at least the 15,5 cm and 12,7 cm ones, that are roughly equal to their US counterparts in rpm, training/elevation speeds, DP suitability etc. They did have a DP 12,7cm/50 the Type 1 prototyped for instance, so it could have been done.
The fourth and the most extreme one, is autoloaders for most/all the guns listed above. Given as you say the japanese were looking at every means to gain an upper hand, autoloaders could have given them just that. Could they have done it before the war? Of course that means fewer guns or bigger hulls or both, due to increased weight/complexity of the mounts, but one can imagine the deluge of fire they could have brought both in AS and AA engagements. And while at it, how about an automatic 8 cm Type 98 gun? Of course all this must be complemented by a 37/40mm autocannon as we've touched on previously. And of course a VT fuse for at least the bigger AA guns.
The second lowest hanging fruit is if possible, better hoist designs so at least the guns as they are can fire to their theoretical max rpm.
The third is improved guns, at least the 15,5 cm and 12,7 cm ones, that are roughly equal to their US counterparts in rpm, training/elevation speeds, DP suitability etc. They did have a DP 12,7cm/50 the Type 1 prototyped for instance, so it could have been done.
The fourth and the most extreme one, is autoloaders for most/all the guns listed above. Given as you say the japanese were looking at every means to gain an upper hand, autoloaders could have given them just that. Could they have done it before the war? Of course that means fewer guns or bigger hulls or both, due to increased weight/complexity of the mounts, but one can imagine the deluge of fire they could have brought both in AS and AA engagements. And while at it, how about an automatic 8 cm Type 98 gun? Of course all this must be complemented by a 37/40mm autocannon as we've touched on previously. And of course a VT fuse for at least the bigger AA guns.
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If the Japanese VT fuse programme costs anything like the Allied one, it will cost as much as 10 Iowas. So what will they cut in order to afford VT fuses?
There's also the point that since heavy AA didn't really knock down all that many aircraft anyway, improving its efficiency even seven-fold wasn't actually particularly valuable.
There's also the point that since heavy AA didn't really knock down all that many aircraft anyway, improving its efficiency even seven-fold wasn't actually particularly valuable.
1) No Yamatos, the steel could have been better used for carriers and anti-submarine vessels.
2) Talk to the German Naval Attache about developing a submarine strategy for going after merchant ships.
3) create a program for training lots of Naval aviators
4) an emergency merchant ship construction program.
5) take the reconsince job away from float planes and use a torpedo bomber modified to carry extra fuel. That would allow the Japanese to fully exploit their carrier based aircraft's superior range.
6) build more long range flying boats for reconnaissance.
2) Talk to the German Naval Attache about developing a submarine strategy for going after merchant ships.
3) create a program for training lots of Naval aviators
4) an emergency merchant ship construction program.
5) take the reconsince job away from float planes and use a torpedo bomber modified to carry extra fuel. That would allow the Japanese to fully exploit their carrier based aircraft's superior range.
6) build more long range flying boats for reconnaissance.