Alternate warships of nations

Driftless

Donor
I often hear negative comments about the dubious utility of WW1 and later casemate mounted secondary guns, especially those mounted towards the forward part of the ship. The most common complaint is the effect of weather and sea conditions that would limit their use in battle. The second most common remark (I hear) is the limited traverse and elevation for those weapons.

1. Was there a ship, or class of ships where casemate mounted guns worked in actual practice, compared to designer hopes?

2. If those mounts were so doubtful, why did they linger in use for so long? The problem was noted early on.
 
I often hear negative comments about the dubious utility of WW1 and later casemate mounted secondary guns, especially those mounted towards the forward part of the ship. The most common complaint is the effect of weather and sea conditions that would limit their use in battle. The second most common remark (I hear) is the limited traverse and elevation for those weapons.

1. Was there a ship, or class of ships where casemate mounted guns worked in actual practice, compared to designer hopes?

2. If those mounts were so doubtful, why did they linger in use for so long? The problem was noted early on.
The problem isn't necessarily casemate guns themselves, it's that they were mounted in the hull below the main deck. Ships that had the casemates mounted in the superstructure, such as the later Standards or the British ships with 4" guns, encountered far fewer problems with seakeeping.
 
Hiyo-class aircraft carrier (commissioned 1941)
Imperial Japanese Navy
Ships: Hiyo, Junyo


Part One
The Hiyo-class aircraft carriers were possibly the most controversial ships in the maritime history of imperial Japan. The entire idea of converting into carriers two active-service battleships, still in excellent condition and ripe for modernisation, at a time when the IJN was still very much focused on the supremacy of the battleship and the idea of Decisive Battle, flew in the face of established wisdom. As it turned out, however, the two vessels would be some of the most important ships of the Pacific War.

The Hiyo and Junyo were originally the fast super-dreadnoughts Nagato and the Mutsu, respectively; the only ships of the 8-8 fleet programme to make it onto the war in their intended forms. Commissioned in 1920 and 1921, by 1934 they were in good shape but were due for a major set of upgrades. From surviving historical documents, installing these would probably have taken until 1936, and involved the reconstruction of the forward superstructure, lengthening of the stern, installation of torpedo bulges, increased armor protection on the turrets and deck, and many other beneficial features that would have greatly increased the combat efficacy of the two battleships.

However, when astute Japanese naval planners looked at the manner in terms of the grand scheme of things, this did not seem like such a good idea. If the Japanese navy was to get into a major war with either Britain or the United States, its battle-line would be outnumbered from the start. Modernising the Nagato and Mutsu would only yield ships that, at best, were somewhat superior to the US Colorado-class or the British Nelson-class - ships with specifications not powerful enough to ensure success in any future conflict. In contrast, from 1934 onwards, various design studies were emerging from the pens of Japanese naval architects for battleships that would provide these specifications, which would eventually develop into the Yamato-class, the pinnacle of the Decisive Battle mentality. If these ships, of which at least two were projected and several more considered, could handily provide victory, the reasoning went, there would be no need to modernise the Nagatos. This logic was indisputably sound. Despite serious efforts from the IJN's 'gun club' to cut down this scheme before it was born, it began to gain shape and vitality.

Yet the hulls of the two ships were still in good condition, and, as the idea gained credence, Japanese naval planners knew that the two ships had similar designs to the Tosa-class battleships, one of which, the Kaga, had been successfully converted into an aircraft carrier and, in 1934, was just about to start a major refit. Comparing the two classes, it gradually became clear to the Japanese that, based on their experiences with the Kaga, they could successfully convert the Nagato and Mutsu into fleet carriers. This would be done once Japan had pulled out of the various naval treaties, and the tonnage limits they entailed. Thus, for a few more years, Nagato and Mutsu would remain in service, although care would be taken to preserve their machinery in particular.

In due course, Japan denounced the 2nd London Naval Treaty in 1937, and started construction of the Yamato-class battleships and Shokaku-class aircraft carriers. Simultaneously, arrangements started to be made for the conversion of the Nagato sisters; they were decommissioned in 1938, and their eight 16.1" turrets were removed and carefully stored, along with their armor plating. These materials, along with the eight 16.1" turrets left over from the building process of the 8-8 fleet, would later be used in the construction of the four Kii-class fast battleships, which were all laid down in 1939 and were to form the backbone of the future IJN alongside the Yamato and Musashi.

In 1939, despite the continuing protests of many naval officers, the conversion was able to begin, Nagato starting in March and Mutsu starting in June. This entailed the lengthening of the hull, the addition of a flight deck and arresting gear, the construction of a rather large starboard island with an integrated stack - a first for a Japanese carrier - the creation of two superimposed hangars, and replacing the old mixed-firing boilers with new, pure oil-firing units that, alongside new propellors, allowed the ships to easily reach 28 knots. The main AA armament would now consist of six twin 5" guns, three mounts on each side, along with various 25mm cannon emplacements and some machine guns. They would carry an airgroup of 57 aircraft when commissioned in 1941, although this number would vary over the course of the Pacific War.

The conversion was completed in early 1941, and the two ships were renamed Hiyo and Junyo. Upon completing their trials and work-up in September, they were assigned to Carrier Division 6 of Chuichi Nagumo's 1st Air Fleet, or Kido Butai, and would be commanded by Rear Admiral Kakuji Kakuta, not an aviator but still deemed suitable for the post due to his experience as commander of Carrier Division 3. Alongside the rest of 1st Air Fleet, Hiyo and Junyo, also known as the 'Hawk Sisters', would train for the upcoming, complicated Operation Z.

On December 7th, 1941, Operation Z began. The attack was split into two stages. In the first stage, Akagi, Kaga, Hiyo and Junyo attacked the base at Pearl Harbour itself, focusing mainly on the cruisers and destroyers and causing substantial damage. In the second stage, as Admiral Kimmel's fleet of seven surprised but intact battleships made its way into the open ocean to find the Japanese ships, they were set upon by Soryu, Hiryu, Shokaku and Zuikaku, and later by Carrier Divisions 1 and 6 as well. In the repeated air attacks, Tennessee, California and Oklahoma would all be sunk, and Arizona and Nevada would be crippled, to be later finished off by Japanese surface units and submarines. Maryland and West Virginia would only survive thanks to some timely support from planes from the carrier Enterprise, who, although they took severe casualties, were able to distract the Japanese attackers long enough for the battleships to make a getaway. Pearl Harbor was to prove one of the worst defeats in the history of the US Navy, and cemented the importance of the carriers into Japanese naval mythology.

Unfortunately for the IJN, Operation Z had found no aircraft carriers in Pearl Harbor. This meant that the bruised US Pacific Fleet could still call upon Lexington, Saratoga and Enterprise, and later Yorktown and Wasp, along with the rookie sisters Hornet and Constellation to fight. In the meantime, however, they could do little to stop the advance of the Kido Butai. Within months, Nagumo would sweep through the southern and western Pacific, sowing death and destruction in his wake. By March 1942, as it dropped anchor in Staring Bay, Java, Kido Butai had helped Japan seize one of the largest empires in history, destroyed hundreds of Allied planes, and sunk many hapless Allied warships. The force seemed invincible and unstoppable.

It was about to get a lot harder, however...

What's the operational top speed of these, post-conversion?
 
I often hear negative comments about the dubious utility of WW1 and later casemate mounted secondary guns, especially those mounted towards the forward part of the ship. The most common complaint is the effect of weather and sea conditions that would limit their use in battle. The second most common remark (I hear) is the limited traverse and elevation for those weapons.

1. Was there a ship, or class of ships where casemate mounted guns worked in actual practice, compared to designer hopes?

2. If those mounts were so doubtful, why did they linger in use for so long? The problem was noted early on.
Maybe the Connecticuts.

Casemate guns take less hull and deck work space and weigh much less per station than barbette and turntable guns of similar size.
 
Same as for Kaga, so 28 knots. Historically the Tosa and Nagato designs had pretty similar baseline top speeds of around 26 to 26.5 knots.
Better candidates are Ise and Hyuga. By the time specified, the IJN knew about the hogging and the banjo effects of too many guns /'barbettes along too long a hull. So if anny BB gets the buzzcut and flattop special, those two will be nominated.
 
Better candidates are Ise and Hyuga. By the time specified, the IJN knew about the hogging and the banjo effects of too many guns /'barbettes along too long a hull. So if anny BB gets the buzzcut and flattop special, those two will be nominated.
But what about Fuso and Yamashiro? My intention was that those four could be kept together as a homogeneous, 2nd-line division. The Nagatos are an odd fish when it comes to the IJN battle line: they aren't as old as those guys, nor as they as fast as the Kongos, nor are they, well, as chunky as the Yamatos.
 
1. Was there a ship, or class of ships where casemate mounted guns worked in actual practice, compared to designer hopes?
The problem isn't necessarily casemate guns themselves, it's that they were mounted in the hull below the main deck. Ships that had the casemates mounted in the superstructure, such as the later Standards or the British ships with 4" guns, encountered far fewer problems with seakeeping.
Is the other issue not that all the designs are based off per war (WWI) Saling and training, ie far too much time only spent out in daytime & good weather rather than a realistic evaluation of North Sea winter conditions?

That and casemounts came from earlier slower ships where the issues would be less and would affect both sides the same anyway.
 
But what about Fuso and Yamashiro? My intention was that those four could be kept together as a homogeneous, 2nd-line division. The Nagatos are an odd fish when it comes to the IJN battle line: they aren't as old as those guys, nor as they as fast as the Kongos, nor are they, well, as chunky as the Yamatos.

Short version? The Ise and Hyuga were garbage as battleships when Hiraga designed them.
That left the idea of rebuilding the four 14 inch ships as semi-carriers. Originally, it was planned to rebuild all four ships (they were very unsatisfactory battleships; the distribution of turrets along the ship's length gave an awful lot of magazines to hit and the 1930s rebuilds had been carried out without proper structural analysis causing excessive stress). However, shipyard congestion meant that only two battleships could be converted, so the Fuso's were dropped from the program.

The reasons for the selection of the more modern Hyuga's for the conversion were mostly gunnery. The Japanese had increased the elevation of the ship's guns by deepening the gunwells in the turret rather than raising the trunnions. Hull depth aft had prevented this for the aftermost turrets so they had severely restricted elevation, at long range reducing the gunpower of the ships by a third. Also, Hyuga had had a turret explosion on 15 May 1942 that had destroyed X turret - damage that still had not been repaired. Although Ise and Hyuga were slightly faster than their older cousins, the difference was not enough to be really significant.
"But what about Fuso and Yamashiro? My intention was that those four could be kept together as a homogeneous, 2nd-line division. The Nagatos are an odd fish when it comes to the IJN battle line: they aren't as old as those guys, nor as they as fast as the Kongos, nor are they, well, as chunky as the Yamatos."

Fuso and Yamashiro? Buzzcut them, too. Same reason. Garbage battleships could make passable 2nd line flattops. If one is going this route in 1936. (or 1932 when the modernizations begin), then one might as well give the Fusos the Hyuga treatment and make all four a carrier battle group. All or nothing.
 
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Better candidates are Ise and Hyuga. By the time specified, the IJN knew about the hogging and the banjo effects of too many guns /'barbettes along too long a hull. So if anny BB gets the buzzcut and flattop special, those two will be nominated.
This is actually what I have happen IMTL, to the entire Fuso, Ise group in fact. Those ships were not very good and the Japanese knew it. Better to get four alright carriers and keep the guns for future use than throw money to make a terrible battleship into a less so design.
 
This is actually what I have happen IMTL, to the entire Fuso, Ise group in fact. Those ships were not very good and the Japanese knew it. Better to get four alright carriers and keep the guns for future use than throw money to make a terrible battleship into a less so design.
I think it would take far more changes to the ATL to turn four battleships into carriers than two.
 
Same as for Kaga, so 28 knots. Historically the Tosa and Nagato designs had pretty similar baseline top speeds of around 26 to 26.5 knots.

OK. That makes sense.

Assuming it can get the trained pilots to man these carriers, an IJN that starts the war with 8 fleet carriers (even if half of them are new and still need some working up) rather than 6 is going to make Nimitz's life a little more interesting in the first year or two of the war.

Of course, once the U.S. gets wind of this, I have to think there will be a response. Which I think would take the form of at least one more extra Yorktown to go along with Hornet. [This would likely be named Constellation.] Or maybe two? Though it might not be ready quite as fast as Hornet, depending on when U.S. intel learns of it.

I have not considered the British response. They had less slack in shipyard capacity (and Chamberlain's purse) to work with. Others here more familiar with the subject may have something useful to say here.

By the way, it is interesting to think about an 8 carrier strike on Pearl Harbor, and it is not *impossible*; but from what have read of the IJN PH planning, I really tend to think that the extra two carriers would be used elsewhere -- probably, to help cover the Malaya landings. This, too, would be enormously useful to Yamamoto.
 
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Of course, once the U.S. gets wind of this, I have to think there will be a response. Which I think would take the form of at least one more extra Yorktown to go along with Hornet. [This would likely be named Constellation.] Or maybe two? Though it might not be ready quite as fast as Hornet, depending on when U.S. intel learns of it.
It would have to be much earlier than the Two Ocean Navy Act.
By the way, it is interesting to think about an 8 carrier strike on Pearl Harbor, and it is not *impossible*; but from what have read of the IJN PH planning, I really tend to think that the extra two carriers would be used elsewhere -- probably, to help cover the Malaya landings. This, too, would be enormously useful to Yamamoto.
I do not know if the IJNAS flight schools or the Japanese aviation industry could supply the 400 additional fliers or 200 aircraft?
 
OK. That makes sense.

Assuming it can get the trained pilots to man these carriers, an IJN that starts the war with 8 fleet carriers (even if half of them are new and still need some working up) rather than 6 is going to make Nimitz's life a little more interesting in the first year or two of the war.

Of course, once the U.S. gets wind of this, I have to think there will be a response. Which I think would take the form of at least one more extra Yorktown to go along with Hornet. [This would likely be named Constellation.] Or maybe two? Though it might not be ready quite as fast as Hornet, depending on when U.S. intel learns of it.

I have not considered the British response. They had less slack in shipyard capacity (and Chamberlain's purse) to work with. Others here more familiar with the subject may have something useful to say here.

By the way, it is interesting to think about an 8 carrier strike on Pearl Harbor, and it is not *impossible*; but from what have read of the IJN PH planning, I really tend to think that the extra two carriers would be used elsewhere -- probably, to help cover the Malaya landings. This, too, would be enormously useful to Yamamoto.
Yup, you got it right about the Constellation, and in this ATL it is ready a bit after Hornet. We'll see what it gets up to soon...

The British response? Can the economy even handle anything along those lines?
 
Yup, you got it right about the Constellation, and in this ATL it is ready a bit after Hornet. We'll see what it gets up to soon...

The British response? Can the economy even handle anything along those lines?
Britain could probably squeeze in a couple of unarmoured fleet carriers built in civilian yards if pushed.
 
The British response? Can the economy even handle anything along those lines?

The problem is, by 1938 it was already gearing up, effectively in Year One of a rearmament program. They need so many things, and Germany is a hell of lot closer than Japan is.

My gut check is a 50/50 chance Chamberlain agrees to add a third Implacable deck for the 1939 or 1940 estimates. Not sure which yard. Or maybe the pleas from Lionel Bond for more fighters in Malaya get a little more favorable hearing. That would be easier and cheaper to do.

Britain could probably squeeze in a couple of unarmoured fleet carriers built in civilian yards if pushed.

That's not a bad thought.

P.S. I tend to share the sense of others that the Ises would make better candidates for carrier conversions, If the IJN is really going to pursue that in 1936-38. The problem with them, of course, is the speed, since with what they had after rebuild would probably only make 26 knots as buzzcut flattops, and that is just not good enough for a *fleet* carrier; the propulsion plant makeover would have to be more extensive. That could make the whole project more expensive, and would tie up some scarce resources. It is the sort of consideration which, on top of the IJN Battleship Mafia, makes the whole thing tough to find a plausible point of departure for.
 
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