I feel that I must pause on watching football to give a few more details of Freedonia's position. As most of you know, Freedonia is positioned in the Indian Ocean and is descended from the kingdom of Queen Ranavalona https://en.wikipedia.org/wiki/Ranavalona_I
, who was instrumental in creating a navy with British assistance. Freedonian warships probably require similar range to British or Japanese ships but are not expected to carry out trans-Pacific operations.
One of Freedonia's possible strengths are its amazing fortune tellers, one of whom, an elderly lady with no military experience, nonetheless appears to know some details of the future via a crystal ball. In fact, she denies knowing what actually happened to battleships in the future but claims that her ball gives her glimpses of a weird thing from the future called the internet where all sorts of claims and unreliable information about battleships can found. On the basis of this unreliable data, she tells me that Freedonia will side with the Allies in something called WW2.
Apparently, Freedonia will enter the war in 1942 after receiving a huge American bribe and may send one or more of Freedonia's battleships to help defend the Netherlands East Indies, where they may be attacked by something called the Kido Butai, possibly at Darwin. At the end of 1942, another ship may engage an enemy called Tirpitz in the Battle of the Barents Sea (oddly it seems that Freedonia's existence will speed up Tirpitz's refit). Either the same ship or another of its class will be hit by something called a Fritz-X off Italy in 1943. Finally, she believes that our battleships, if any survive, will take part in a British led invasion of Sumatra in early October 1944 https://en.wikipedia.org/wiki/Operation_Culverin
and will be opposed by Japanese battleships under Kurita sailing from Singapore which are equipped with something called the Type 91 shell.
I should mention that we hope to invest about 160 million Dollars in building battleships, which my fortune teller says will buy three or four King George V or Lion class or two Bismarcks, North Carolinas, South Dakotas or Yamatos. However, apparently Iowas cost about 100 million and Montanas may cost even more. Unfortunately, I do not know why the costs are so different. The fortune teller speculates that King George V and Yamato, which cost about the same per ton, are mostly riveted and have much less redundancy in things as diverse as electric generators, pumps or fire control. It is also clear that Ducol is much cheaper than STS but that does not account for Bismarck's cost although the slightly artificial $/RM ratio may have an impact.
The last generation of battleships all represent highly optimized designs. However, it seems legitimate to ask whether use of the best "available" technology could improve one of these designs. Thus, Freedonia has obtained a sketch of the design of Yamato and I would be interested to know what the cost would be if we built the hull out of welded ST 52 to try to save some weight, fitted American machinery to try to save space (unfortunately Montana's 172,000 shp plant isn't obviously much smaller than Yamato's older machinery but clearly generates more electricity as well as giving more power) and fitted a British main armour belt.
One point of using narrower machinery is that it would give us room to improve the obvious weakness of Yamato, which was its protection against torpedoes http://www.spacecruiseryamato.com/ijn/a ... /heel.html
. Given more space, the simplest way to avoid the weakness at the joint of main and lower belt would be to have the lower belt continuing the upper belt's slope, so that amidships both are at 20 degrees rather than the lower belt being at 8 degrees. The connection can then imitate that in South Dakota or Iowa. The requirement is that the width of the machinery is approximately 3 metres less. Unfortunately, the lower belt is still nearer to a torpedo explosion than Iowa's lower belt because Iowa's whole belt is internal and Iowa's system did not perform perfectly in tests.
Alternatively, one could separate the main and lower belt as in the Montana Class. This gives better protection against torpedoes (in fact Montana could have almost certainly survived significantly more hits than the similarly sized Yamato or Musashi) and armour could ride on the torpedo bulkhead to stop shells passing below the main belt. The main cost is extra weight. The upper belt is no longer supported by the lower belt but needs to be supported to resist either shell hits or explosions and the torpedo bulkhead or lower belt has to connect strongly to something above. Yamato did not have a structurally significant lower deck below the main armour deck with only 8 mm or 9 mm decks at varying heights. Thus, either a strong lower deck must be added or the torpedo bulkhead must extend to the main armour deck. If the new bulkhead were the same 45 mm thickness as those of Bismarck and had to go up 6 metres, it would add around 600 tons for just that upward extension. Then we would have to decide how much armour to fix to the bulkhead, assuming that we add face hardened armour rather than making a complicated tapered homogeneous plate. The Vickers Cemented armour of Yamato's lower belt was fixed to a 14 mm Ducol plate. If we use 3 cm thinner armour fixed to 45 mm of homogeneous armour, we will have less resistance to Type 91 shells. Thus, again we must chose between reduced protection and increased weight. Finally, note that the magazines must also be narrower and thus either longer or deeper, so that again we are scrabbling to save compensating weight.
At this point, we might ask if the Japanese Navy was justified in fitting such strong armour to stop underwater hits. Clearly they knew more about the Type 91 shell than anyone else and the speed after passing some distance underwater would not be too hard to measure. Thus the estimate that a shell lost half its initial velocity after travelling 100 calibres was probably not too bad if using suspiciously round numbers. However, possibly the shell would be yawed by the water and estimates of its penetration from firing shells at reduced velocity through air at plates might be optimistic.
Nonetheless, there is no doubt that a Type 91 shell could have penetrated into the citadel of any non-Japanese battleship. For example, the initially 8.5" lower belt of Montana quickly reduces to 3.75" and then stops leaving about half the target above the triple bottom defended only by 25 lb and 30 lb bulkheads. A shell from Yamato at 20,000 yards entering the water at 15 degrees and landing 20 to 40 metres short would probably defeat the bulkheads and longer range would move the window closer without narrowing it too much. The reason that the USN was unconcerned about that danger was that a shell with a USN 0.035 second fuse would have exploded before striking a ship at that depth. The 0.4 second Japanese fuse would allow a shell that did not hit thick armour to pass through a ship before exploding but would also allow hits below 5 metres (as would a defective shell from Bismarck).
I realise that Dave would have preferred Freedonia to take the H39 design as a starting point and I can see the case. However, Germany seems to have concluded that the Bismarck or H39 armour scheme, whilst an efficient use of weight against shells by using yaw, was not effective against bombs and thus the H41 project had a much thicker main armour deck http://www.kbismarck.org/forum/viewtopi ... =13&t=8281
Thus, we are currently exploring modifications of the basic Yamato design with its thick main deck, especially as our fortune teller suggests that bulbous bows and transom sterns may become standard practice on large fast warships.
Yamato has a very high freeboard amidship (see https://www.flickr.com/photos/27417638@N07/4181515847
which seems to be a copy of the illustration from page 52 of Skulski's Anatomy of a Ship - The Battleship Yamato). I am hoping that Freedonia may be able to follow German ideas with a continuous 50 mm or 80 mm weather deck and a fairly thick outer shell to allow us to use much thinner main barbettes, which are 560 mm in Yamato, and perhaps use a slightly thinner main deck especially for the angled sections, which may be 230 mm on 14 mm, with the additional thickness only needed to resist shells. If this does not cost significant weight nor lower the GM too much, we will have greatly strengthened our protection against bombs dropped by dive bombers as armour piercing bombs will not kill the anti aircraft gunners whilst general purpose bombs will not penetrate the weather deck.
Of course, we will still have maintain an angle to an enemy to prevent the 41 cm belt of hopefully British face hardened armour being penetrated and we may need to maintain a similar angle at long range to protect the angled sections of main deck, which will be wider but less slopped as the torpedo protection becomes wider.