I long time lurker of this site I thought it about time to jump in. I like alternative histories based on twenty-twenty hindsight with the now declassified knowledge of the rivals plans along with seeing how technology has gone. It would be fair that the idea battleship with hindsight would have been an aircraft carrier task force
I do find it rather shallow comparing design from say 1933 that appeared on the seas in 1939-40 to designs that first sailed in 1944 or even later so like the idea that designs are considered in the context and ability of technology existing in the period that they were designed and constructed else the last of the USA battleships, cruisers and carriers would be the winners of any debate but back in 1940 they were at best pencil on paper. Also consideration needs to be given to the industrial capacity that existed so yes having a fleet of Yamato's would have been cool but no country apart maybe from the USA could afford them. Also thought needs to be given to political considerations and naval treaties as breaking the rules big time would mean your rival would quickly follow suit. British superiority in 1914-18 war was due to upping the size of battleships to 15" and having the capacity to build them in large numbers so the German battle line was faced by a larger number of bigger ships so things were not going to look good for them. I like the technological force multiplier as good ship design can turn the tables on apartently larger and more powerful ships and fleets. So that is where I will begin.
Now the historical fiction to build such a design. Assume a German naval officer of 1st World War of Germany took advantage of the great depression to ride into power on nationalism in 1930 and managed to get onside the disenchanted Germans to the extent that a particular corporal did not have the ready market for his ideology so decided to concentrate on painting instead. This person planned a rematch of 1914-18 but with the view that tactics, organisation, and technology was going to be the force multiplier to win through. This meant a short war of say a year as in longer wars the side with the greater industrial strength will only get stronger. What would be the ideal battleship design?
The operating naval treat suggest guns bigger than 14" were going to spark an arms race that Germany could not win so to hold the peace and after hard negotiation permission is sought and gained for Germany to build one battleship per year from 1933 onward. The project would be sold to Britain and co as a well balanced design of around 28 knots, 35,000 tonnes standard displacement and say 9 x 14" guns. The French would believe that their design out guns it and the British would see the existing fleet of 15" 16" ships more than a match with the newer 14" vessels having more fire power and "best of British design". The USA would not be worried greatly as their 12 x 14" designs would out gun the German design and also carefully designed them to be upgraded to 9 x 16". Ok, our German leader is not so worried by rules, merely how much he can cheat without having his hand called. The vessel will actually be designed as 40,000 standard tonnes and be say 750' long with a beam of 100' and the guns 14" but be 55 high velocity specials with a 16" by 48 coastal gun been designed along with a 16" x 53 one for the bigger class to follow. If this sounds a bit like the USA then it is because it is ripped off from their thinking. Instead of replacing the 14" x 4 turrets the idea is to drop in the 16" x 48 guns down the track. Our German leader is an adherent to high M/V or heavy or better still both fast and heavy shells are the way to go so imagine the Scharnhorst's nine 28 cm (11 in) (in fact, 28.3 cm (11.1 in)) specification up to 14" so around 900 metres per second so muzzle wear would be high and the idea is that 16" would fire a heavier shell of say 1,000 kilograms at say 800 metres per second with the fall back position being say a 1250 kg shell at what ever speed the turret could handle, so somewhere between South Dakota and Iowa class performance. Again idea stolen from the USA battleship play book. Fire rate somewhere between two to four rounds per minute. The German large guns at least on paper could cycle faster than their rivals so if I got three rounds per minute I would be a happy designer. Maximum elevation would be 45 degrees to get the best range and play with the idea of using them against aircraft. Ok it will not work but this is 1930 and megalomania is rife amongst the political elite. Radar would guide them in 1936 onward as I would hope that my leader would have the same capacity as understanding the ability of Radar as a very capable British RAF officer had. Germans actually had a slight lead in Radar so hopefully by 1940 over the horizon shooting would be available and that is where the range would count. Until then high velocity would better suit the dark and stormy seas of the Atlantic when used by optical range finders. Placement is two turrets at the front and one at the rear. The rear one would be high enough to enable the rear deck to be dropped past the turret and used to launch and recover aircraft. Bit like the Yamato but not as awkward looking as the Italian solution so say half way between the two front turrets for height.
Next is secondary guns. Big headache here. The USA 5" 38 for manual handling is almost ideal but that assumes you have plenty of cruisers to take out those pesky torpedo attacking destroyers, light cruiser and even the 8" ones commanded by glory hounds. The 5" would struggle against the 6" and 8" cruisers and swinging the big guns at them would leave your opposite number the freedom to send you to battleship Valhalla. For better or worst I would go with 155 guns of similar performance to the Japanese but aim for the fire rate of the Tiger, say 20, ok 10 rounds per minute is what I would probably wind up with and would accept this. Configuration is where my rather warped thinking comes into play. I like the idea that sharing a standard design across a range of ships so would aim for three three gun turrets down each side with the one in the middle being superfiring position. Such guns would appear on my light cruisers. The turret at the front and the back would be a deck level so three turrets for weight would comparablde with say four or five 140mm two gun turrets. Classic example of going for more guns in fewer turrets. The Yamoto and the French use triple six inch guns. The configuration would mean over most side arcs at least two turrets could engage a target. The elevation would be say 75% and the designers told no beer will be served until they can track as fast as say 300 mile per hour aircraft. So a torpedo side on attacking Swordfish would be having 1.5 shells per second lobbed at them while a light cruiser on a torpedo run would be engaged from over 25,000 metres inward. MV would be around 900 m/s and shell weight 55 to 60 kilograms. Yes such a design would push 1930 technology but possible for a country renown for quality engineering. So 6 triple mounts all up.
Third line of defence would be 3" dual mounts optimised for aircraft with some ability to fend off a destroyer. MV would be 1000 m/s as I am looking for an anti-tank weapon for my yet to be announced Panther tank. Long barrels are in so 77 x 60 gun. Looking for rate of fire of 30 rounds per minute that giving each turret the ability to achieve one round per second at an incoming aircraft. I would put two turrets forward and back in a superfiring position over the main guns nestled under the range finder. On the other side of the bridge and rear conning tower would be one turret with a turret either side of the funnel giving a total of ten turrets (maybe even twelve) and twenty (twenty-four) guns . More than enough fire power to fend of a British carrier attack, assuming good fire control. I mentioned Radar earlier did I not?
Final line of defence would be automatic 37mm Bofor type guns in shielded mounts. I would have a single funnel ship so right on top in between the funnel and the bridge and funnel and rear conning tower would be a quad setup. Where else possible I would mount twins so can not give the exact number so lets say two quads and a few twins. MV would be 1000 m/s so consider an automatic version of the standard hand loaded gun used by the Germans. These guns would be full self contained from the main ships systems so easy to placed where space exists. All lager guns would have feeds from under deck magazines. I am not a fan of revenge much preferring winning so such a weapon should be able to take out a plane before it has delivered its load, Rate of fire lets say a burst mode of 240 per gun but would be happy with WW2 Bofor rate of fire given the faster shell proposed. Such guns would be trainable on surface targets such as the stray sub or torpedo boat. By all accounts they made a mess of the Sydney (light cruiser) killing the people in the bridge such as the Captain so might just muck up a close in torpedo attack.
For completeness I would have a few 15mm single machine guns strategically placed to fend of commando type raids and give a bit of moral support against a stray aircraft.
The next thing is range finders. Like the idea of designing mounts that can double as Radar and optical range finders. Also experience has shown that a blinded battleship is a historical foot note so hence having four. Two positioned as per the Bismark and Hood and two mounted up high like the Yamato. This means all main turrets could be directed against three separate targets, something that the German Navy would likely need much more than a larger fleet. Also would allow redundancy plus ability to direct the secondary batteries given that the 155mm gun would be able to shoot to the horizon. The front top and rear main turrets would have range finders as well as fall back. Experience suggest that the range finders on the front turret just do not work. The two centre superfiring 6" turrets would have range finders that could link into central firing control. Yeap, over kill but necessary given that the ship is likely to operating alone or with limited support so being blind means sunk. Four, two each side aircraft gun directors would be used as well as the top of the bridge and rear conning tower range finders been consider to hold emergency ones. Such mounts would be equipped with Radar from 1936 onward. It would be a bold decision in 1933 to make the mounts capable of handling the extra load but I would call it design over engineering with later ships being designed to handle Radar positions.
Fire control systems. Centralised with forward and rear positions under the extreme forward and rear range finders. Ideally low down and armoured protected and likely below deck armour. All guns down to three inch under central fire control. The 37mm would be local fire control but might consider good communications and maybe central control but we are talking 1930 electronics. The crews would be trained to watch for the 6" and 3" puffs and be ready to take on what gets through. I would aim for a digital computer using valves or relays. Cheating you say? Well a German maths student invented such a thing so part of my war preparations would be trolling the Universities looking for ideas like this. All else fails back to 1930 technology but with a strong objective of been able to direct as many guns as possible and quickly as possible on a target with my chief fire control officer been able to pick the most dangerous threat.
Armour would take advantage of decapping plates and be inboard and sloping outward thus giving space for a multiple wet and dry torpedo protection systems. The main belt would merge into the final torpedo protecting plating. Yes trick to match a hard shell defeating armour with a flexible shock resistant armour so tongue and grove matching along with any other trick would be sought. The who aim is to make the ship resistant to 15" shells as that is what would likely be aimed at her. Special care would be taken to make the magazines resistant to 16" shells of say 16" L53 type if not a theoretical 18" shell. In fact spare weight would be put into deck and magazine armour with any trick such as decapping plates used. Deck would be as strong as possible to resist bombs and would aim for a 250 kg minimum but would like it to be 500 kg. I would use armour as a structure material as well so be looking for creative designers like Japanese cruiser designers. Ok it is my designed and I decided that conning towers(bridge area and rear) are to only be protected against destroyer and light cruiser non armour piecing shells as per British practice. I hear the rush of the USA readers heading for key boards. Everything I have read indicates that the British ships were not compromised by such a decision and such strong conning tower armour often did not work and besides even if did I doubt if people inside would be much use during the battle if clobbered by a large shell. My main fire control areas is where I would put the Admiral and third most senior officer. The Captain would likely be hanging of the highest point anyway, or should be. In fact where was the Japanese Admiral of 1906? Yeap, outside the conning tower getting the best view. The Captain of the Prince of Wales I believe was standing on top of even the lightly armour position. The British designers likely knew that at Jutland many captains were perched where the best view was so armour in a conning tower apart from fending of a five inch destroyer shell or long range 6" or 8" shell is wasted. To me it is a no brainier to protect the magazines at all cost as nothing quicker than a shell in the magazine means game over for everyone where losing the captain is sad but I would hope that my Admiral in the flag ship would solider on or my second in command would rise to the challenge.
Torpedo protection has been touched on but I would aim for South Caroline or better standard with the Montana being the objective given the narrow stated beam of one hundred feet compared to the broader beam of the never built USA ship. Any designed must resist 18" air dropped torpedos and have a chance of resisting a air dropped 21" torpedo. Ok the Rodney would win out along with the Long Lance but if the Rodney or Nelson got close enough to hit with a torpedo I think that the game would have been up long before that.
Propellers and steering. Four shafts would the the go with the outer two extending past the inner two providing protection against torpedos for the inner two. Ok armour around the shaft to avoid the POW issue and my ship must be able to steer on propellers or secondary rudders. Yeap explosive bolts or some means to drop a sticking rudder would be 101 for my battleship designer.
Propulsions is the last point. Love high pressure steam but 1933 it is not ready. Range and speed are two critical components of my consideration given once a ship has left German ports it had no chance of refuelling at a friendly port. The design must faster than the Nelson, Rodney and even the newer KG class so thirty knots under fouling and mechanical failure is the goal so looking at 140,000 to 160,000 SHP to do this given a 7.5 hull factor. Assume a bulb bow and all the tricks used on the Yamato and Normandy Ocean liner. Yes diesels is where I am heading but not any diesel. You have low, mid and high speed diesels so to get the performance you are looking at a high speed diesel. Cheating again the with timeline I predict from the critics? No, my inspiration is the Napier Deltic diesel which is based on the German Jumo diesel. Imagine a shaft running through the centre of the engine with hydraulic clutch connecting and disconnecting the engine. The engines are made up of three blocks that bolt together so the engine can be removed from the shaft. The design would actually be four banks of horizontally opposed pistons with eight cylinders in each bank giving 64 pistons per engine. I would not be looking at 4,000 rpm so can use bigger bore and might get away with a engine capable of 1200 rpm producing enough horsepower to rival for weight and space a high pressure steam setup. The Deltic diesel was used in naval vessels and was much more powerful than other high speed diesels. Lets say four shafts of 40,000 SHP should give enough speed to get to 30 knots in most conditions. The engines would be quite narrow so fit well within an internal slopping armour scheme. The multiple engines would give redundancy and allow for sectioning off engine areas for finer water tight divisions. In all the perfect diesel, makes you wonder why it did not happen. In Britain the fate of the Deltic was all so typical of nationalisation and inept management along with endless takeovers.
Well there is my paper monster. In 1933 it would appear as a treaty complying ship but instead be a WW2 ready 16" monster. In fact it would appear much as a slightly longer and faster South Caroline protected against most 16" guns. It would not drain limited resources too much allowing for an aircraft carrier or two plus supporting cruisers to be built by Germany for a more balanced fleet. It could outrun anything that it could not out fight until the Iowa class appeared. The Vangard would be a head ache and take on the role that the Hood did so it would not be the absolute ruler of the waves and if caught by a South Dakota would be in the usual position of likely winning but no means guaranteed. Until 1944 the only battleships that would force a fight be the Italian battleship. In fact it specifications appear similar to the Lion and USA 16" battleship classes suggest it is an achievable design. The design would enable a cookie cutter approach so should enable a class of four or more ships to be ready by 1940 with out the major design head ache that producing two two class ships that Germany did. In fact, an additional two might have been squeezed out by 1941 giving Germany a chance to take on the British Navy in a fleet action and win. The next generation would have drawn on it and been along the lines of the Iowa at a standard displacement of 50,000 tonnes. That design then could be more anti aircraft capable with automated 130mm rapid fire turrets along the lines of the USSR system but without automated shell handling the biggest shell is the 5" 38 gun as otherwise the ammunition is too heavy for fast manual handling. Maybe the Tiger automated 6" guns would give a guide that 60 RPM is possible from a triple turret 155mm system.
Have fun pulling the design to bits but for me it is near as perfect for its time and country of origin and would out gun and under weighed the Bismark. Only things is I would have named it the Seydlitz as I think a name can inspire a crew and there is not many finer names than that for a fast battleship.