Hi,
and some notes to this nice thread!
On a side note, PI decided to leave out the O-class BCs and instead made the P-class CA's be the BC model after the Scharnhorst. Not sure why they did that. To compare, the P-class was to have 6 11" guns and 120mm belt armor, while the Scharnhorst had 9 11" guns and 350mm belt armor, and the O-class battlecruisers were to have 6 15" guns and 190mm belt armor. In terms of armor and firepower, the P-class shouldn't be a battlecruiser. The only reason I can think of to justify classing the P-class as BCs is their sheer size. The previous CA class, the Admiral Hipper, was 202m long, while the P's were to be 230m long. In comparison, the Scharnhorst and O's were 235m and 256m long, respectively, making the P-class be about the same physical size as the Scharnhorst, despite having much poorer "specs".
The P-class was the planned successor for the Deutschland-Class Superheavy(in terms of guns) CA.
Initially they should get the 6*28cm but it was also planned to fit the 38cm double turrets into them.
P-class should get some better protection but much more speed, initial designes varied:
displacement: 20000-21000 tons
side armour : 120mm
speed: 34-35knots
range: 15k nautical miles
armament: 6*28cm in doube or triple turrets..
Planning started '37 and in '39 over 20 different construction plans were made and varied again from 21k tons up to 31k tons from length of 206-235m..
Constrcution problems:
For the usage of 2 triple turrets you need at least a lengt of 218m. but would have to drop the underwater protection because you would else scarifice the speed("Schlankheitsgrad des Schiffes" would be to bad.) as the width for that speed shouldn't exceed 25m..
So to get the needed amount of engine power for that speed would need a width alone of 19m(length 92m), plus underwaterprotection of 4m sums up in the end to ~27width and leads to a length of 237m..
But a ship of that size would have also exceeded the naval treaty with the amount of needed displacement..
All that problems led to the planings(!) that 3 of the 12 planned P-class ships, 3 should be the O-class with the 2*3 38cm guns.
Notabel design speciality was that these ships should get transom sterns.
Scharnhorst was the planned answer for the french Dunkerque-Class and started with a planned tonnage of 19000 in '34 with just 2x3*28cm! A third turret was only planned..
The plans were based on ideas from 1928.
Construction plans from 1928 for new german BC:
length: 206
width: 25
depth: 7,8
engine: 160k horsepower
speed: 34knots
Armor:
side 100mm(note! less than for the later p-class..)
deck 25mm
armor deck 30/20mm
aft/bow 80mm
turrets 250mm
Armament: 8*30,5cm(SK L/55 in 4x2)
9*15cm
4*8,8cm
Construction weight/displacement: 19192 ts..
But noone was happy with that plans back then and also not for the new Scharnhorst-class and the weight raised up to 26k tons to have more armor and more guns(9*28cm).
Now the old plans of Mackensen Class and Ersatz York Class were taken into consideration and the weight raised again for 6k tons..
That raised protection lvl now brought up a discussion about the main armament from 9*28cm and to raise it to 9*35cm or 9*38cm.
But some artillery officers favoured the 28cm guns for their higher rate of fire.
In the end Hiter decided to only use the 9*28cm beacuse of the estimated reaction of the UK if they had choosen a higher calibre.
All in '34..
In '35 it was then examinated if the class could use also the bigger 2*38cm turrets with slight modifactions. That was possible but not planned initially.
Also notabel for the weight of a ship. Most ships used still bolted armor.
But the Scharhorst Class also used new alloys called "Wotan hart" and Wotan weich"(Hart=hard, weich=soft) wich could be used with a new welding technique and had a much better protection with the same thickness of its armor!
In the end the Scharhorst-Class construction weight raised to 34841 tons! ~15k tons more as initially planned..
Bismarck and Tirpitz wer planned in '35 and had an intiall construction weight of 35k each.
Changes in the building phase made a raise of 10k tons neccessary, wich were still in the limits of the GER-UK treaty..
38cm were choosen, because this guns seem to be quite sufficient and could be also used later in other designs.
(Funds savings in mind, no need to build bigger guns then needed..)
In the end combat displacement was in the 50k+ tons.
H-Class is a diferent topic.
I'll add some more info maybe.
For now I just want to add that thise class also had still most a max calibre of 40,6cm initially in mind but also a displacement up to 80ktons.. The later designs with bigger calibres are a another different story..
I still think that a SHBB is right in the game, as the Yamato was planned in '34 and after ~23 different construction plans and ~50 model trials the final construction plan was done in '37.
Construction displacement was 68000 tons in '37. That is nearly double as much as other designs of that time!
And even the later planned Montana-calls had a planned construction displacement of "only" 58000 tons(with 12*40,6cm in 4 tripple turrets). And that already 6 years later.
Also the Montana-Class wouldn't fit anymore through the Panama-Canal wich was one goal of the Japanese. That the uS would have to build so big ships that wouldn't fit through that canal.
The big main armament of 46cm guns was also unmatched of that time and the protection of vital parts planned with 40,6cm munition in mind.
In the game it would be "hard" to simulate the design apprach of the Yamato or later H-Class designs with only one BB type unit.
As we see, navies would tend to still build maybe not so big ships at the same time.
You would need to have already researched up to 46cm guns in '37 to be able to build such a ship. And the engine would then only build such SHBB etc..
Cheers,
Chromos