@knp7765:
I was also wondering if Battle Cruisers and Pocket Battleships should be considered the same class or different. I think Battle Cruisers were heavier armored and armed than Pocket Battleships, which were sometimes considered very heavy cruisers. Also, should Battle Cruisers also take 2 hits to sink? Any other differences between early war BBs, late war BBs and Heavy BBs? Any ideas would be welcome.
I’m not experienced at converting historical ship data into game combat values, so I’ll just provide some background information on the ship types you’ve asked about.
The Deutschland-class Panzerschiffe (which the British press nicknamed pocket battleships) were an odd hybrid of several ship types. They had 11-inch guns like a first-generation German dreadnought battleship or battlecruiser, carried fewer of those guns than a typical battlecruiser (and much fewer than a battleship), were about the size of a heavy cruiser, were only moderately fast by cruiser standards (though they did have a very long range), and had weak armour protection roughly on the scale of a light cruiser. They can most concisely be described as over-gunned and under-armoured heavy cruisers.
Battlecruisers were notoriously easier to sink compared with battleships, as demonstrated by the Battle of Jutland in WWI and the destruction of the Hood in WWII. This is hardly surprising because battlecruisers traded protection for speed: they had less armour (and fewer guns) than battleships, but were faster. For a battleship, the rule of thumb for a balanced design was that the armour protection had to be proportional to its own firepower, meaning adequate enough to allow the vessel to fight against another battleship carrying guns of the same caliber as its own. Battlecruisers, by contrast, were unbalanced designs – in the most extreme cases, they were eggshells armed with hammers. (One oddity was the Scharnhorst class, which reversed the usual battlecruiser philosophy: they were over-armoured relative to their original 11-inch guns because they were intended to be uprated to 15-inch guns at a later date.)
One final note about battlecruisers concerns the odd situation of the United States. On the one hand, the US demonstrated that the battlecruiser concept was pointless when it built the Iowa class. The Iowas showed that, with WWII-era technology and a good design, you could combine the firepower and the armour protection of a battleship with the speed of a battlecruiser (and indeed superior to that of most battlecruisers). On the other hand, the US – which had never previously completed any battlecruisers – became the last nation ever to build them when it produced the Alaska class 12-inch gun super-heavy cruisers. They were fine ships but a poor investment: no faster than the Iowas (33 knots), but much weaker in firepower and armour. The US would have been better off completing Illinois and Kentucky, the planned third pair of Iowas.
In terms of early and late battleships, the dividing line would roughly be between battleships built prior to about 1930 and those built afterwards. The pre-1930 ships were mostly of WWI vintage, with a few additions in the 1920s. They’re usually described as “slow battleships,” reflecting the fact that, at that time, you generally had to choose between power (battleships) and speed (battlecruisers) in your designs. The battleships from the 1930s and 1940s are known as “fast battleships” because they were much faster than WWI-vintage battleships; fast battleships could make at least 27 knots, and several classes (notably the Iowas and the Littorios) could do even better than that. So that’s one way to divide battleships. Another way of dividing them would be into a European group and a Pacific group. This has nothing to do with A&A Europe and A&A Pacific (though it’s a nice coincidence), but rather reflects the fact that the most modern battleships used by Britain, France, Germany and Italy during WWII tended to be smaller in size and armament (typically 14-inch and 15-inch guns) than the ones used by the US and Japan, which were bigger in size and armament (mostly 16-inch guns, with some 14-inch ones). The 18-inch Yamatos, however, were glaring statistical outliers, so they deserve their own category. The same case could be made for the Iowas, which hold the speed record for battleships and whose 16-inch main guns (50-caliber-length weapons firing very heavyweight shells) delivered an armour-piercing punch which was not all that much smaller than that of the Yamatos, which were shorter (thus producing less muzzle velocity) and which fired AP shells which had a smaller weight-to-size ratio.