As far as I have noticed, there’s a quite pronounced survivability difference between the early battleships when it comes to defending against destroyer- and cruiser-level armaments, something that is very commonly fought in the current botscape.
Essentially every dreadnought in game is impervious to most cruiser armaments (notable exceptions: Graf Spee & Hipper) when it comes to citadel armour, but their survivability against HE shellfire varies greatly:
Take the Westfalen for example:
The german starter dreadnought is pretty well set up with only 12 guns (+ 2 MG08s) out in the open, with another 16 (4x88mm + 12x150mm) guns enclosed. 8 of the “open” guns are under deck too, so hitting those requires direct fire.
These are as far as I know the only areas you can damage the Westfalen’s crew without being able to penetrate it. To compensate for this, the Westfalens armament is somewhat on the smaller end, with only 11in bore, yielding a little less penetration power and damage output, while running a somewhat faster reload.
The Paris, being France’s contribution to the early dreadnought experience, is greatly survivable against HE barrages:
The Paris only has 7 guns (+2 + 4x2 Hochkiss machine guns) open on the deck, minimising the area filled by damage susceptible components. Its main armament does have even less penetration than the Westfalen, even though it runs 12in guns, owing to its much lower velocity.
However, there is ONE 6.0 dreadnought that envies this protection pretty badly:
The grandfather itself, HMS Dreadnought (00):
The Dreadnought has not 8, not 12, not 15, but 20 guns out in the open.
This means that the Dreadnought itself, even though it is able to stand its ground against other battleships, gets melted by any sort of HE slinging destroyer or cruiser (looking at you US navy), as once you want to repair (for example you lose a gun, which means a whole turret, as theyre twin guns), you are also forced to repair ALL your secondaries (-> putting crew in harm’s way), yielding a battleship much worse at fighting supposedly “lesser” vessels than itself.
A rather amusing side effect of this is that while the two others fare much worse in an uptier, the Dreadnought has the potential to be more survivable in a 6.0-7.0 match… (granted efficient use of angling and firing angle exploitation)
Thus, one may consider the Westfalen and the Dreadnought to have opposite roles: One is to clean up the lesser, while the other is to go toe to toe with its equals.
(Just to mention: the Paris has the worst citadel out of the three, thus is the most susceptible to ACTUALLY getting penetrated, somewhat neutralising the HE survivability)