Got it.
And I also found a verification for the latent weakness of the torpedo defense system of US fast battleships:
The failure of Washingtons TDS between turret A and B led to the idea to improve the TDS of the Iowa by adding some extensive blisters between turret A and B (and some more forward). This could have fixed the TDS weaknes there but for some uncomfortable costs:
Most concerning is the negative effect in hull drag coefficient, reducing the top speed by between 1.2 and 1.8 kts.
But even more worrisome is that by doing this the pressure curve of the longitudinal CoB would have been shifted more aft. In the end this would have considerably decreased the seakeeping abilities of all Iowas in heavy seas by increasing the downward pull of the bow! Gurgle, gurgle.
Ahh. Some more very interesting informations provided by Nathan Okun shows that the decapping plate on Iowa and South Dakota WILL NOT DECAP a german 14.96" AP PzSprGr. 38.
Originally he simply assumed that 0.0805 calibre thicknesses of STS or comparable homogenious steel will always decap an AP projectile
(in case of Bismarcks guns: 1.205" would decap the AP. Soth Dakota has a plating of 1.25" and Iowa 1.5") Deeper investigations by Nathan Okun proved that this only belongs to soft capped AP(type 1), not hardened AP-caps.
With his corrections it would need between 0.12 and 0.14 calibre thicknesses to have a 50% chance to decap (1.8") type 2= hardened AP(compare attached image). This means the decapping plate of Iowa/South Dakota WILL ALWAYS FAIL to decap the 15" AP.
This would also effect the calculations of combinedfleet.com. The 15" AP of Bismarck will effectively penetrate Iowa and South Dakota at even longer ranges!!! It means the 15"ers will penetrate in effective conditions (EEF, formerly not possible due to decapping effect) the belt. This offsets one of the most striking advantages of South Dakota/Iowa. I have to recalculate belt penetrations