Draken wrote:What about copying backup system from battleships, turrets were manual if I'm correct and even diesel engine should be precise enough for turning it.
I don't know enough about early, Dreadnaught era, battleships, but I'm pretty sure that turrets for big guns have always been powered by electric or hydraulic motors. I'm sure that Charis has already reached the point where manual, human powered, turret control is not really feasible, and they have considerable experience with hydraulic and pneumatic systems powered by PTOs from the main engines.
The problem isn't really turning the turrets/barbettes but in stabilizing the guns (and/or ship) relative to the horizon so they can be aimed with some accuracy. The best way to manage that is with a gyroscope -- either a massive one to keep the guns/ship stable or several smaller gyros controlling hydraulic actuators to move the guns counter to the ship's movement.
There's nothing in that particular problem amenable to solving with an IC engine; except for driving a hydraulic pump and that can be done by the main steam engine or a steam auxiliary engine without needing to mix technologies and/or carry a separate fuel supply for the turrets.
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Answers! I got lots of answers!
(Now if I could just find the right questions.)