Atma wrote:
The range finders on top of the number 2# turret, dont penetrate the roof, all you see above the roof is the whole range finder, the whole "device". If its a true a "sighting hood" it can be used for training reasons. It can be for various calibration methods or something similar, dont have to be a range finder device.
This type of range finder was used for example on board a USS Tennessee class battleship, no such a an access hatch was required for the same type of range finders used on older battleships.And in any case it can be a access point but im 100% is unrelated the range finders on top of the turret roof.
Penetrating a turret roof is was not a preferable idea for any navy that was building heavy gun turrets that needed immense protection and tons of iron.It looses its integrity, it was general avoided.
I'm aware that the Rangefinder doesn't penetrate the roof, I said that earlier, but they would have direct access to it, to allow the crew to abandon the position once range dropped. It's certainly not a 'sighting hood' or the rangefinder wouldn't be mounted in-front of it. the turret roofs were actually quite thin (as shown on the Tennessee -
http://www.researcheratlarge.com/Ships/BB43/PearlHarborDamageReport.html Photos 3-6 - note: the bomb (actually a 14" AP shell with fins added) did not detonate. It fell about 10,000' at about 75deg, hit the Yard arm of the main mast, then slammed into the turret roof and catapult, and still did this kind of damage - not that much armor) WWI British Battleships had "sighting hoods" on most of their turrets (I've heard unsubstantiated reports that these prevented superimposed turrets from actually firing over the top of lower turrets but am not convinced.)
Anyway, there is one other possibility, Battleships at this time did not always practice with their main guns. to reduce wear and tear on gun tubes, they would be fitted with small (3" or so) practice guns on the turret roofs (unable to locate picks now but they're there.) which would be fired instead of the actual main guns during practice. this could be one of those mountings - the gun having been removed but the mounting remaining for future use - that never came.