Why are secondary turrets so light?

[polyarmus]

When you compare main battery and secondary battery set ups with the same number of guns and armor, the results are quite interesting (USA, 1920 starting tech).

Main battery turrets (MB) have 80 rounds per barrel and 2" turret armor and 2" top armor. Secondary battery turrets (SB) have 2" armor.

4x1x10"

MB (80; 2/2): 830 tons

SB (2): 598 tons



2x2x10"

MB (80; 2/2): 784 tons

SB (2): 568 tons



4x1x5"

MB (80; 2/2): 171 tons

SB (2): 171 tons



2x2x5"

MB (80; 2/2): 227 tons

SB (2): 159 tons

I presume, that 5" single turrets are not real turrets, but only gun shields, which would explain why main battery 2x2 is heavier than 4x1. However why is 5" secondary battery 2x2 lighter than main battery 4x1?

Another point, why is there 132 ton difference between 4x1 10" main battery and secondary battery guns (and similar difference of other combinations)? Presumably the armor is the same (2/2 and 2). Technically the turrets should be roughly similar as well. (also, if I am not mistaken, secondary batteries have more than 80 rounds per barrel).

Any thoughts?

[mycophobia]

I think this is an example of RTW armor mechanic acting a bit funny right now with regards to 4x1 5" being lighter than 2x2. However to answer why Main turret is heavier than secondry even when identical, I believe it is due to the need to extend armour belt to cover the barbette and magazine of the main turrets, which are closer to the edge of the ship(It is for the same reason why superimposed turret is heavier, since they have a taller barbette. Secondary turret are presumed to already be placed at the side of the ship and they require no extension of armour belt just for them.

[aeson]

May 30, 2019 13:25:45 GMT -6 mycophobia said:

I think this is an example of RTW armor mechanic acting a bit funny right now with regards to 4x1 5" being lighter than 2x2.

6" or lighter guns in single mounts with 2" or less turret face armor are considered to use gunshields rather than full gunhouses, which saves weight at the cost of some protection. If you use 2.5" or more turret face armor, then individually-mounted 6" and lighter guns are considered to be fully turreted and two singles will weigh more than a twin.

[polyarmus]

May 30, 2019 14:04:20 GMT -6 aeson said:

May 30, 2019 13:25:45 GMT -6 mycophobia said:

I think this is an example of RTW armor mechanic acting a bit funny right now with regards to 4x1 5" being lighter than 2x2.

6" or lighter guns in single mounts with 2" or less turret face armor are considered to use gunshields rather than full gunhouses, which saves weight at the cost of some protection. If you use 2.5" or more turret face armor, then individually-mounted 6" and lighter guns are considered to be fully turreted and two singles will weigh more than a twin.

OK. thanks