Why have 2 periscopes?

[Iranon]

Originally Posted by 4saken

I always use the attack periscope because of the x10...You are actually saying that with the observation periscope you can see further?

Larger optics are an advantage in the dark, and that applies here.

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Also, we need a redundant periscope if they don't do their job of slashing destroyers open (this can happen, and they sink like stones... not exactly realistic but amusing)