SH5 Deck gun.
 

When the boat is surfaced, I presume that if the sea is a bit too rough and the deck is getting flooded, that the deck crew won't man the deck gun?
Is this assumption correct?

I know in vanilla SH5 they wouldn't man the deck gun if the deck was underwater. In some cases in rough seas (if the deck wasn't constantly awash but occasionally underwater) the deck gun would be 'manned', but the gun would only fire if the deck was above water. Alternatively, so long as you were 'surfaced', you could run down and man the gun yourself and fire regardless of whether you were 10 ft underwater or 10ft above it

Hello Harmer

Yessir pretty much so, can apply when sea appears relatively calm (visually) . Can be mounted manually but gun will not pivot so you can only track and aim by steering the boat unless it calm obviously