The next thing to mod ?

Yes, that's a possibility- I think they sound a bit lightweight and tinny?

But then I've never been aboard a sub in my life, so I don't know what these hatches would sound like for "real".

On sounds, I feel that the ambient sounds when on the bridge could maybe do with a tweak; I think that maybe there should be more wind noise than there is, especially for the Atlantic? maybe more of a constant whistle and gusting of the wind together with the sea crashing against the bow of the boat. The existing ambient doesn't seem to capture the prevalence and ferocity of the Atlantic winds?
But maybe I'm wrong, what do you guys think? I've tinkered about with sounds myself, but I've no idea how to add or overlay custom sounds to the game.
There are some excellent sound packs already released I know, I use Capthelms sound mod now and it's great.