I'm gonna say this is a must have - realism wise.
Combine it with a torpedo room mod, and it'd be totally epic - so long as it didn't hog frames.
Oh, the ability to control the ballast tanks separately to allow counter flooding if say flooding was stopped but pumps destroyed would be awesome too. For the record, my stern torpedo room had completely flooded due to a shell hit, but I was still sufficiently buoyant to continue the mission. The only thing that stopped me was the fact that my stern would sink, and my bow would shoot out of the water - forcing me to sprint to the nearest port on the surface.
And the ability to open and close compartment doors without going through them would be pretty sweet, too.
Sorry for the off-topic-ness
All those ideas popped into my head at once,
