During storms, sometimes the water rises up to the zero ground of the conning tower, due to big waves. So you can set the animation of water stream down the hatch to start on that specific scenary. Then we can see the water stream coming down the hatch, coming down the stair, while standing on the command room. Sure the water stream in this case have to be much larger, it's much more water coming in. Some scenes in Das Boot show that very well, very detailed.
Racerboy, if there's someone that can do that, it's you. And sure it would be one of the best mods of all times. Hope you have the patience and the time to do that.
By the way, great work with Rubini's mod, it's now looking much better, much more realistic! Thank you very much for this!