Slipper,
I bought Cold Waters lately and tried to find some interesting mods too. There is a realism mod which seems promising:
http://www.subsim.com/radioroom/down...o=file&id=5268
I didn't played with it yet (still doing tutorials) but I saw Jive Turkey video with this mod onboard

(full list of his great live stream videos here
https://www.youtube.com/playlist?lis...zouPXqKQD4TlZv ; Jive Turkey seems to have been in the Navy serving on submarines and talks a lot about interesting details - maybe he will give an answer whether Cold Waters are realistic or not)
Author of the mod recommends some more, which may be of interest to you:
MekStark's "Low underwater visibility" mod
his "Nato icons for campaign map" mod
and his "Hidden Sensor Comp" mod
There is also a little modification to config files to change placement of UI tabs (and I think: to get them visible all the time)
http://www.subsim.com/radioroom/showthread.php?t=233315
Good hunting
Artur