This attribute is controlled for each submarine in the folder:
.../data/submarine/NSSuboatXYZ/NSSuboatXYZ.cfg
Open the .cfg of each sub with Notepad and look for "sormconditions". It has two values; the fist is wind [0 to 15] and the second is rain intensity [0 to 1]. Change the two values as you deem appropriate.
I already made a small fix for the XXI sub, which corrects this glitch (since the XXI has closed flak turrets).
http://www.subsim.com/phpBB/viewtopic.php?t=47637
Check it out and you can make your own fixes.
Hope this helps
VonHelsching