My monies on Sub Flags. I suggest you take that out and try again. My second choice would be Sub Exhaust.
I notice you have the mod U boat Snorkel. How does this differ from enabling the snorkel options in TDW's Option File Editor?
You need Sobers Terrain fix mod to go with OHII v2.2 full. This is no longer available in Subsim and you cannot Google it. v2.3 has the fix in it. Just copy and paste the link below and you should be fine. This mod sorts out some problems in Memel and Scapa.
http://www.4sync.com/archive/qgk_DRse/Sobers_Terrain_fix_for_OH2_V22.html