For all you 100% realism diehard captains out there . This is how to make the underwater murky so you cannot see the bow of your sub while submerged with the periscope .
If you have an envvironment mod enabled with JSGME then disable it .
Open the scene dat file (either in silent hunter 4/data , if using stock or in the mods folder )with silent editor .
click on the + next to node - sky .
click on the + next to EnvData.
click on properties.
click on the + next to underwater.
click on the + next to fog.
change the zmin = to
-30
change the zmax = to
5
