I'm more than happy I could help in any way, sonar_PL.
Maybe I couldn't tell you exactly what to change but pointing you to the files that you needed to make those changes was enough after all.
I do know that the world uses three axis coordinates with your u-boat as the center... X, Y, and Z. X is for horizontal from left to right, Y is for vertical height up and down, and Z is for horizontal from front to rear. Since visual detection is measured from the bow (front) of the u-boat, the Z-axis would be what you would modify to change how far the watch crew can see.