First: OLC thanks for this wonderful mod. Even without the sun (due to my Nvidia graphics card) it's a wonderful scenery ánd GUI.
But I have some trouble with engaging my targets. Everytime my watch officer reports a merchant or warship it is too late: warships are already attacking me and merchants are already zigzagging. Even if I go immediately to periscope depth, they've already spotted me... Also speed doesn't matter and TC is not extremely high (128 or 256). In all instances visibility was moderate (9km).
I think this is due to some changes by this mod in the sensors.dat file. I don't believe the british eyes where historical better than the german's, so maybe you could do a little finetuning here in the next version and give my crew some british eyes...?