Hi Rubini,
the game does that to all my tested (only two) subs (XXI, VII42) and
even to a normal sub in heavy weather when ever the sub shortly got washed over with water.
So your routine to regulary activate the radar is perfect for my play style.
When i get near the shores radar is off, but so the LPS
So thank you for your fast response!
And "Gute Jagd!"
Greetings
Marc