Hi h.sie,
How are you mate?
Sorry to be totally OT from your current work (radar lenght). I have not any knowledge to help you on this matter.
But I should like to suggest a new item on your to do list about hydrophones.
I guess that you know that some months ago I tried/made a small mod that adds three layers for hydrophone to add more playability and realism for the hydrophones . Also i guess that you have noted that only the more deep layer allows the player to listen by himself on the hidro station. A limitation from Sh3 that makes that mod just useful for half of the users.
Perhaps with hardfix could be not difficult to cut the max hydrophone range (on sensors.dat) accordingly the depth of the uboat. Let's say: PD to -18m: 12000m, -17 to -28m: 18000m and <-28m: the maxrange as it is on sensors.dat.
Thanks again by your great work. The radar fix will be another great addition!