My old man was a ASDIC Sonar operator on a Hunt class destroyer.
HMS Inconstant and another destroyer HMS Wilton.
one of these was responsable for a U-boat sinking. I can ask him about the range of British sonar when he was serveing.
I think secretly he wats to Hijack my PC to play SH-III and SH-IV.
back when i was a school kid my old Amiga was hijacked for Silent Service II
So tomorrow I will ask him about sonar range