"Hearing zone"? Sorry Sir, but hearing zone of what sensor? The 180 degree arc in front I believe is ASDIC (active sonar), and the 270 degree arc, farther out, I believe is the hydrophones with it's missing area in the ship's baffles. Is there a sensor which is indicated by the full circle who's range is in between the above mentioned two? As I said..."I believe"...please correct me if I'm wrong on these.
As always...
