The shadow zone and its mysterious nature

NFunky · 10-30-09, 01:04 PM

Okay, but I'm still a bit confused here. My understanding of the shadow zone, in the most basic tactical terms, is that if the listener is above the layer, I want to be below the layer, but as close to the borderline as possible so as to remain in the shadow zone at as short a range as possible. This is very straightforward and understandable to me because of the way sound will bend away from the layer. However, my simplistic knowledge of hydroacoustics leads me to believe that for a listener under the layer there would be a shadow zone above the layer. Sound would bend away from the layer on BOTH sides yes?

As an example, lets say there are two submarines, call them 'I' and 'he' for short. Assume that I do not want to get into a shooting match, but want to remain completely undetected, that the range between the two subs is between 6 to 11 nm and that both subs are traveling at more than 7 kts (so towed arrays are hull depth). Now if he were above the layer, I would duck below it, but only the slightest bit below so as to remain in the shadow zone to the shortest possible range. My question is, if he were below the layer (lets say a few hundred feet below), would I be able to be completely undetectable if I was slightly ABOVE the layer?

I understand the concept of mutual audibility and that if he were close enough to the underside of the layer, we would be invisible to each other. However, according to your data Dr.Sid, at ranges below approx. 11 nm the shadow zone has a lower limit which can be crossed by a sub. So in my scenario above, I am placing the opposing sub below the layer, but far enough below so he is NOT in the shadow zone but can hear above-layer sounds. Would there be an area above the layer in which he could not listen (i.e. a shadow zone)? Or can he hear everything above the layer that is within sonar range?

Oh and Dr.Sid, I want to thank you very much for all the work you've put into analyzing DW's sound propagation model. I would have no clue as to how sonar performed in game without having read your threads.

10-30-09, 01:04 PM	#5
NFunky Machinist's Mate Join Date: Dec 2007 Posts: 127 Downloads: 3 Uploads: 0	Okay, but I'm still a bit confused here. My understanding of the shadow zone, in the most basic tactical terms, is that if the listener is above the layer, I want to be below the layer, but as close to the borderline as possible so as to remain in the shadow zone at as short a range as possible. This is very straightforward and understandable to me because of the way sound will bend away from the layer. However, my simplistic knowledge of hydroacoustics leads me to believe that for a listener under the layer there would be a shadow zone above the layer. Sound would bend away from the layer on BOTH sides yes? As an example, lets say there are two submarines, call them 'I' and 'he' for short. Assume that I do not want to get into a shooting match, but want to remain completely undetected, that the range between the two subs is between 6 to 11 nm and that both subs are traveling at more than 7 kts (so towed arrays are hull depth). Now if he were above the layer, I would duck below it, but only the slightest bit below so as to remain in the shadow zone to the shortest possible range. My question is, if he were below the layer (lets say a few hundred feet below), would I be able to be completely undetectable if I was slightly ABOVE the layer? I understand the concept of mutual audibility and that if he were close enough to the underside of the layer, we would be invisible to each other. However, according to your data Dr.Sid, at ranges below approx. 11 nm the shadow zone has a lower limit which can be crossed by a sub. So in my scenario above, I am placing the opposing sub below the layer, but far enough below so he is NOT in the shadow zone but can hear above-layer sounds. Would there be an area above the layer in which he could not listen (i.e. a shadow zone)? Or can he hear everything above the layer that is within sonar range? Oh and Dr.Sid, I want to thank you very much for all the work you've put into analyzing DW's sound propagation model. I would have no clue as to how sonar performed in game without having read your threads.