Hi .. the shadow zone is bellow the layer, and it starts at some distance and it lies further on. It's not symetric in it's shape. The top edge is horizontal, the side edge is parabolic (visible on those graphs I did in that other thread). It has no limit on 'the right side' and towards the bottom.
However .. in sonar there is a rule (forget the name now), if A hears B, B hears A. And it is correctly implemented in DW as much as I tested.I only did it one way, because it was easier.
So my measurements had target on the surface, and listener (array) at variable depth. But the transition loss should be the same the other way around.
So if you are in the shadow zone (considering some other listener), you can't hear him, he can't hear you. In DW, shadow zone is absolute and the transition is abrupt. So you can ping, cavitate, whatever .. the other guy won't hear a single dB of noise.
DW's model is quite simple (IIRC)
Both above the layer - good signal
One above, one bellow, in the shadow zone (far enough) - no signal at all
One above, one bellow, not it shadow zone (close enough) - somewhat weaker signal
Only one case is left. Both under the layer. I'm not sure if it is mentioned in that old thread, but it behaved same as the last mentioned case - ie weaker signal, shadow zone had no effect.
And of course it opens space for tactics, that's what the layer is good for. Good idea is especially to launch torpedoes on the other side of the layer, then steer them around, so when they finally get detected (usually by getting closer then 3nm shadow zone edge), they will come from different direction then you are.
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