Great thread idea!

Im wondering about the effectiveness of ww2 passive sonar vs the speed of the destroyer using it. Currently Im replaying a situation I saved that placed me almost dead ahead of a TF containing 8 AS ships, 3 to a side, one ea front and back, the QE and the Hood

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Im inside the screens line of travel waiting for my juicy targets and Im at 1 kt and they are traveling at 19 kts. At this point Im tracking by sonar, yet they still detect me somehow and go active. Im just having a really hard time believing British sonar in late 39 is this good. Any idea whats going on here?