Wow Mittelwaechter very nice narrative and very informative. But i somehow find your method too complicated. What i usually do is once i locate a contact by hydro i allow myself a minute or so to figure out the general direction of the contact my moving the hydro angle 2-3 deg left and right of the target. Once i figure this out, i make a mental note on the amplitude of the sound and start the stopwatch. I then move the hydro angle ahead of the target by several degrees and wait for the contact to intersect it. Once it does so, i stop the stopwatch, listen for the sound amplitude and note the bearing change. This will give me a rough estimate of the contacts speed and bearing and i can move to intercept.
Cheers!
Grey
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