what year?
rigged for silent running?
if you were not rigged for silent running there are any number of fans, motors and such all humming along... which could be overheard by a skilled hydrophone listener.
I had a hunter killer do that same routine to me in 1944.
I was about 3KM away resting on the bottom rigged for silent running at over 180 meters deep and they made a bee-line right for me and squashed me like a bug.
i dont know how that happens
