Need some explanation about hydrophone

[Sailor Steve]

Originally Posted by Sbygneus

1. I watched Das Boot and I saw the guy switching some switches above the hygrophone's weel. What exactly was he switching?

A quick search turned up nothing, but my guess is that they are frequency selector switches. If the sound isn't clear, limiting the frequency at which the hydrophones can hear might help. Somewhat similar to the color filters on the periscope. Or they might switch back and forth between the rotating device attached to the wheel and the static array mounted around the bow of the submarine.

2. In addition, I would like to know about the purpose of the hydrophone's weel. For example: Hydrophone is set to 180 degrees. Now lets say there is a ship above in a distance of 1000 meters at 0 degrees (exactly opposite direction) and moving fast. Would the hydrophone operator be able to hear it? Or is he totally deaf because he turned the weel in opposite direction? What was his angle to hear something in real life?

No, if the rotating device is pointed at 90 degrees he will not hear a ship at 270 degrees. For this reason he is always turning the device in different directions listening. Remember the scene where Hinrich is listening to a destroyer and suddenly turns the wheel frantically back and forth. He heard a second one and was trying to follow both of them.

On the other hand you can't hear anything at 180 degrees except your own propellors. The angle you ask about is very limited to almost a straight line. The reason is that the idea is to know exactly where the target is. The wider the angle the less precise the instrument.