Need some explanation about hydrophone

[Sbygneus]

Hi ,
I am probably a bit dumb about technical aspects of submarines and
I have two questions about what hydrophone operator is exactly doing:

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

[saipan]

if he hears something at "0" thats dead ahead. its in relation to your bow. not sure what the dials were for in das boat.

[mookiemookie]

http://upload.wikimedia.org/wikipedia/commons/thumb/0/0b/USS_Pampanito_topside_hydrophone.JPG/220px-USS_Pampanito_topside_hydrophone.JPG

This is the hydrophone from the USS Pampanito, but it's similar to the German KDB hydrophone apparatus. The "wheel" that you see the operator turning is what turns the hydrophone head. If something were making enough noise, you'd be able to hear it even if you didn't have the hydrophone head trained at the source's exact bearing, however pointing the hydrophone at the noise's source would be ideal.

As far as the switches on the hydrophone gear, I'm not sure what each one does.

[Sailor Steve]

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.

[mookiemookie]

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.

Hmm...

This seems to imply that you could hear sounds even without the hydrophone trained directly on the source. (http://books.google.com/books?id=9kQrAAAAYAAJ&pg=PA228&lpg=PA228&dq=hydrophone+training&source=bl&ots=63nEXppNuZ&sig=e40g_lM_X-T3A8Vgm8bStKcuMG4&hl=en&ei=I-66TYKxOoSatwfjlsTJBQ&sa=X&oi=book_result&ct=result&resnum=4&ved=0CDcQ6AEwAw#v=onepage&q=hydrophone%20training&f=false)

I could be wrong. Just going off of what I read. Maybe I misunderstood it.

[Sbygneus]

Thank you all for replies. And Sailor Steve thank you for detailed information. Now I see why in SH5 you must turn the wheel almost exactly towards a sound source. It looks from the game that you hear propellers at about 6-4 degrees only. Does it mean that the hydrophone operator had to turn the wheel all the time while submerged in order to scan the surrounding area? I guess he did it from time to time?

Mookiemookie, thanks for interesting link. I am reading this google book.