hydrophone superman?

Catfish · 03-09-10, 08:01 AM

Hello,
technically there were two hydrophone devices for detecting noise underwater, one set was the "GHG" or Gruppenhorchgeraet, located around the fore dive planes, left and right. You can see those microphone arrays clearly in exterior view.

Since this GHG is located underwater even if the boat is surfaced, it is well possible to get hydrophone contacts surfaced, if only at very slow speeds and few wave action.
But: When the Diesel engines are running it will be almost impossible to hear something not only due to the engines, but spray and bowwave turbulences around the dive planes due to the speed of the boat.
As well the hydrophones are not far below the surface, so as it is stated in the manuals of the time, a depth of 30+ meters will be best for listening, unless there is big wave action with a wave base (wavelength/2) of more than those 30 meters.
WHich is b.t.w. the reason why destroyers would seldomly detect U-boats at periscope depth with hydrophones, or active sonar ("ASDIC")

The second hydrophone device called the "Kristallbasisdrehgeraet" was located on top of the fore deck, so no listening with that one surfaced. It was more sensible than the GHG and already used piezotechnology, for picking up faintest noise.

Unfortunately there is only one hydrophone device type modelled in the interior of the boat ...

Greetings,
Catfish

03-09-10, 08:01 AM	#6
Catfish Dipped Squirrel Operative Join Date: Sep 2001 Location: ..where the ocean meets the sky Posts: 17,811 Downloads: 38 Uploads: 0	Hello, technically there were two hydrophone devices for detecting noise underwater, one set was the "GHG" or Gruppenhorchgeraet, located around the fore dive planes, left and right. You can see those microphone arrays clearly in exterior view. Since this GHG is located underwater even if the boat is surfaced, it is well possible to get hydrophone contacts surfaced, if only at very slow speeds and few wave action. But: When the Diesel engines are running it will be almost impossible to hear something not only due to the engines, but spray and bowwave turbulences around the dive planes due to the speed of the boat. As well the hydrophones are not far below the surface, so as it is stated in the manuals of the time, a depth of 30+ meters will be best for listening, unless there is big wave action with a wave base (wavelength/2) of more than those 30 meters. WHich is b.t.w. the reason why destroyers would seldomly detect U-boats at periscope depth with hydrophones, or active sonar ("ASDIC") The second hydrophone device called the "Kristallbasisdrehgeraet" was located on top of the fore deck, so no listening with that one surfaced. It was more sensible than the GHG and already used piezotechnology, for picking up faintest noise. Unfortunately there is only one hydrophone device type modelled in the interior of the boat ... Greetings, Catfish