[the dark knight]

Sondergerat Fur Aktive Schallortung (or S-Gerat)

(Special Apparatus for Active Sound Location) was essentially sonar. It transmitted sound pulses and timed the returning echo. Because it emitted sound pulses which also broadcasted the U-boat’s location, this device was not very popular. It could detect objects up to 4,000 meters away. However this system was a bit temperamental and it's ability to detect the range to a target depended on so many things, salinity, sea state and even temperature (plus easily damaged by depth charges). I have read instances where the S-Gerat for what ever reason, did not detect a target at 2,000m or less. Because of it's unpopularity and uselessness, most if not all the U-boats fitted with S-Gerat had them removed later on in life.

I do not bother to mount it since the real one did not work properly, nor was it very effective.