Escorts Insane detection (GWX)

[BigWalleye]

Originally Posted by UKönig

ASDIC detection is not dependent on sound but magnetic anomaly, or, the mass of the U-boat in water.

UKönig, could you please provide a source that explains how ASDIC actually worked. I was always under the impression that it was a form of echolocation, based on reflected sound waves (the way a bat flies at night). I had no idea that it was magnetc in nature. Could you provide any more information? Thanks.