not sure where (and even if?) to post this... but a couple of days ago I got sidetracked while googling something completely
not related...
The link said:
"Some hardly known aspects of the GHG, the U-boat's group listening apparatus.
© Arthur. O. Bauer. Diemen, 2 January 2005. The Netherlands ..."
and pointed to this file
http://www.cdvandt.org/GHG1996.pdf
A piece of some hardcore study and explanation, found it extremely interesting and thought you might think so too
Main site opens up a true treasure chest...
www.cdvandt.org