Check this thread for the Sonar only video, should help.
http://www.subsim.com/radioroom/showthread.php?t=146795
And whilst it was trained for pre-war, it was found to be too dificult to use in practice. In SH4 though, you have very little of the problems of real problems, as the sound travels instantaneously, so there is no sonar lag. You also only get one ping off a target, so range is easy too.