brendan,
Here's some other hydrophone hunting tutorials you might find interesting.
http://forums.ubi.com/eve/forums/a/t...7821098535/p/1
and
http://www.subsim.com/radioroom/showthread.php?t=110619
The video (U42HydroHunt.exe) for both posts has also been uploaded to my Filefront. See link under my sig
cheers