I use a 997c SI with a towfish to locate structure and to troll over previously marked locations.
Side Imaging Soft post links ...
Towfish ... (http://forums.sideimagingsoft.com/index.php?topic=458.0)
(http://photos.imageevent.com/limbatus/2010/misc1/SIS-topic-458.0.jpg) (http://forums.sideimagingsoft.com/index.php?topic=458.0)
Short tether ... (http://forums.sideimagingsoft.com/index.php?topic=1000.0)
(http://photos.imageevent.com/limbatus/2010/misc1/SIS-topic-1000.0.jpg) (http://forums.sideimagingsoft.com/index.php?topic=1000.0)