I don't know if you side-imaging guys have this or not. It's a real nice program.

The HumViewer is a program that can be used to view sonar recordings created on a Humminbird sonar (Side-imaging or Quadrabeam).
The current version is 67 This Link is where I got this info. To download the program it is free. I had no problems running it. HumViewer - Viewer of Humminbird sonar recording files

Features
The main features of the program is:
View both Side imaging and 2D (down) sonar recordings
Shows the track where the recording was done.
Change contrast/brightness to enhance image.
Create waypoints and user tracks from the recordings
Export recording track, user tracks and waypoints to .kml, .gpx and .csv files
Create movie of recording
Create snapshot .jpeg, .png or .bmp file
Create sub-recording (save part of recording) as new recording
Measure lenght/distance and estimate height of objects seen in recordings
and some more...