Google Earth and Humminbird
The red line is a gpx track file I generated and loaded on the sd/mmx card (to load on my Humminbird) and also exported the file to Google Earth.
This track is in the center of the main channel of the Big Sandy River. The main channel of the Big Sandy is about 150 to 175 feet across for the most part. I will set the Humminbird to scan/record 100 feet on both sides the boat. This should show all the "loot" at the drop offs along the channel.
If you look closely at the bottom center of the map, my track and the main channel are off by about .3 miles. My stuff is right on. Don't trust Google Earth for accuracy.
This is why I got a Humminbird. Too bad file management sucks. I could be so easy to map things out if good thoughts were put into recording playbacks. But, HB is the only player one the field.
This is pretty simple stuff. I am getting old. Don't need complications.