The Recording feature of your unit is a very good learning tool...

When I first got my unit I would fish until about an hour before dark...
Then I would motor to a point about 1/2 mile from my launch ramp...
Then I would start a recording and record the entire stretch of bank all the way to the ramp...(without fishing)...
Then I would take that recording home and study it to learn SI image interpretation..
Playing the recording back even has the benenfit of marking waypoints on interesting structure shown on the recording...
I still have some of those first recordings I ever made...
I have an entire SD card dedicated just for saved recordings that I can study any time I want..
There is a "learning curve" to ascertain what different structure looks like...
Studying the recording at home is invaluable..(there are no distractions during study time this way)...
Rickie