Garmin side scan

I'm sorry for the late reply. John Crew's video is a good place to start understanding side-imaging https://bassu.tv/bass-fishing-video/electronics-graphing-a-new-lake-crews (starting at 2:55). Another excellent explanation with examples is Bryan Thrift https://bassu.tv/bass-fishing-video/electronics-master-class-bryan-thrift (explanation of side imaging is at the beginning of the video)