How to Read a Drop Off on Sonar On July 26, 2013
This is an example on how sonar paints images that aren’t what the bottom really looks like. A person has to learn how to read a drop off on a sonar. Sonar can only paint an image with information using how far the target is from the transducer and how strong the sound returns (echo strength). This image is from a drop-off.
The white arrow is the lake bottom at the bottom of the drop-off.
The red arrow is the top of drop-off.
The black arrow is the drop-off because there is no sound to bounce off a target since sound cannot bend to see the back side of the drop-off; this is similar to using a flashlight to make a shadow. StructureScan shows strength of sound coming back as white strongest and black none. This is how you can read a drop off on a sonar.