DownScan VS 2D Sonar On February 02, 2014
Interpreting Sonar Displays
Regular sonar (2D sonar) sometimes can’t define the details as well as DownScan sonar.
DownScan has a very narrow beam front to back and wide beam side to side so you will “see” finer details.
Bait fish are going to show up as fine grain dots, like under the green arrows, while the larger fish are larger white returns like above the black arrows. The regular, or 2D sonar, tends to blend the returns together because of the wider shape of the beam in all directions.
While the DownScan shows better detail, it is dependent on a steady forward motion for the beam to cover the bottom of the lake or river, much like the light bar on a photocopy machine.