Understanding The Down Imaging® Display; Interpreting The Display - Humminbird 698ci HD SI Combo Operation Manual

Interpreting the Display

Down Imaging® beams "illuminate" the bottom contour, structure, and fish.
The beams are wide (side to side) but very thin front to back.
Use the light and dark parts of the display to interpret the objects under your
boat as follows:
• Dark shades represent soft returns (mud, sand) or descending terrain.
• Light shades represent denser terrain (timber, rocks) or rising terrain. A
very hard bottom may appear as white on the display.
• White Streaks or Clouds may represent fish on the display.
• Shadows are not caused by light but by the lack of a sonar return.
Objects standing on the bottom cause a sonar shadow to appear on the
display. The longer the shadow, the taller the object. Fish may also cast
shadows. You can use the shadow to interpret where the fish or object
is located in relation to the bottom.
What's on the Down Imaging® Display
Understanding the
Down Imaging® Display
The images you see on the Down Imaging® display
are produced using sonar technology. Each time the
unit pings, a strip of data representing all the
echoes received by the transducer are put together
on the display to form the image that you see. Like
traditional 2D Sonar, the sonar history scrolls left
across the screen.
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