NorthStar EXPLORER 435 Installation And Operation Manual page 18

Shadows
Shadows are created around areas where the ultrasonic beam cannot 'see'. These areas include hollows
on the bottom or beside rocks and ledges, where the strong echoes returned off the rocks obscure the
weak echoes of the fish and may also create a double bottom trace. See following for an example of the
sonar display in such an environment. A double bottom trace is shown on the display.
Example of shadows
Northstar fishfinders display the most recent events on the right of the screen.
Moving boat
1 minute ago
18
fish is visible on the display
fish is hidden by the strong echoes off the
bottom and is not shown on the display
fish is visible on the display
Northstar Explorer 435/438 Installation and Operation Manual
Sonar display of same area
30 seconds ago
Now
When the fish symbol
option is on, any echo
returned that fits
the profile of a fish is
displayed on the screen
with a fish symbol.