Furuno FCV-1100L - Manual (Page 62)

4. INTERPRETING THE DISPLAY
4-4
If two fish schools appear with the same color at different depths, the one in
deeper water is denser because the ultrasonic wave attenuates as it propagates
and the fish school in deep water tends to be displayed in a weaker color.
Fish Echo
Less Reddish
(Sparse echo)
Reddish
(Dense echo)
Difference in
signal strength
Weak Echo
Strong
Echo
Fish school density
4.5 Other Echoes
4.5.1 Plankton
A plankton layer, a likely place to find fish, is displayed in green or blue dots. It
usually descends in the day and rises at night.
Fish School
Plankton
Plankton
4.5.2 Current rip
A current rip develops when two ocean currents of different speeds, directions
and water temperatures meet. Its on-screen appearance is as shown below.
Current Rip
Current rip