83 Khz Sensitivity (Advanced, 2D Sonar Views Only); Depth Lines (Advanced, 2D Sonar Views Only) - Humminbird 748 3D Operation Manual

83 kHz Sensitivity changes the sensitivity of the 83 kHz beam. Increasing the
83 kHz Sensitivity will display additional weak returns, and decreasing the 83
kHz Sensitivity will display fewer weak returns.
Depth Lines divide the display into four equal sections which are separated
by three horizontal depth lines. The depth of each line is displayed along the
depth scale. You can turn Depth Lines On or Off.
83 kHz Sensitivity
(Advanced, 2D Sonar Views only)
Settings: -10 to +10, Default = 0
Depth Lines
(Advanced, 2D Sonar Views only)
Settings: Off, On, Default = On
Depth Lines
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Depth Lines
Sonar Menu Tab