GPSMAP 400/500 Series Owner’s Manual 61
Using Sonar
Whiteline—highlights the strongest signal from the bottom to
help identify its hardness or softness.
Off (default)—turns off whiteline.
High—the most sensitive setting. Almost all strong returns
are highlighted in white.
Medium—many strong returns are highlighted in white.
Low—the least sensitive setting. Only the strongest returns
are highlighted in white.
Color Scheme—select White or Blue. This affects the background
on all sonar screens, but does not change the Temp Log screen or the
Depth Log screen.
Advanced Sonar Settings
To adjust advanced sonar settings, press MENU while viewing a
sonar screen.
Pause Sonar—stops the scrolling of the sonar screen.
To mark a waypoint at a selected depth:
1. While viewing a sonar screen, press MENU > Pause Sonar.
2. Use the Rocker to position the pointer over the sh or structure
you want to mark.
3. Press SELECT.
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From the paused screen, press MENU > Resume Sonar to
continue scrolling.
Range—adjust the range of the depth scale on the right side of the
screen (Auto, or to adjust manually, Manual Range).
Gain
—controls the sensitivity of the sonar receiver (Auto, or to
adjust manually, Manual). To see more detail, increase the gain. If
the screen is cluttered, decrease the gain.
Frequency
—when using a dual frequency transducer, select how
the frequencies appear on-screen (200kHz, 50kHz, Dual, or Auto).
Zoom—zoom in to a section of the full screen. The zoom is off, or
set to No Zoom by default. Four options are available:
No Zoom—turns zooming off.
Auto 2x Zoom
—automatically tracks along the bottom at twice
the magnication.
Auto 4x Zoom
— automatically tracks along the bottom at four
times the magnication.
Manual Zoom—set the depth range of the magnied area
manually. Select Depth and then use the Rocker > Select to set
the depth range of the magnied area. Select Level and then use
the Rocker > Select to increase or decrease the magnication of
the magnied area.
Bottom Lock
—locks the zoom window to the bottom.
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