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14
Getting Started
Map/Sonar Split &
Sonar Pages
Map/Sonar Split Page
The Map/Sonar Split Page combines the Map Page on the left half with the Sonar Page on the right
by default. You may adjust the size of the split (pg 32). Press PAGE key to proceed to the Sonar Page.
Sonar Page
The Sonar Page is where your GPSMAP 178C Sounder becomes a powerful fi shfi nder. The top left
of the screen contains data fi elds, while the Adjustment Bar above the data fi elds allows direct access
to the settings most commonly changed while using the Sonar Page. The middle of the page contains a
right-to-left moving sonar image of the water beneath your boat (Items appear as they pass under your
transducer. Those items on the right side of the screen are closer to you than those on the left.). Along
the right side of the screen is an adjustable scale which refl ects the depth of the area being displayed. If
the unit does not detect a transducer attached to the unit, a “Sonar Turned Off” message appears across
the Sonar Page. You may also show a sonar fl asher and color bar on the right side.
The sonar display may also be set to show a split screen view of a zoomed portion of the sonar,
bottom lock (display scaled from the bottom up), or a combination of these options (see pg. 34). For
example, you may choose to show dual frequency at a 2X zoom (Dual 2X) on one half and normal
range dual frequency (Dual) returns on the other half. The current display mode is displayed at the
bottom of each sonar display.
Sonar returns show as red (strongest), then oranges (strong), yellows (medium), greens (weaker)
and blues (weakest). The ‘Fish Symbols’ option (see page 38) allows you to view the actual sonar data,
a fi sh symbol, or a combination of both. ‘Fish Symbols’ appear as green. When the unit is set to ‘ Dual’
frequency (see page 35), the appearance of the fi sh symbols (and simulated fi sh returns) changes. Fish
symbols from the narrower beam (200kHz) are solid (or narrow returns), but the symbols from the
wider beam (50kHz) are hollow (or wide returns). Fish icons are displayed in three different sizes.
Actual fi sh returns may not always appear as perfect arches, due to the speed, fi sh orientation, and/or
other conditions.
More on understanding the Sonar Page may be found on pages 33 and in Appendix G.
Dual frequency returns
Sonar Page
Data Fields
Depth
Scale
Adjustment
Menu
Simulated
Fish Arch
Bottom
Thermocline
Center beam
return
Outer edge
beam returns
Frequency
mode
Flasher
GPSMAP178CManual.indd 14 3/19/2004, 3:10:00 PM