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Reference
Sonar Page
Sonar Page
The Sonar Page is where your GPSMAP 178C Sounder becomes a powerful fi shfi nder. Fish are
displayed as colored arches or as fi sh icons in three different sizes. Thermoclines are shown as shades
of blue. 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. For more information on understanding sonar and the display, see page
14 and Appendix G.
Using the Adjustment Menu
The Adjustment Menu allows direct access to the settings and features most commonly used on the
Sonar Page. The currently selected option appears in the upper left of the display.
To select an adjustment option from the Sonar Page:
1. Press the ARROW KEYPAD LEFT/RIGHT to scroll through the options in the upper left of the
display, then press ENTER to access the desired option’s adjustment window.
OR:
1. Press MENU, highlight ‘Adjustments’ and press ENTER. A list of all options and their current set-
tings appears, with the selected option highlighted. Press UP/DOWN on the ARROW KEYPAD to
select the desired option and press ENTER to access the adjustment window.
To easily exit any of the adjustment options, press the QUIT key.
To change an Adjustment Menu setting:
1. Select an adjustment option to change using one of the two methods described above. The adjust-
ment window automatically times out and disappear when idle for 20 seconds.
2. Press the ARROW KEYPAD UP/DOWN to place the pointer or setting bar at the desired setting,
range or percentage (Off, 1-100%). (continued)
Sonar Page
Press MENU and highlight ‘Adjust-
ments’ to see a list of all options and
their current settings.
The Sonar Page is
The top left of the scre
fi elds allows direct acc
Page. The middle of th
beneath your boat (Ite
right side of the screen
the screen is an adjusta
the unit does not detec
appears across the Son
right side.
The sonar display
of the sonar, bottom lo
options (see pg. 34). F
(Dual 2X) on one half
The current display m
Sonar returns show
greens (weaker) and b
to view the actual sona
appear as green. When
of the fi sh symbols (an
beam (200kHz) are so
(50kHz) are hollow (o
Actual fi sh returns may
tion, and/or other cond
GPSMAP178CManual.indd 33 3/19/2004, 3:10:12 PM