Garmin GPSMAP 178C Owner's Manual page 50

Reference
Sonar Page Options
Transducer at Surface
number to show depth
from bottom of keel
Keel Offset: Transducer
at Bottom of Keel
Enter (-) negative number to
show depth from surface
Calibrating the
40 Speed Sensor
To calibrate the water speed:
1. On the Sonar tab, use the ARROW KEYPAD to highlight ' Calibrate Water Speed' and press
ENTER.
2. Bring the boat to a cruising speed. The top ground and uncalibrated water speeds are shown at
the bottom of the calibration window. Note your top water speed, then stop the boat and press
ENTER.
Keel Offset:
3. By default, the top ground speed is automatically shown in the 'What was your top water speed?'
Enter (+) positive
fi eld. If a ground speed is not available, the top uncalibrated water speed is used instead. If the new
speed is correct, highlight 'OK' and press ENTER. If you wish to manually enter a calibration, press
ENTER on the speed fi eld, enter a new speed and press ENTER.
4. You may also press MENU from the calibration screen and choose 'Use Top Ground Speed' to
default back to ground speed or 'Use No Calibration' to use the speed sensor's uncalibrated speed.
NOTE: If the boat is not moving fast enough or the speed sensor is not outputting
a speed, you see a "Boat Is Not Moving Fast Enough To Calibrate" message at the
bottom of the display. Check that the speed sensor wheel is moving or safely increase
boat speed. If there is a problem with the speed sensor/unit or if a speed senor is not
installed, a "Water Speed Sensor Is Not Working" message appears at the bottom of
the display. Check connections of speed sensor cables.
• Set Up Page Layout — layout of the data fi elds may also be changed to show more fi elds (with a
smaller number size) or less fi elds (with a larger number size). See page 29.
• Change Numbers — allows you to specify the type of data displayed in each data fi eld. For detailed
instructions on changing the data fi elds on the Sonar Page, see pages 30-31 .
• Page Defaults — restores the Sonar Page settings to the original factory setup.
To restore default settings to the Sonar Tab:
1. Press MENU. With 'Page Defaults' highlighted, press ENTER.