Garmin GPSMAP 178 Owner's Manual page 50

Reference
Sonar Tab Options
Transducer at Surface
number to show depth
Keel Offset: Transducer
Enter (-) negative number to
show depth from surface
Calibrating the
Speed Sensor
0
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.
3. By default, the top ground speed is automatically shown in the 'What was your top water speed?'
field. If a ground speed is not available, the top uncalibrated water speed is used instead. If the new
Keel Offset:
speed is correct, highlight 'OK' and press ENTER. If you wish to manually enter a calibration, press
ENTER on the speed field, enter a new speed and press ENTER.
Enter (+) positive
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.
from bottom of keel
I
NOTE: If the boat s not movng fast enough or the speed sensor s not outputtng a
speed, you see a "Boat Is Not Movng Fast Enough To Calbrate" message at the bottom
of the dsplay. Check that the speed sensor wheel s movng or safely ncrease boat
speed. If there s a problem wth the speed sensor/unt or f a speed senor s not nstalled,
a "Water Speed Sensor Is Not Workng" message appears at the bottom of the dsplay.
at Bottom of Keel
Check connectons of speed sensor cables.
• Set Up Page Layout — layout of the data fields may also be changed to show more fields (with a
smaller number size) or less fields (with a larger number size). See page 29.
• Change Numbers — allows you to specify the type of data displayed in each data field. For detailed
instructions on changing the data fields 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.