Calibrating the Water Speed
If you select
Temp, Spd
for the
Transducer
option on the Setup sub
tab, you must calibrate the water speed to ensure the
Water Speed
shown on your unit is accurate. The calibration should take place in
water having little or no current.
The unit automatically uses the GPS ground speed, if it is available,
for comparison on the calibration. If a GPS ground speed is not
available, use either your boat’s speedometer reading (not always
accurate) or a stopwatch to determine your speed over a certain
distance. To find out your speed, divide the distance by the time.
To calibrate the water speed:
1. On the Setup sub tab of the Sonar tab, highlight the
Calibrate Water Speed
button, and press
ENTER
.
2. Bring the boat to a cruising speed. Both the top ground and
uncalibrated water speeds are shown at the bottom of the
calibration window. Note your top speed, then stop the boat,
and press
ENTER
.
Calibrating the Water Speed
3. By default, the top ground speed is automatically shown. 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 want to manually enter a calibration, press
ENTER
while the speed is highlighted, enter a new speed, and press
ENTER
again.
If the boat is not moving fast enough or the speed sensor is not
outputting a speed, “Boat Is Not Moving Fast Enough To Calibrate”
appears at the bottom of the screen. Check that the speed sensor
wheel is moving or safely increase boat speed. If there is a problem
with the speed sensor or if a speed sensor is not installed, “Water
Speed Sensor Is Not Working” appears at the bottom of the screen.
Check connections of speed sensor cables.
GPSMAP 378/478 Owner’s Manual
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