Garmin Fishfinder 340C Owner's Manual page 35

• Calibrate Water Speed—this appears only if you are using
a speed-capable transducer/sensor. Calibration is required
to ensure that the water speed shown on your Fishfinder is
accurate. The Fishfinder automatically uses GPS ground
speed (if available using NMEA input) 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 (distance / time = speed). It is recommended that the
calibration take place in water having little or no current.
To calibrate the water speed:
1. Use the ROCKER to highlight Calibrate Water Speed, and
press ENTER.
2. Bring the boat to a cruising speed. Both the top GPS ground
speed and uncalibrated water speed appears at the bottom
of the calibration window. Note your top speed, then stop
the boat, and press ENTER.
3. By default, the top speed automatically appears 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 speed is correct, highlight OK, and press ENTER.
If you want to manually enter a calibration, press ENTER on
the speed field, enter a new speed, and press ENTER.
Fishfinder 340C Owner's Manual
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NOTE: If the boat is not moving fast enough or the speed
sensor is not registering a speed, a "Boat Is Not Moving Fast
Enough To Calibrate" message 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 Fishfinder
speed sensor, or if a speed senor is not installed, a "Water
Speed Sensor Is Not Working" message appears at the bottom
of the screen. Check the connections of the speed sensor cables.
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