Calibrating The Water Speed - Garmin GPSMAP 276C Owner's Manual

S U S >
ETTING UP AND SING ONAR
Depth Number—select how efficient the digital depth update rate
is. Fast Update updates quicker and is recommended for low-noise
water deeper than 50 feet. Auto is best for shallow water or high-
noise areas, has a slower screen update, and is best used if you travel
a wide variety of depths.
If the unit is unable to track the bottom for any reason, the digits in
the depth window flash on and off to alert you that the unit is not
tracking the bottom.
Map Split Sonar Detail—select how much detail appears on the
Map Page with the sonar shown. Full Range shows data using the
Range setting of the Sonar Page, regardless of Zoom or Bottom
Lock. Maximum Detail shows any Zoom or Bottom Lock data
from the Sonar Page.
Keel Offset—enter the surface reading for the depth of a keel. This
makes it possible to measure depth from the bottom of your keel
instead of from the transducer's location. Enter a positive number
to offset for a keel. It is also possible to enter a negative number to
compensate for a large vessel that can draw several feet of water.
The Keel Offset is reflected in the depth reading.
Transducer—select the type of transducer that you are using. If you
are using a speed-capable transducer/sensor, select Temp, Spd.
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ETTING UP ONAR

Calibrating the Water Speed

If you select Temp, Spd for the Transducer option on the Setup sub
tab, you also need to 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, use the ROCKER to 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, stop the boat,
and press ENTER. By default, the top ground speed is
automatically shown. If a ground speed is not available, the
top uncalibrated water speed is used instead.
GPSMAP 276C Owner's Manual