Humminbird 797c2 GPS Chartplotter Operation Manual page 21

531519-1_A - 797c2_Man_Eng.qxp 11/6/2006 5:51 AM Page 11
w for accurate interpretation of bottom contour and structure. For Side Imaging, the bottom
k and gravel provide a clearer sonar return than mud and sand because of their relative density.
ard slopes that face away from the transducer. You can find a number of easily recognizable
n of bottom contour and structure, including the following items:
The water column shows the relative
depth of the water under the boat at a
given time. Variations in the width of
the water column show variations in the
distance to the bottom as the boat
passes over.
Shadows result from a lack of reflected
sonar from a particular area, and can be
more valuable for interpretation than
the sonar reflected by the object itself.
Use shadows to help you see the image
in 3 dimensions, oriented in space. You
can gain insight into the actual shape of
an object, or the depth to which it has
sunk into the bottom, through shadows
on the display.
Temperature - water surface
temperature
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