Humminbird ] 981 - Manual (Page 33)

WHAT’S ON THE SIDE IMAGING DISPLAY
Side Imaging displays a number of easily recognizable features that allow for accurate interpretation of bottom contour and structure. For Side Imaging, the bottom composition
determines the intensity of the sonar return. For example, rock and gravel provide a clearer sonar return than mud and sand because of their relative density. Upward slopes that
face the transducer reflect sonar better than downward slopes that face away from the transducer. You can find a number of easily recognizable features on the Side Imaging display
that allow for accurate interpretation of bottom contour and structure, including the following items:
Depth - water depth; can be set to alarm when the water becomes too shallow.
Temperature - water surface temperature
1
6
Speed - if a Speed accessory or GPS Receiver is attached, the 900
Series™ can display the speed of the boat, and can keep a triplog of
nautical or statute miles traveled. 7
Timer - Elapsed time with Speed accessory or GPS Receiver.
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.
2
8
Distance - Distance traveled with Speed accessory or GPS Receiver. 3
Average Speed - Average speed reading with Speed accessory or GPS Receiver. 4
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. 9
Barometric Pressure - Requires optional-purchase WeatherSense® 5
4
1
2
3
5
6
7
9
Triplog
Triplog
Topography Changes 10
Bottom Return 11
8
10
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