Humminbird 981 manual WHAT’S on the Side Imaging Display, Topography Changes Bottom Return Triplog

98x_Manual_531376-1_A.qxd 2/23/2005 11:40 AM 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:

Triplog

1

2

34

5	9	8
		10

6

7

11

8The 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.

9Shadows 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.

10Topography Changes

11Bottom Return

Triplog

1Depth - water depth; can be set to alarm when the water becomes too shallow.

2Timer - Elapsed time with Speed accessory or GPS Receiver.

3Distance - Distance traveled with Speed accessory or GPS Receiver.

4Average Speed - Average speed reading with Speed accessory or GPS Receiver.

5Barometric Pressure - Requires optional-purchase WeatherSense®

6Temperature - water surface temperature

7Speed - 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.

27