you can manually override these auto values for your specific needs at any time. There are two depth settings:

shift (how far below the surface the echo sounder picture starts)

range (the depth covered by the echo sounder picture from the top of the screen to the bottom of the screen)

Setting the picture’s shift (starting depth)

The shift setting adjusts the depth of the top edge of echoes pictured on the ECHO screen. You can “shift” the entire pic- ture up and down to start at the surface of the water, or any other depth you choose.

To shift the picture:

1.At the ECHO screen, press DEPTH.

2.Press SHIFT.

Shift window

The SET SHIFT window shows a picture of the current shift settings (and range). The large white number in the black box shows the current shift value. A sliding vertical bar shows the portion of the water that the echo sounder displays on the screen, based on the shift and range set- tings.

491 Echo Sounder Operations Manual

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Image 41
NorthStar Navigation NorthStar 491 manual Setting the picture’s shift starting depth, Shift window