Displaying the Bottom Line
You can display lines on an echogram to mark the bottom of the trawl and the beginning of the seabed.
Procedure
Right-click the echogram, then click Draw Bottom
Line.
A yellow line appears at the bottom of the trawl and a white line
appears at the beginning of the seabed. On the example below, the first echogram
does not have a bottom line and the second has one.
![](../img/BottomLine.png)
Note: In sensors data, the opening is the distance between the
sensor and the yellow line and the height is the distance between the
sensor and the white line.