Furuno FSV-30 Operator's Manual page 112

4. ECHO SOUNDER MODE
4.7 Measuring Depth, Distance
You can measure depth and distance (picture advance set for "speed sync")
from own ship to a location with the trackball mark. Use the trackball to place the
trackball mark on the location. The trackball mark shows depth on its horizontal
axis and distance on its vertical axis.
W
How to measure depth and distance on the echo sounder display
4-12
N
1800m
S
NUMERIC/GRAPHIC
DATA DISPLAY
0
800
25
E
40
80
Distance from own
ship to mark
Depth
Trackball
mark
Range
scale