Furuno 821 Operator's Manual page 13

A
B
Own ship
(radar)
(A) Bird's eye view of situation
2
Targets
D
C
Figure 1-1 How radar works
Heading marker
A
B
C
Own ship
in center
(B) Radar picture of (A)
Range and bearing
of a target, relative
to own ship, are
D readable on the PPI.