Raymarine Marine GPS System - Manual (Page 98)

Advanced Navigator Functions
5-7
The Standard Range Scale
Details of the standard ranges are shown in the table below. You can
also customize the range scales by specifying different ranges.
Radar Range Scales
Maximum Range (nm) Number of Range Rings Range Ring Interval (nm)
0.125
0.25
0.5
0.75
2
2
4
3
0.0625
0.125
0.125
0.25
1.5
3
6
6
0.25
0.5
6
12
24*
48*
72*
6
6
6
6
6
1
2
4
8
12
* The maximum range depends on your scanner type.
The number of range rings shown in the table is the number to the
selected range. Additional range rings are displayed toward the edge
of the radar picture, at the standard ring interval for the current range,
and are visible when the center is offset.