Raymarine Raychart Chartplotter RC530 PLUS Determining Actual Radar Range, Radar Range Scales

Chapter 3: Standard Radar Operations 3-3

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Table 3-1: Radar Range Scales

Maximum Range	Number of Range	Range Ring Interval
(nm)	Rings	(nm)
0.125	2	0.0625
0.25	2	0.125
0.5	4	0.125
0.75	3	0.25
1.5	6	0.25
3	6	0.5
6	6	1
12	6	2
24*	6	4
48*	6	8
72*	6	12

*The maximum range depends on your scanner type, as detailed in the Pathfinder Plus Radar Scanner Owner’s Handbook.

The number of range rings shown in the table is the number to the selected range. Additional range rings are displayed to the edge of the radar picture, at the standard ring interval for the current range, and are visible when the centre is offset.

Determining Actual Radar Range

The actual maximum radar range is essentially line-of-sight, and is limited by the height of the scanner and the height of the target as shown in Figure 3-1. Table 3-2lists some range examples:

	Rmax
	a1	a2
h	Earth
		H
Radar	Rmax = 2.23 ( h + H )
		Cliff
Rmax	maximum radar range	in nautical miles
h	radar antenna height	in metres
H	target height	in metres

Rmax = radar horizon of antenna (a1) + radar horizon of target (a2)

D1643-2

Figure 3-2:	Determining Radar Range
Table 3-2:	Radar Range
Antenna Height (m) Target Height (m)		Maximum Range (nm)
3	3	7.8
3	10	10.9
5	3	8.9
5	10	12.0

Determining Actual Radar Range