Raymarine hsb2 Series, Owner'S Handbook Manual

Page: 68 / 231

Chapter 3: Standard Radar Operations 3-3
De
te
rm
in
in
g Ac
tu
al
Ra
da
r Ra
ng
e
.
* The maximum range depends on your scanner type, as detailed in the Pathfinder 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 3-2 lists some range examples:
Figure 3-2: Determining Radar Range
Table 3-1: 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
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
a
1
a
2
Earth
h
H
Cliff
Radar
D1643-2
Rmax
Rmax = 2.23 ( h + H )
Rmax
h
H
maximum radar range
radar antenna height
target height in nautical miles
in metres
in metres
Rmax = radar horizon of antenna (
a
1
) + radar horizon of target (
a
2
)