Raymarine RayTech RNS 5.0, User Manual

Page: 61 / 152

Chapter 7: Using radar 53
7.8 How do I use radar to help avoid a collision?
You can use the following radar functions to help you avoid a collision:
• Range rings.
• VRMs/EBLs.
• MARPA.
Range rings
Range rings are concentric circles displayed on-screen and centered from your boat at
pre-set distances. The number of rings shown and their spacing changes automatically
as you change the range.
Range rings can be used as a basic method of obtaining distance information from the
radar picture.
Range rings can be turned on or off as required.
To turn range rings on/off, use the right-mouse menu, select Range Rings and click. A
check mark will appear when they are selected on.
VRMs/EBLs.
A variable range marker (VRM) and its associated electronic bearing line (EBL) is used
to determine the range and bearing (respectively) of objects detected by the radar.
A standard VRM is displayed as a circle with its center on your boat’s position, and its
EBL is displayed as a line from the origin, to the edge of the radar screen. Both are
shown as dotted lines. If you range in or out, or offset the center of the display, the
original setting of the VRM/EBL remains unchanged. RNS allows two VRMs/EBLs to be
displayed at the same time.
When a VRM/EBL pair is active, their bearing and range can be displayed in an
associated databox. This is displayed by clicking the
VRM/EBL Box
softkey to ON.
How do I use a VRM/EBL
To measure the range and/or bearing of a target or point from
your boat’s position, you need to display a VRM/EBL and edit
(move) it on- screen so that it intersects the desired target or
point.
The first VRM/EBL will be placed at a location 1/3 of the current
range and 030
0
relative to your boat’s head. If this setting is
adjusted, the display will retain the adjustments and use them
when the VRM/EBL is next turned on.
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