Simrad CR34, User Manual

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Chapter 3-2 CR34/44/54 Radar menu
3.1.1 Orientation
In the RELATIVE mode, the heading line always appears on the
screen at 0° relative according to the on-screen bearing scale, and is
coincident with the antenna beam passing the ship’s bow. Thus the
top of the displayed picture represents the direction in which the ship
is heading.
All targets appearing on the display are “Relative” to own ship’s
position and heading. As you look outside at targets around you, you
will see that the targets are appearing on the Radar display at the
same relative bearing.
If the vessel alters course to the right, the displayed echoes will
be displaced by an equal amount in bearing in a counterclockwise
direction, and vice versa. These changes in the display pattern with
ship movement is an extremely important characteristic to remember
when maneuvering around nearby vessels, or buoys.
In North Up mode, the heading line will indicate the ship’s heading
in relation to the radar picture, which is presented in north up like a
chart.
The Electronic Bearing Lines (EBL) are available radar tools used
to measure bearings to radar targets from own ship. The bearing
readouts may be in relative or true modes.
3.1.2 Effects of ship’s movement
Radar images can be drawn in two ways on the radar display to
show the ship’s motion. The type of display modes are called “Rela-
tive motion” and “True motion”. In Relative motion own ship is
permanently fixed at the center of the display and radar echoes
(targets) move in relation to your vessel. With no movement of the
ship, a steady display of fixed radar echoes is shown. If the ship is
moving ahead on a constant course, echoes appearing at the top of
the display will move downward across the display. Your own ship’s
position will always remain at the center of the display.
The True motion display mode can be compared to your vessel
moving on a map or chart. In True motion mode, the surrounding
landmass echoes remain stationary on the screen and if your ship
is moving at a constant course and speed, you will see your posi-