Chapter 3-2
CR44/54 Radar menu
3.1.1 Map 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.
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 Environmental effects
The effects of weather and water surface conditions generally act to
reduce the ability of radar to detect targets. Weather effects reduce
the long range at which targets can be detected. Water surface clut-
ter (waves) reduces the ability to detect targets close by. Either can
obscure the echoes from targets that may prove dangerous to your
vessel.
You can’t see wind on your radar screen, however you can see its
effects when it produces waves and spray on the water surface. “Sea
Return” is most pronounced in the direction from which the wind
is blowing. Proper use of your “Sea clutter” (also known as STC)
adjustment can reduce the effect of wind and waves, but care must
be taken not to increase the control to the point where weak targets
will be overlooked.
Rain, hail and snow can return echoes that appear on your radar
screen as a blurred or cluttered area. Targets within the area of
precipitation can be masked by the clutter. The maximum range of
the radar pulse is greatly reduced as the energy of the radar beam
is scattered and absorbed by the water droplets. Proper use of your
Rain Clutter (also known as FTC) adjustment helps you to look into
areas of precipitation to detect targets.
