CA4
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8.1.1 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 coinci-
dent 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 posi-
tion 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
maybeinrelativeortruemodes.
8.1.2 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 clutter
(waves) reduces the ability to detect targets close by. Either can ob-
scure the echoes from targets that may prove dangerous to your vessel.
You can’tseewind 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) adjust-
ment 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.
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