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SECTION 5
Radar Basics
The role of radar operator is to analyze the echos on the screen to assist in
proper navigation and safety of the vessel. To do the best job it is imperative to
understand the operation including advantages and weaknesses of radar. The best
way to learn is in good visibility conditions so proper comparisons can be made
between visual sightings and the representations presented on the radar display.
Some of the advantages and uses of radar are: the monitoring of other vessels in
order to avoid collisions, recognizing buoys and navigation marks for assistance in
entering and leaving port, establishing own ships position by measurement of
bearing and distance to land/islands and comparing to charts, and recognizing
heavy rain clouds. The following sections explain the screen representations.
Strength of Reflection from the Targets
The strength of a radar target depends on several conditions including
distance from you, size of the target, the height of your radar antenna, height of
the target, and the radar reflective properties of the target surface towards you.
Especially coastlines can be deceiving as a higher perpendicular surface will reflect
the radar beams back better than a beach which is sloping up and has no surface
to bounce the beams back. As shown in the illustration the closer beach may not
show as a returned echo while the mountain furthur back does show.
MOUNTAIN DISPLAYED ON THE SCREEN
SEA SHORE LINE NOT DISPLAYED ON THE SCREEN
Sea Clutters
When the sea is rough, bright noise is reflected from the wave tops especially
closer in around the center of the screen. The higher the waves, the stronger the
noises. Sometimes breakers or even ships wakes may show on the screen.
Figure 5-1
Principle
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