Raymarine E90W, Руководство пользователя, Страница: 141 / 250

3. Select Radar Alarms Setup .
4. Select Guard Zones Sensitivity .
5. Use the rotary control or trackpad to adjust the sensitivity.
MARPA overview
MARPA is used for target tracking and risk analysis in the radar
application.
With an accurate heading sensor connected to your multifunction
display, you can use the Mini Automatic Radar Plotting Aid (MARPA)
functions for target tracking and risk analysis. MARPA improves
collision avoidance by calculating information for tracked targets,
and provides continuous, accurate, and rapid situation evaluation.
The number of targets that you can track at any one time is
dependent on the model of radar scanner that you are using.
MARPA tracks acquired targets, and calculates the target’s speed
and course.
Each target tracked can be displayed with a graphic indicating the
Closest Point of Approach (CPA), and Time to Closest Point of
Approach (TCPA). The calculated target data can also be shown on
your screen. Each target is continually assessed and an audible
alarm is sounded if a target becomes dangerous, or is lost.
For effective MARPA operation, your multifunction display must
have accurate heading and speed data for your vessel. The better
the quality of the heading and speed data, the better MARPA will
perform. For the best heading data, a Raymarine SMART heading
sensor or a gyro-stabilized autopilot is required.
In True Motion mode, Speed Over Ground (SOG) and Course Over
Ground (COG) information is required to show true target course
and speed.
In Relative Motion mode, heading and speed information is required.
Safety notices
MARPA can improve collision avoidance when used wisely. It is
your responsibility to exercise common prudence and navigational
judgement.
There are conditions where acquiring a target may become difficult.
These same conditions may be a factor in successfully tracking a
target. Some of the conditions are:
• The target echo is weak. The target is very close to land, buoys
or other large targets.
• The target or your own vessel is making rapid manoeuvres.
• Choppy sea state conditions exist and the target is buried in
excessive sea clutter or in deep swells.
• Choppy sea state conditions exist yielding poor stability; own
vessel’s heading data is very unstable.
• Inadequate heading data.
Symptoms of such conditions include:
• target acquisition is difficult and the MARPA vectors are unstable;
Using radar
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