12 Radar Systems of Maritime Transport
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• possibility of navigation control without distraction from observing the surroundings and without prejudice to other tasks;
• simplicity, visual aspects, reliability of the applied methods, excluding mistakes.
The navigator who manages the vessel (the captain of the vessel or his substitute
senior mate) mainly uses accelerated (pilotage) methods to control the position
and movement of the vessel (leading, control, fencing bearings and distances),
including using radar and ARPS.
The deck officer (officer of the watch, OOW) performs navigational plotting and
periodically determines the ship’s position using normal pilot methods in order to:
• duplication of control in position and movement of the vessel and the timely
detection of possible misses and errors;
• performing the necessary calculations, and obtaining objective data on the ship’s
deviation from the line of a given track, on the course angle, drift angle and ground
speed, on the direction and speed of the total drift, on the distance and bearing to
the point of the beginning of the turn, time to turn, etc.;
• timely providing of the navigator, managing the vessel, with all necessary
navigational information.
When using radar and ARPS, the most effective and efficient method is visual
control of the position and movement of the vessel using an “electronic map” (stabilized relative to the ground in auto-drifting mode), and in its absence—by means of
an “electronic fairway” or “electronic lines.”
It is important to keep in mind that in most of the existing ARPSs, the switching-on
of stabilization mode of the “electronic map” relative to the ground leads to similar
stabilization of the true vectors of targets, which can distort the assessment of the
situation in case of divergence of ships in conditions of strong lateral drift. In some
ARPS models, this limitation is removed: It is possible to stabilize the “electronic
map” relative to the ground in combination with displaying the true vectors of targets
relative to the water.
In the absence of an “electronic map,” an effective control can be ensured by
means of an external electronic drift-sight.
Taking a rationally chosen navigation landmark for auto-tracking allows not only
to control the leading, fencing, control navigation parameters, but also to systematically determine the ship’s position much faster and more accurately than with
“manual” methods of taking the bearing and distance from the radar. In this case,
it is important to carefully control the location of the auto-tracking strobe on the
selected object (especially, if the landmark is not a point one).
9. Main limitations of ARPS
Since ARPS provides automatic processing of radar signals, all radar limitations are
included as an integral part of ARPS limitations and must be taken into account at
divergence. These are, first of all, the limitations imposed by the used range scale,
the possibility of not detecting echoes from small vessels, interference with radar
detection due to the state of the sea, rain, fog, shadow sectors, etc.
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• possibility of navigation control without distraction from observing the surroundings and without prejudice to other tasks;
• simplicity, visual aspects, reliability of the applied methods, excluding mistakes.
The navigator who manages the vessel (the captain of the vessel or his substitute
senior mate) mainly uses accelerated (pilotage) methods to control the position
and movement of the vessel (leading, control, fencing bearings and distances),
including using radar and ARPS.
The deck officer (officer of the watch, OOW) performs navigational plotting and
periodically determines the ship’s position using normal pilot methods in order to:
• duplication of control in position and movement of the vessel and the timely
detection of possible misses and errors;
• performing the necessary calculations, and obtaining objective data on the ship’s
deviation from the line of a given track, on the course angle, drift angle and ground
speed, on the direction and speed of the total drift, on the distance and bearing to
the point of the beginning of the turn, time to turn, etc.;
• timely providing of the navigator, managing the vessel, with all necessary
navigational information.
When using radar and ARPS, the most effective and efficient method is visual
control of the position and movement of the vessel using an “electronic map” (stabilized relative to the ground in auto-drifting mode), and in its absence—by means of
an “electronic fairway” or “electronic lines.”
It is important to keep in mind that in most of the existing ARPSs, the switching-on
of stabilization mode of the “electronic map” relative to the ground leads to similar
stabilization of the true vectors of targets, which can distort the assessment of the
situation in case of divergence of ships in conditions of strong lateral drift. In some
ARPS models, this limitation is removed: It is possible to stabilize the “electronic
map” relative to the ground in combination with displaying the true vectors of targets
relative to the water.
In the absence of an “electronic map,” an effective control can be ensured by
means of an external electronic drift-sight.
Taking a rationally chosen navigation landmark for auto-tracking allows not only
to control the leading, fencing, control navigation parameters, but also to systematically determine the ship’s position much faster and more accurately than with
“manual” methods of taking the bearing and distance from the radar. In this case,
it is important to carefully control the location of the auto-tracking strobe on the
selected object (especially, if the landmark is not a point one).
9. Main limitations of ARPS
Since ARPS provides automatic processing of radar signals, all radar limitations are
included as an integral part of ARPS limitations and must be taken into account at
divergence. These are, first of all, the limitations imposed by the used range scale,
the possibility of not detecting echoes from small vessels, interference with radar
detection due to the state of the sea, rain, fog, shadow sectors, etc.