ARPA (Automatic Radar Plotting Aid) is a crucial ship navigational tool. It automates the process of tracking other vessels and landmasses, significantly enhancing safety at sea. By calculating course, speed, and closest point of approach (CPA), ARPA helps mariners make informed decisions to avoid collisions and other hazards, according to Marine Insight.
Real-Time Data
By providing real-time data on the speed, course, and position of other vessels, ARPA significantly reduces navigators’ workload and improves situational awareness, especially in congested or restricted waters.
The development of ARPA was driven by the need to improve maritime safety and efficiency. Traditional radar systems required manual plotting of targets, which was time-consuming and prone to human error.
The advent of digital technology in the late 20th century allowed for the automation of this process, leading to the development of ARPA systems. These systems were designed to automatically track targets, analyze their movements, and provide valuable collision avoidance information.
The primary function of ARPAs can be summarized in the statement found under the IMO Performance Standards. It states a requirement of ARPAs: “to improve the standard of collision avoidance at sea: Reduce the workload of observers by enabling them to automatically obtain information so that they can perform as well with multiple targets as they can by manually plotting a single target”. As we can see from this statement the principal advantages of ARPA are a reduction in the workload of bridge personnel and fuller and quicker information on selected targets.
A typical ARPA function gives a presentation of the current situation and uses computer technology to predict future situations. An ARPA assesses the risk of collision and enables the operator to see proposed maneuvers by own ship.
Parameters Tracked
ARPA tracks the following parameters and has the following functionalities:
1.Motion Radar Presentation
True and Relative Motion Display: Capable of presenting both true and relative motion radar information for enhanced situational awareness.
2.Target Acquisition
Automatic and Manual Acquisition: Supports both automatic and manual target acquisition to ensure comprehensive tracking of all relevant targets.
3.Digital Read-Out
Detailed Target Information: Provides digital read-outs for acquired targets, including:
- Course
- Speed
- Range
- Bearing
- Closest Point of Approach (CPA)
- Time to Closest Point of Approach (TCPA)
- Bow Crossing Range and Time
4.Collision Assessment
Enhanced Display: Directly displays collision assessment information on the Plan Position Indicator (PPI), utilizing:
- Vectors (true or relative)
- Graphical Predicted Area of Danger (PAD) display
5.Trial Maneuvers
Simulation Capabilities: Enables the performance of trial maneuvers, including:
- Course changes
- Speed changes
- Combined course and speed changes
6.Navigation Stabilization
Automatic Ground Stabilization: Offers automatic ground stabilization for precise navigation purposes.
7.Rapid Processing
Enhanced Processing Speed: Processes radar information much more rapidly than conventional radar systems, though it remains subject to the same limitations.
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Source: Marine Insight
