On shore, 6 February 2010
Mates were in high demand during World War II.
The International Regulations for Preventing Collisions at Sea are a cornerstone of safe watchkeeping. Safety requires that one live these rules and follow the principles of safe watchkeeping. Maximizing bridge teamwork, including Bridge Resource Management is an emerging focus in watchkeeping.
The main purpose for Radar and Automatic Radar Plotting Aids (ARPA) on a ship’s bridge are to move safely among other vessels. These tools help to accurately judge information about prominent objects in the vicinity, such as:
• range, bearing, course and speed
• time and distance of closest point of approach
• course and speed changes
These factors help the officer apply the COLREGS to safely maneuver in the vicinity of obstructions and other ships.
Unfortunately, radar has a number of limitations, and ARPA inherits those limitations and adds a number of its own. Factors such as rain, high seas, and dense clouds can prevent radar from detecting other vessels. Conditions such as dense traffic and course and speed changes can confuse ARPA units. Finally, human errors such as inaccurate speed inputs and confusion between true and relative vectors add to the limitations of the radar/ARPA suite.
The radar operator must be able to optimize system settings and detect divergences between an ARPA system and reality. Information obtained from radar and ARPA has to be treated with scrutiny: over reliance on these systems has sunk ships. The officer must understand system performance. Examples include limitations and accuracy, tracking capabilities and limitations, and processing delays, and the use of operational warnings and system tests.