Radar (Marine)
Radar (from radio detection and ranging) is a shipboard system that detects other vessels, landmasses, navigational marks and hazards by transmitting radio waves and displaying the echoes returned from objects around the ship. It shows their range and bearing on a display, giving the watchkeeper a picture of the surrounding traffic and coastline day or night and in poor visibility — making it essential to safe navigation and collision avoidance.
Modern marine radar includes ARPA (Automatic Radar Plotting Aid), which automatically tracks targets and computes their course, speed and closest point of approach (CPA), warning of collision risk. Radar is a core piece of bridge equipment, used together with ECDIS, AIS and visual lookout, and its proper use is central to complying with the COLREGs, especially in restricted visibility. Its carriage is required by SOLAS. Radar is one of the most important tools for keeping a proper lookout and avoiding collision, and remains fundamental to bridge watchkeeping despite the addition of newer aids like AIS. It is indispensable to safe ship navigation.
Radar is the watchkeeper's eyes in fog and darkness — detecting ships, land and hazards and, through ARPA, warning of collision risk before it develops. It is central to keeping a proper lookout and complying with the COLREGs, and remains a fundamental bridge tool alongside ECDIS and AIS. Safe navigation in poor visibility depends on it.
What is ARPA?
Automatic Radar Plotting Aid — radar that automatically tracks targets and computes their course, speed and closest point of approach to warn of collision risk.
Why is radar essential?
It detects surrounding vessels, land and hazards day or night and in poor visibility, making it vital to lookout and collision avoidance under the COLREGs.