What Is Marine Radar?
A sensor that maps the surroundings by the echo of radio waves — the one eye that sees non-broadcast targets AIS cannot detect, such as dinghies, buoys and squalls.
Radar is a sensor that reads the echo of radio pulses sent from a rotating antenna and plots the direction and distance of nearby objects. Night and fog are why radar exists. It complements AIS; it is not an alternative to it.
The table below shows why the two are used together.
Radar - AIS together
Feature | Radar | AIS |
|---|---|---|
What it detects | Any object returning an echo | Only vessels transmitting AIS |
Non-broadcast boat/dinghy | Can see | Cannot see |
Buoy, squall cloud | Can see | Cannot see |
Identity information | None | Name, speed, course |
AIS only shows craft that are transmitting. Radar also picks up a fishing dinghy without AIS, a buoy, and even an approaching squall cloud. In Göcek, sudden loss of visibility is rare, but when it happens radar is the difference between stopping the passage and carrying on.
An unadjusted radar screen will either look empty or like a snowstorm; learning the gain and sea clutter settings takes only a few hours’ practice. The guard zone feature is the quiet watchman on night anchor watch.