Can somebody explain to me the mechanics of Radar Plotting?

Answer 1

Both answers given are good, so I will just throw in a brief input on how RADAR works. RADAR is an acronym for radio detection and rangeing. It works on the Doppler effect. Doppler said that if the source of the wave is approaching the frequency will seem to increase, and the opposite. So as a wave(the size of a microwave) is sent out and reflects back, its frequency is changed. Since we know the rate that electromagnetic waves travel, the difference in frequency can ttell us the speed of an approaching object as well as its presence.

Answer 2

Automatic Radar Plotting Aid, ARPA, gives a maritime radar the possibility to follow targets resembling other ships, calculating their course, speed and possible collision with own vessel.

Development of ARPA started after the accident when the Italian liner SS Andrea Doria collided in dense fog and sank off the US east coast. ARPA radars started to emerge in the 1960's, and with the development of microelectronics such systems are now available even for small yachts.

Retrieved from "http://en.wikipedia.org/wiki/Automatic_Radar_Plotting_Aid"


Here's a link for detailed contents:
http://www.pilotsbooks.com/radar_and_satellite_interpretation.htm

Answer 3

If you mean manually, you just watch a target over time to figure it's course and speed and then continue that line to figure where it will be at what time.