Radar
Radar
Radar stands for Radio Direction And Ranging. The acronym was coined by the U.S. Navy in the 1940s, just prior to the U.S. entering World War II.
Radar Animation
While the electronics of radar are pretty complicated the principle is quite simple. When you send out a signal and measure the time (t) for an echo to come back, the distance (D) to the object reflecting the signal is found by:
D= c x t/2
Where c = the speed of the signal. And in the case of radio waves, c = the speed of light = 299,792,458 m/sec.
It’s pretty amazing that we have electronics that can measure time differences at those kinds of speeds. For example, if an object is 1 nautical mile (1852 m) away, the time for the reflection to come back is:
t= 2 x D/c
= 2 x 1852 / 299,792,458
= 12 microseconds
= 12 millionths of 1 second
= wow!
But even better than that, the electronics can distinguish things that are 10 meters apart from the time differential. Double wow!
With radar, you can “see” weather systems approaching, land masses, and other vessels even if you cannot see them. Just a note, however: the Rules for Prevention of Collision at Sea DO NOT allow for the replacement of a visual lookout with radar (or AIS for that matter).
Even if your vessel does not have radar, you can utilize weather radar information broadcast on the Internet with your handheld phone or tablet. If you see dark clouds, you are well advised to pull out your device and view the local weather radar.
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Anecdote as I remember from my Dad relaying a WW II Radar story: “As the radio operator on our DC-3 supply plane, I remember one night flying back to base after a long flight of dropping supplies at the front lines. The weather had turned nasty—clouds thick as pea soup, and no stars in sight to guide us. I was sitting at my station, listening intently to the crackle of the radio, trying to catch any morse signals that might help our navigator plot a course home. Suddenly, the pilot called out, ‘We’ve got a radar contact!’ I looked up, and although I couldn’t see it, I knew we were relying on this new technology to find our way. The radar wasn’t on our plane, but the ground stations were picking us up and sending coordinates back through Morse code. I quickly jotted down the numbers and passed them to the navigator, who adjusted our heading. It was like having an invisible lighthouse in the storm, guiding us home safely. I didn’t fully understand how it worked back then, but I knew that radar was something special—something that kept us in the air and got us home in one piece.” probably I was born and am alive today on this planet because of Radar technology. |
