The Basics of Using Radar

Many boat owners know that their radar system will show them other objects, but they don’t really know what those objects are.  They can’t tell the difference between other boats and buoy markers, for example.  That’s because radar systems can be very complicated.  However, by understanding the basics, you can learn how to make the most out of your radar.

Radar Basics

Many boat owners have no idea how radar even works.  It’s actually somewhat simple in concept.  Imagine the moving line on the radar screen as a flashlight.  As it turns, it’s cutting through the darkness.  Suddenly, the light hits something!  That item becomes a blip on the radar screen.  Instead of light, of course, the radar is using something different—a microwave pulse that reflects off of solid objects.  When that pulse is returned and detected by the radar’s antenna, the computer then calculates the distance to the item the pulse was reflected off of.

There is one type of radar that doesn’t work this way.  Broadband radar, which is relatively new when compared to traditional radar, sends out a wave of continuous transmissions instead of pulses.  As this wave moves further away from the radar and hits an object, its frequency increases.  The radar computer then calculates the difference between the original frequency and the reflected frequency to determine how far away the object is.

Interpreting the Results

Once the radar determines that there is an object out there and knows how far away it is, it creates a small blip on the screen.  The size of the blip can help you determine how large the object is—generally, the bigger the blip, the larger the object.  However, it’s not as simple as saying that a blip of X size represents an object of Y size.  This is because the height, shape, and even the material of the object all affect how the radar sees it.  That means a small sailboat may appear on radar to be the same size as a larger motor boat.  Some smaller boats, especially those made out of fiberglass, may not even appear on your radar at all.

Factors in Determining the Power of Radar

The power of the pulse sent out by radar also plays a part in how well the system can see.  The more wattage the radar has, the farther its pulses can reach.  Radar that’s fairly low wattage (a few kilowatts) typically cannot detect objects that are more than a couple dozen miles out, and it’s very likely to miss little fiberglass crafts that are only a few miles away.  Double the wattage and suddenly it can “see” about 30 miles away.

However, power is not the only factor.  The width of the beam is also important.  A narrower beam can pick up some targets from longer distances than a wider beam can.  In the flashlight analogy, a narrow beam is a thin spotlight, while the wider beam is a floodlight.

Finally, you have to remember that the Earth’s curvature plays a major part in radar.  Because the beams radar sends out don’t curve, they can’t see anything that sits over the horizon.  While antenna that are positioned higher up will be able to see farther, they’re still limited by the height of the object and by the Earth’s curvature.  Even the most powerful radar is still restricted by these limitations.

Advances in Technology

While it’s good to understand how radar works, it’s also good to know that advances in radar technology have made today’s equipment so advanced that you can simply set them to their fully automated modes and go.  Just check the screen every now and then to see what’s out there, and you shouldn’t have to worry.  Of course, these advancements mean modern radar has a lot of different features, so it’s always worth taking the time to learn your particular system.