If you're feeling a bit confused at this point, consider that we haven't used one single acronym yet. And when it comes to radar (which, incidentally, stands for Radio Detection And Ranging,) there are plenty. Here are the important ones:
- CPA: Closest Point of Approach. This is the point at which your boat and a target will be the closest, assuming neither changes course nor speed.
- EBL: Electronic Bearing Line. The EBL on a radar allows you to accurately navigate with a radar and to determine the exact bearing to different targets.
- MARPA: Mini-Automatic Radar Plotting Aid. MARPA functions help identify and track a target's speed, bearing, CPA, and TCPA and often allows you to associate these with a proximity alarm.
- TCPA: Time to Closest Point of Approach. TCPA describes how long it will be before your boat and a target reach CPA, assuming neither changes course nor speed.
- VRM: Variable Range Mark. This is exactly what it sounds like: a marker that enables you to determine the range to different targets.
LCDilemma
All of this radar knowledge is great, but about now, there are undoubtedly people rolling their eyes and groaning. All they really want to know is how to look at that LCD screen and distill what's a channel marker, what's another boat, and what's land. For you folks, investing in a system that overlays your radar returns on your chartplotter screen is probably a good move. (See photo below.) It eliminates an awful lot of the guesswork, as long as the overlay doesn't add to the confusion. Work with one to see it if works with you.
It's much easier to tell what you're seeing on screen when your radar is overlaid on your chartplotter. The red areas show the radar "echo" and clearly delineate the coastal outline.
Beyond that, there are several things to keep in mind. First off, before you try discriminating between those blips and blobs, zoom in as much as possible. For most of us, the majority of the time what we're really concerned about lies within a mile or two of our boat. Looking at the radar set to a farther range only reduces the size of the returns you're concerned about and adds unnecessary information. Long ranges, however, can detect squalls and enable you to cruise around them, can detect landfalls, and have other uses, so don't just set it for short ranges.
Secondly, don't view radar on a split screen but instead give it as much LCD territory as possible. The bigger the picture you're looking at, the easier it will be to figure out what's what. And when you really need radar, looking at something like the fishfinder should be the least of your concerns, so dedicate that entire MFD screen to what counts. Overlays of information can cause problems or solve them, so as we said before, see what works for you.
Finally, remember that some thoughtful interpretation is often necessary. Three strong returns that remain static and are lined up neatly in a row are likely to be a series of channel markers; weak returns that come and go are often poor targets like small fiberglass boats; and two targets keeping pace close to each other could be a tug and its barge. Accurately reading returns like these requires a different sort of algorithm — the one that's in your own brain.
Some newer radars, like Garmin's Fantom, apply Doppler technology to accurately track moving targets.
Yes, it will take some practice to accurately and proficiently determine what's on the LCD screen. But we do have one very big piece of good news for you: Today's modern radars have such advanced processing powers that you'll rarely need to adjust anything. Gone are the days of constantly fiddling with sea state and clutter adjustments to get a clear picture on the screen. Leave your unit on auto mode and in most situations, it can do a better job than you or I at presenting the best possible picture. And whether you're trying to navigate through a pea-soup fog or the inky darkness, that one fact alone will make using your radar far easier than ever before.
Never overestimate radar, or any other equipment, however. For example, most radars will not see through significant amounts of rain, and you may find yourself running blind if you've only relied on radar as you approach the storm. Also, it's very important to practice steering to radar. Refresh rates of the best screens are less than what we're accustomed to with our vision. And loss of horizon, shorelines, and other external data can drastically affect orientation, distance perception, turn rates, and other things. Practice running on radar alone when it's safe, in good weather, to learn what it can be like in pea soup.
You may be very surprised