Being cruisers and captains, we often emphasize the importance of integrating radar into a vessel’s navigation system as a cornerstone of prudent seamanship. Thankfully, the days of massive, power-hungry radar domes are mostly behind us. Modern pulse compression radar units are lightweight—typically under 11 pounds—and consume minimal power, while providing sharp resolution at both short and long ranges. Why might you want to have radar on your boat? In simple terms, radar helps you “see” what’s around your vessel—even in darkness, rain, or restricted visibility.
Radar—short for Radio Detection and Ranging—works by sending out radio waves from a transmitter. These waves travel through the air, bounce off objects, and return to the radar’s receiver. The system then calculates the time it took for the wave to return and uses that information to determine the object’s distance, direction, and sometimes relative speed. The resulting display usually shows blips or arcs representing boats, land, weather cells, and even large debris. More advanced systems integrate with digital charts, AIS (Automatic Identification System), and multifunction displays (MFDs) for enhanced situational awareness, and these systems are increasingly becoming more affordable and accessible than ever before.
The value of radar becomes especially clear in poor visibility. This is particularly true in places prone to rapid weather shifts or persistent fog. For those of us who regularly cruise the Pacific Northwest during the month of August—affectionately known as “Fogust”—the thick, low-altitude marine fog that frequently settles in from Southeast Alaska to the Salish Sea is a familiar challenge. This kind of fog forms when moist air passes over cooler waters, cooling and condensing into thick, visibility-killing soup, sometimes before you’ve even finished your morning coffee. Having a properly installed and tuned radar means you’re not guessing what lies ahead. You can spot other boats, shorelines, buoys, and yes, sometimes even floating logs, provided they’re big enough and your settings are dialed in. Paired with a good bow watch and conservative seamanship, radar provides crucial backup to your eyeballs when they’re all but useless.
Radar is also helpful in spotting vessels and hazards that are too far away to see with the naked eye or are hidden in blind spots due to waves, swell, or deck-level sightlines. This becomes critical in crowded or narrow waterways, especially when trying to avoid collisions. Many cruisers have added AIS receivers or transceivers to their boats in recent years, which is great progress in maritime safety. But it’s no substitute for radar.
Military and fishing vessels, for example, are notoriously inconsistent about transmitting their AIS position; if they transmit at all. And smaller recreational boats may not be equipped with AIS or might have it turned off. Relying on AIS alone creates blind spots. Radar fills in those gaps. It detects vessels and hazards that aren’t broadcasting a signal, which is exactly when you need the added layer of detection most. AIS and radar together offer the most complete picture of your surroundings. AIS tells you who’s out there. Radar tells you what’s actually out there.
Radar is also invaluable for identifying landmasses, markers, and other fixed obstacles. This is particularly useful when entering harbors or navigating close to shore, especially in areas where aids to navigation (ATONs) may have moved since the last time the chart was updated. In fact, even in well-charted waters, buoys can drift or be repositioned between seasons. Some ocean moorings and larger ATONs can have swing radii of over a mile. Radar allows you to confirm the actual, real-time location of these objects, which is a vital complement to any chart-based navigation.
Radar can also track weather—squalls, rain cells, dense fog banks, and storm systems, helping you prepare for and sometimes avoid deteriorating conditions. This is particularly useful during night passages when visibility is already limited. In the tropics, where squalls often move quickly and without much warning, radar allows you to assess their direction, speed, and intensity. A quick adjustment to your sail plan or course—made with five or ten minutes of advance notice—can make a big difference in comfort and safety. For shorthanded crews or couples standing solo night watches, that information affords otherwise priceless time and peace of mind.
Still, as with any technology, radar isn’t perfect. Smaller targets like crab pot buoys or kayaks may not show up, especially with older or less sensitive systems. Radar images can become cluttered or confusing, especially in coastal areas with lots of interference from landmasses and man-made structures. Multiple vessels in close proximity can create overlapping returns. Ghost targets—false echoes caused by land reflections or equipment interference—can clutter the screen. Learning to interpret what you’re seeing takes time, practice, and familiarity with your particular system.
Offshore, distant targets may first appear as faint, ambiguous blips and can be easy to miss if you’re not paying attention or if your gain and clutter settings aren’t properly tuned. And yes, heavy seas, spray, and rain can reduce image quality. Even modern radar systems benefit from regular tweaking underway. They require an understanding of how to adjust filters and gain settings to distinguish real targets from noise. These aren’t “set and forget” tools, you have to work with them.
Power consumption is another consideration. While today’s systems are far more efficient than older models, some legacy radars still draw significant power and may not be ideal for sailors trying to conserve amp-hours between anchorages. Maintenance also matters. Radar units, like all marine electronics, need occasional calibration and care. We’ve worked with clients refitting their boats who discover that their aging radar dome is not only underperforming but also drawing far more power than they thought. If you’re already upgrading to NMEA2000 systems or replacing an MFD, it often makes sense to upgrade your radar at the same time. Modern units perform better, draw less power, and integrate more easily into your onboard network.
Installation matters, too. A poorly mounted radar dome—tucked into your rigging, mounted too low, or pointed at obstructions—can lead to blind spots and poor returns. And while many DIYers are capable of mounting and wiring a radar unit, this is one area where investing in professional help can pay dividends. Proper alignment, configuration, and integration with your MFD or navigation system can make the difference between a useful tool and a frustrating gadget that rarely gets turned on.
Of course, all of this assumes that you’ve learned how to use it. Radar is not intuitive out of the box. It takes time and repeated use to learn what a squall looks like, how a headland appears versus a vessel, and how to tell sea clutter from a stationary object. You need to push buttons. Play with settings. Experiment in familiar areas during daylight so that, come nightfall or fog, you understand what your radar is showing you. What does a sailboat look like at a quarter-mile? How does a rain cell present versus a fishing boat? These are learned skills. When conditions become challenging, you don’t want your first question to be, “Which button turns this on?”
Increasingly, we hear the argument that AIS is necessary but radar is merely nice to have. And while AIS is certainly a game-changing tool—offering vessel identification, course, speed, and collision alerts—it only shows you what’s transmitting. It won’t show that fishing boat tucked behind a headland, or the drifting log, or the low-slung skiff with no electronics. AIS is like a captain announcing their presence on the radio. Radar is your flashlight in the dark corners of the room. One gives you identity and trajectory. The other gives you presence and scale.
So, is radar necessary or nice? If you stick to day-sailing in clear weather, hopping between familiar anchorages, or staying close to shore in settled seasons, sure, radar might feel like a luxury. You may go an entire season without needing it. But if you sail in shoulder seasons, stand night watches, venture offshore, or explore fog-prone coasts, it’s not just “nice.” Radar’s importance also jumps for those whose cruising schedules are less flexible, when waiting out fog for a day or two isn’t an ideal option. Moreover, it’s smart seamanship. It’s a second set of eyes that never blink, never tire, and never misjudge the distance to a target. It lets you “see” what your senses cannot, and that’s not a luxury. That’s confidence.
For us, radar belongs squarely in the “necessary” column. Not because we use it every hour, but because when it matters, it really matters. And that’s the root of it. Radar isn’t just another gadget, it’s a tool that expands your awareness in the moments that count. The moments when your eyes are useless, your ears are guessing, and you need near-absolute clarity. Once you’ve relied on radar in earnest, it’s hard to imagine cruising without it. So invest in learning it. Tune it. Use it. Trust it. But always pair it with good seamanship and a well-trained crew. After all, your sharpest tool is still the human brain. But it’s nice to give it backup.
Gio and Julie of Pelagic Blue lead offshore sail training expeditions and teach cruising skills classes aimed at preparing aspiring cruisers for safe, self-sufficient cruising on their own boats.
