More Reflections on Radar
By Tamia Nelson
June 9, 2009
Paddling in fog—or at night, or under any other condition of restricted visibility—can be an eerie experience. It can also be dangerous, particularly if you're sharing a waterway with merchant vessels or other commercial craft. Even on clear, sunny days, it's easy for a skipper or deck officer to fail to spot a kayak or canoe in a busy harbor. That's why many paddlers look for ways to stand out in the crowd. And radar reflectors are among the tools we use. I first explored this subject last month, in an article entitled "Reflections on Radar." Not surprisingly, it generated quite a lot of buzz among In the Same Boat readers who frequent heavily traveled waters. In fact, the column provoked so much thoughtful comment that I decided to revisit the subject. So if you're worried about being a small speck in a large expanse of open water, this one is for you. Let's begin with a discussion of…
Smoke and Mirrors (Not to Mention Strobes)
We paddlers are the littlest guys on the block, and if we want to play with the big boys, we need to know the rules. Or in this case, The Rules, aka the Nautical Rules of the Road, as Cliff Dillmann of Marysville, Pennsylvania, lost no time in reminding me:
Interesting article on radar reflectors, and I agree. Even the lightweight reflectors retailed for sail and power boats have been questioned as to visibility.
One point is worth emphasizing: Smoke signals and strobes are intended to signal emergency and request rescue. Some now argue that strobes are permissible, but I have never seen any indication that a smoke signal is less than a full SOS. Its use to do no more than indicate position is likely a violation. [NB The Inland Rules allow the non-emergency use of certain strobes "to attract the attention of another vessel," but this exception is not recognized in the International Rules. And neither Inland nor International Rules permit the use of orange smoke as anything other than a distress signal. —Editor] Of course, if the barge is headed for you anything is appropriate. But at that point smoke is too slow to start and would usually be hidden by the bow, as you have noted.
A powerful flashlight pointed directly at the bridge is the most visible thing a canoeist or kayaker can do at night. Cheap and waterproof ones start at USD20. A mirror does the same in daylight. One must practice techniques for aiming both. Try it across a river or lake, coordinating by cell phone with a partner on shore.
You did not mention marine radio. Waterproof, handheld, and even floating units are available at low cost. Anyone can announce their position and intentions and can call the approaching vessel. Sécurité calls on VHF Channel 16 are urgent informational announcements. They are not distress calls and will be respected. For instance, if a sécurité call is sent when a vessel is about to commit to an inlet, it welcomes a response from a larger ship that is already committed to that passage. Having a GPS—also handheld and waterproof—for announcing exact location, if needed, makes sécurité even more effective. The newest digital marine radios can do both.
One more side point on cell phones. In a real-life emergency involving a small fire no 911 operator near the shore of the Chesapeake Bay was able to use GPS coordinates even to find out which dispatch district the fire was within. Apparently they have no access to a topographic map or nautical chart with coordinates.
A cautionary tale, that, coupled with some very good advice, and to eliminate any ambiguity I've edited my original radar article to underscore the proper role of orange smoke. Light and sound signals—including flashlights, strobes, and mirrors—were also the subject of an earlier column. I've touched on the use of marine radios before, too. See, for example, "Singing Over the Wine-Dark Sea." That said, it's high time we took another look at the subject. Stay tuned. And thanks for the heads-up, Cliff. Much appreciated!
Moving on, now: If you're a paddler or dinghy sailor and you've never been aboard a larger craft, then you might be interested in seeing what the view is like…
From the Wheel of a BIG Boat
When you're sitting in a canoe, kayak, or SOT, you're about as close to the water as you can get without diving in. That's why experienced river runners sometimes stand up in their boats when checking out a tricky drop. The extra height gives a much better picture of what lies ahead. Still, even if your eyes are six feet above the surface of the water, you can't see as much as you might think. The same thing is true from the wheel of a sailing yacht or motorsailer. These are truly big boats, and they're a common sight in harbors and along many recreational waterways, but their size doesn't guarantee that the skipper has an unobstructed view. And radar isn't necessarily the answer, either, as reader Mike Euritt of San Rafael, California, pointed out:
In addition to being a paddler, I've recently taken up mother-shipping with a 37-foot motorsailer. The boat came with a late 1980s-vintage radar that I have been trying to learn to use. I frequent the boating boards daily, as I do Paddling.net, and the subject of radar does come up. I've saved some very informative links for radar reflectors, as well as those on radar use.
The first problem with radar on any boat big enough to support the radar array is this: Is the radar turned on?
Second, is anybody trained in using the radar? That is, trained (either self-taught or school taught) to be able to adjust the radar to make the best use of the device.
Third, is anybody watching?
Assuming we have a yes in answer to each question, then we have to work on the target. The radar on many older boats often isn't capable of seeing a good-sized fiberglass or wood yacht. Forget about seeing a paddler. It is my understanding that the new generation of digital radar might be able to, but I'm not yet convinced. I'm not clear from my experience and reading if my (37-foot) boat is visible, and I'm still working on being able to track the channel markers as I navigate the 2.5-mile channel from harbor to open bay. Just looking for telephone poles with reflectors supposedly optimized for radar amongst the clutter is a harder job than I had imagined.
I've come to the conclusion that a personal Automatic Identification System (AIS) transponder is the only sensible choice, aside from exercising prudence in choosing where I sail and paddle. The AIS claims to notify me of the presence of radar, alerting me to the radar's transmission and giving me time or awareness to get out of the way of any larger vessel.
It would be very interesting to see a test of modern radar and how small an object it can see, as well as determining if AIS is actually useful for a paddler.
Thank you for your article. We do need to think about such things.
Mike raises several important questions, and because he has experience as both a paddler and a big-boat sailor, he brings an unusually broad perspective to the subject—a perspective shared by the people at the Maine Sea Grant College Program (University of Maine, Orono) whose…
Research on Sea Kayaker Visibility…
Was the topic of a letter I recently received from Kathleen, another reader who'd found my original article of interest:
Just read your excellent article and thought you might like to take a look at this report from the people at the Maine Sea Grant. [NB The link takes you to 2.5-MB PDF. —Editor]
Now that was timely! So I took a look. And I liked what I saw. The folks at Maine Sea Grant have gone the distance, with the able assistance of the US Coast Guard and members of the Maine Association of Sea Kayak Guides and Instructors (MASKGI). The summary of their findings, an eight-page report entitled "Radar, Reflectors and Sea Kayaks: A Visibility Study," is must reading for any open-water boater who ventures beyond Golden Pond—or who ever plans to do so. The accompanying slide show is also well worth a look. Credit where credit is due: We have Information Technology Coordinator Jenny Peters to thank for making the report and slide show freely available to anyone with a mouse and a few minutes to spare. It's not often that tax dollars are put to such good use!
Now here's a sneak preview of the study's findings:
- Larger kayaks show up on radar better than smaller ones.
- There's strength in numbers. Groups ("pods") of kayakers traveling close together are more likely to be detected than a solo kayaker, even if the solo boater has a radar reflector.
- A kayak is easier to spot on radar if it's broadside to than if it's stern to or bow on. In other words, the angle the kayak makes to the radar-equipped vessel determines the strength of the return signal, and therefore the kayaker's chances of being spotted.
- The more angular a radar reflector is, the more effective it is. Corners are good, in other words, and the more corners the better.
- One of the most effective radar reflectors in the study was—wait for it!—a homemade tinfoil hat of the type more often associated with…well…individuals seeking protection from mind-reading aliens. (This gives a new meaning to the phrase "dress for success," doesn't it?)
- Effective reflector or no, however, the farther a kayaker is from a radar-equipped vessel, the less likely it is that he'll be spotted. Kayakers who were more than ½ nautical mile away produced a weak signal at best. This wouldn't give the skipper of an approaching motor vessel much time to register their presence, let alone react. A vessel under way at 15 knots will travel half a nautical mile in just two minutes.
So it's no surprise that the Sea Grant study also affirmed the importance of radar operator training and experience, in addition to several technical factors. Here are a few of the relevant findings:
- The strength of the reflected signal ("return") is the primary consideration in determining whether or not a kayak is detected.
- If you want to be picked up on radar, waves and chop are not your friends. Reflections from waves and rain—so-called "clutter"—affect target visibility, and while the set's operator can adjust the gain to eliminate the spurious signals, the result is reduced overall sensitivity. The situation is even worse if the radar-equipped vessel is rolling or pitching wildly, or if the bow is elevated.
- All other things being equal, high antennas "see" farther than low antennas.
- Perhaps most importantly, radar is only effective if it's being watched.
Finally, here are the researchers' conclusions, beginning with their…
Recommendations for Paddlers
- Any radar reflector is better than none, but only if it doesn't hamper your ability to paddle. An aluminized "space blanket" can be a reasonably effective reflector when draped like a cape over your shoulders, for instance, but it won't do much for the efficiency of your stroke.
- Mount your reflector as high as possible, but not so high as to impair your boat's stability or impede self-rescue.
- Paddle with friends. A close-knit pod of kayaks is more likely to be noticed than a solo boater.
- Cross open water at narrow channels with known navigation references, and make a sécurité call on VHF Channel 16 (or the preferred local alternative) to advise transiting vessels of your intent, being sure to give exact course and position.
They then add a few…
Reminders for Big-Boat Operators
- Keep a regular radar watch and observe the screen through multiple sweeps each and every time.
- Adjust your radar's clutter and gain settings for optimal resolution.
- Monitor VHF Channel 16 for sécurité calls.
- Reduce speed in areas with heavy recreational traffic.
That's it. Good advice for the skippers of all vessels, from kayaks to supertankers, thanks to our readers and the folks at Maine Sea Grant.