Reflections on Radar
By Tamia Nelson
May 12, 2009
A gentle rain had been falling on and off for three days. When it finally let up, I grabbed my camera and hightailed it down to The River, planning to hike along the portage trail and check out the rapids. The passage of a front always makes for great photos, and with the promise of shafts of sunlight breaking through the clouds, I was hoping for some dramatic shots of the rushing waters. As luck would have it, though, the sun continued to hide his face. Still, the colors were saturated and there was plenty to shoot, so I made my way downstream along the trail. Not far ahead was the first of a series of staircase falls. The River was in flood, or near enough as made no difference. Hundreds of tons of water were pouring over the drop every second. Long before I could see the falls, I could hear the river roar and feel the ground tremble beneath my feet. Then I rounded the final bend in the trail, and a chill, wind-driven mist rose to greet me. A few more steps and the falls came into view, wreathed in tendrils of fog. What a great photo! I raised my camera, aimed, and…nothing happened. The NiMH batteries in my camera had quit on me without giving notice—something they're prone to do, I'm sorry to say—and that was the end of the photo shoot. I'd been in such a hurry to reach The River that I'd neglected to bring any spares.
Still, I made the best of things, staying by the river to watch the mist thicken until fog shrouded the entire valley. By the time I was ready to hike out, even the quiet pool above the dam was obscured. But someone was on the water. I could hear the characteristic metallic thunk of a paddle shaft striking the gunwale of an aluminum canoe. (Not for nothing has aluminum been labeled "boomalum.") I couldn't see the boat, but I guessed that the invisible paddler was a local angler testing the snowmelt-swollen waters. Clearly, stealth wasn't part of his game plan.
This got me thinking about the times when I'd been caught on the water as fog closed in. Fog has many personalities. Sometimes it's as wispy as a gauze curtain, rippling languidly in a summer breeze. At other times it's brooding and blowsy. And then there are the worst of times—the times when fog wraps an impenetrable wall around you and your boat, shrinking your world to a circle not much bigger than the length of a paddle, a world with neither sun nor shore, in which there are only the swash of surf and the cries of birds to remind you where you are. This is fog stripped of any romantic associations. All that's left is…
And there's danger even when there are chinks in the wall around you. Yes, when the murk isn't total, you can see out. At least you can get a glimpse of the larger world from time to time, often enough to spot familiar landmarks or seamarks—if there are any close at hand, that is. But can others see in? That's the important question. If you're on Golden Pond, with only loons for company, there's little cause for concern. But what if you're in a busy harbor? Or paddling across a heavily traveled shipping lane? Or suppose you find yourself in the middle of a bass tournament, with dozens of competitors racing from one honey hole to the next just as fast as 150 captive horses will take them, every angler driven to win and navigating on GPS and faith? What then?
Well, to begin with, you try to make yourself as visible as possible. (The best strategy is avoidance, of course. But fog doesn't always appear—or disappear—on schedule.) Bright colors are always a good idea, and that goes for your boat and paddle, as well as your PFD and jacket. Clipping a strobe to your PFD helps, too, although this common practice is outlawed under the International Rules of the Road, except in cases of "immediate danger." (It is permitted under the Inland Rules, subject to certain technical requirements.) Nor does it hurt to be heard as well as seen. There's always your trusty whistle to fall back on, though you can also buy portable foghorns, many of which are small enough for paddlers to carry and use. Some of these employ lung power. Others rely on compressed gas. The smaller gas-powered horns are often used by urban cyclists, so if your local outfitter doesn't carry what you need, try a bike shop. Whatever noisemaker you choose, however, the International and Inland Rules, along with state and provincial laws modeled on them, prescribe specific signals for different classes of vessels operating "in or near an area of restricted visibility," a condition which includes fog, as well as "mist, falling snow, heavy rainstorms, [and] sandstorms." Paddlecraft aren't specifically mentioned in the Rules, but they probably ought to be classed with sailing vessels. The prescribed sound signal? "One prolonged [four- to six-second blast] followed by two short blasts," at "intervals of not more than two minutes."
So far, so good. But this strategy has an important drawback. Hooting your horn (or tweeting your whistle) every few minutes can make it harder to hear what's going on around you, and attentive listening may well be the paddler's best defense in fog. Power-driven vessels are required to sound a single "prolonged blast" at intervals of not more than two minutes, though there's nothing to say they can't make this signal more frequently, and many do. The skippers of licensed commercial vessels can usually be relied upon to follow the requirements in the Rules to the letter. Recreational boaters cannot, however. Luckily, there's always engine noise…
But suppose you opt to sound off, anyway, in addition to lighting up. Is this enough? Almost certainly not. A canoe or kayak is just a speck in the sea when seen from the bridge of a freighter, even when visibility is good, and you can't rely on the watch on deck hearing the tinny tweets from your little whistle above the throb of a ship's great engines. And even if you are seen or heard, it may be too late. A heavily laden ore carrier can take a mile or more to come to a stop after ordering Crash Full Astern. Big ships aren't squirt boats, after all. The can't stop (or pivot) on a dime.
So what's left? Would a radar reflector help? That's a question "RP" asked us not long ago:
As a prairie-dweller with an overactive imagination, I was wondering whether any of your coastal readers may be able to comment about the feasibility of using helium- or hydrogen-filled, aluminized-plastic balloons as makeshift emergency radar reflectors.
Would monofilament-tethered, sufficiently long balloons, of 3- or 10-cm diameter (the wavelengths of X- and S-band radars) work anywhere close enough to act as decent reflectors if one were caught suddenly in fog—or for SAR [search-and-rescue] purposes?
Good question. But I didn't know the answer. Neither did Farwell. So I took the matter up with an expert. Kayaker and In the Same Boat reader Whit Patrick is a retired US Coast Guard officer and former station commander. If anyone could answer RP's question, I figured Whit could. And I was right. Here's what he had to say:
If you were to fill a metallic-coated balloon as full as possible and mount it on a stick, it would probably work at 50 to 60 percent the effectiveness of a stiff metal plate of the same size. Once the actual or relative wind began to distort the balloon, the effectiveness would decrease. Mount the balloon on a piece of cord and create some relative wind by paddling, and I'm confident in saying the effectiveness would be very, very low.
If you take a "Mylar®" birthday balloon and walk down the street with it trailing on a four- or five-foot cord, you'll get an idea of how it will behave behind the boat. If you add just a couple of knots of actual wind to the mix, you have no idea the direction or distortion of the balloon.
Try bouncing marbles off of a Mylar balloon that is 80 percent inflated. I think you'll see that the returns are going to be unpredictable and inconsistent. [T]he best radar reflectors have lots of flat surfaces. That is why navigational buoys from large, unlighted classes right up through the very large entrance buoys have metal plates creating a large reflective target as part of their structure.
Another thing is that you do want the surface to be hard so it doesn't distort and affect the reflectivity for the radar waves. Think about looking at yourself in a nice clean, smooth mirror. You get a good representation of what you look like because the light waves aren't redirected by surface irregularities. Now go to a smooth section of standing water in a small pond. Still a good reflection, but not as good as the mirror. Finally, go to the same spot on a breezy day where there is a little inch-high ripple. You won't see yourself at all because the light waves are being cast every which way.
The other thing that will make the balloon too ineffective to be considered is that as you move faster across the water, it is going to float closer and closer to the water's surface and simply "disappear" into the radar reflection from the water.
So, what's the upshot here? Is it true that party balloons can have no place in paddlers' emergency kits? Well, no, not necessarily. Whit wasn't prepared to go that far. His conclusion?
[I]t might be a good idea to save those Mylar balloons and put a couple of deflated ones in your deck bag or PFD pocket. They would, I think, be a pretty good emergency radar and light reflector if they were taped onto a paddle blade. Then, in foggy situations or nighttime situations where you can lift one blade up for 30 seconds or so every three minutes, it might work better than nothing!
OK. Metalized party balloons aren't great radar reflectors, but they'd be better than nothing in an emergency—provided that you taped them to your paddle blade instead of inflating them and towing them behind you. This answered RP's original question, but it left me with another: Is there a better way to hoist a radar reflector from a canoe or kayak? And what are the chances that a radar operator or watch officer would actually pick up a kayak, SOT, or canoe under conditions of reduced visibility? So I wrote to Whit again. And here's what he had to say:
Some things that have been used with varying success include bundles of tin foil suspended from a kite, or a whip antenna (like the supports ATV riders use to hoist visibility flags) with a lightweight, 90-degree radar reflector mounted at the top. Either MIGHT increase the chances you will be seen by an attentive radar operator.
There are, however, a great many variables involved in what will work to make you visible on radar. First, did the operator tune the radar correctly? Is the operator watching the radar at the critical time? Can the operator pick out a tiny target concealed in the scatter of the sea or weather return? Think about how often large vessels run into each other in clear, calm weather. It's scary.
[Even if you're avoiding shipping lanes, you're not necessarily home free. Recreational craft and fishing boats present problems, too.] Does the height of the vessel's bow relative to the position of the bridge obscure an area from visual or radar sight? Is the vessel running under "Iron Mike" [mechanical self-steering]? That really worries me with yachts and commercial fisherman who tend to believe that their GPS will always work.
As far as visibility in fog or bright sun during the day, I think the best device is colored smoke, [though this should be reserved for emergency situations, when immediate assistance is required]. It provides good contrast in fog and creates an odd patch of shadow in bright sun where the kayak might be obscured by glare. Come to think about it, maybe I should go and buy a few day and night flares myself!
What's the bottom line? Paddling in or near areas of restricted visibility involves an irreducible element of risk, and that risk rises as the traffic increases. Does this mean you have to languish ashore on all but clear, sunny days? Certainly not. But it does mean that you can't depend solely on technology to keep you safe. Foghorns, smoke flares, strobes, and, yes, radar reflectors—whether improvised or purpose-built—all have a place in the prudent paddler's gear. Yet nothing can equal the safety equipment you're born with: eyes, ears, and brain. Not to mention the still, small voice that counsels caution whenever danger threatens. You ignore it at your peril.
When all is said and done, therefore, probably the best advice to worried watermen is that given by the old boatman in J.M. Synge's classic The Aran Isles:
A man who is not afraid of the sea will soon be drownded,…for he will be going out on a day he shouldn't. But we do be afraid of the sea, and we do only be drownded now and again.
There you have it. Good advice, honestly stated. A testament to self-reliance and the intelligent use of fear, coupled with an acknowledgment of the unarguable power of the implacable sea—the power of all water, everywhere, both moving and still. It's not a comforting message, I suppose, but it is a realistic one, and curiously liberating. That's my take, anyway.