Re: [Paddlewise] Kayak Visibility

I guess this would be a good time to talk about the ability of radar to see
(or "paint") a kayak in various conditions and from various vessels.

There are four major factors involved in seeing kayaks from radar equipped
vessels:

1. Sea state;
2. Radar power, state of tuning, and antenna location and orientation;
3. The "coefficient of reflectivity" of the kayak; and,
4. The attention factor of the radar observer.

In simple terms, the higher the waves the more difficult it is for a radar
system to "see" a kayak - or virtually any vessel less than about 50 feet.
Once the wind starts creating whitecaps and blown spray - all of which
attenuate electromagnetic signals at microwave frequencies - things get
appreciably worse. This is due, in part, to the extremely tiny wavelength of
radar signals. These wavelengths are so tiny that they are scattered by the
water droplets in the spray so that relatively few of those that are
reflected by any object sitting low in the water make it back to the radar
antenna to be displayed on the screen. And it has to be displayed on the
screen for someone to see it.

Another problem with a higher sea state is that operators tend to turn down
the sensitivity of the radar in order to reduce "clutter" or noise. Most
radar observers are really looking for other ships not kayaks, and the noise
caused by the whitecaps and spray can be reduced without causing any
appreciable loss in sensitivity required to detect ships. Detecting kayaks,
on the other hand, gets lost completely. And remember that your kayak has to
rise on a wave exactly at the moment the radar antenna (rotating happily on
the radar mast) is pointed exactly at you.

Twenty years ago all ships carried radio officers who also maintained the
radar equipment (and, in fact, carried special endorsements on their FCC
licenses showing that they were qualified to do it). Radar sets are both
transmitters and receivers and those systems can be tuned for maximum power
output and sensitivity, respectively. The feedlines to the antennas from the
radar units also needed regular maintenance. Today, partly because of
satellite systems, ship operators no longer are required to carry radio
officers and so any maintenance of the systems gets done on an ad hoc basis
whenever the ship is in port. It's safe to say that, in general, virtually
no radar system on any civilian vessel is in top tune any more. The upside
is that because of advances in technology, the systems are not as sensitive
to being out of tune as they used to be. But it's still a factor; especially
on vessels with older radar units.

It should go without saying (but I'm going to say it anyway) that a kayak
has to reflect more microwaves back to the radar antenna than its
surroundings. This is a bigger challenge than you'd think. Even steel
50-foot sailboats do not paint a good target on a radar display when the sea
is full of whitecaps. Fiberglass, wood, or SOF kayaks are a good deal less
reflective than steel sailboats. Figure it out for yourself. Adding a radar
reflector is probably not a bad idea as long as it doesn't create an issue
with handling the kayak. But I think that adding a mast and reflector to a
boat that is paddled by hand with no keel and no ballast has to create some
issues; especially in the sorts of conditions in which you'd actually want a
ship to see you. I suppose I could be wrong about this, but I don't think
so.

And finally the part over which no one has any control. Like the tree
falling in the forest, even if the radar return of your kayak paints a
perfect blip on the radar display if there is no one sees it then it's not
going to do you any good. Once a ship is out of the harbor and on course at
sea there is usually only one person on duty and on watch on the bridge;
even on 900 foot tankers displacing over 50,000 tons this is generally the
case. The mate on watch has a bunch of duties and even though keeping a
visual watch is the most important of all of them, it still has to take its
place in the queue of things to do. The mate divides his time between
checking the ship's position, looking for traffic in all directions,
checking the course (usually set by autopilot) and speed, and checking the
radar.

Inside harbors there are many more people on the bridge (pilot, Captain,
mate on watch, and able seaman on watch (and usually on the wheel steering)
but there is much more to do and maybe even less time for anyone to actually
look for a kayak. After all, they're often under a vessel traffic system and
assuming that any traffic of consequence would be reported to them over the
radio. However, because these are often more protected waters, there is at
least a better chance of your kayak being painted on the radar display. That
display is likely to be the CAS (Collision Avoidance System) which gives
them an indication of where every target on the display is now in real time
and also a prediction of where they will be in 5 or 10 minutes (as selected
by the officer on watch).

Call me a cynic, but I don't worry about a radar reflector on my kayak (or
power boat). I carried a Davis radar reflector hard-mounted on the spreaders
of our cruising sailboat because it's the best possible reflector (still)
and affected sailing performance of the yacht not at all. It probably didn't
help much, but at least it didn't hurt. I cannot imagine any radar reflector
on a kayak that wouldn't create some sort of handling issue.

My advice is to keep a careful watch both ahead and astern using your eyes
and ears (both required by the rules of the road, by the way - which
basically means listening to your ipod is going to affect your liability in
the event of an incident), stay out of vessel transit lanes and off the
center lines of any ranges, and try to visualize where ships and boats are
going and either stay away from those places or be on high alert.

It's like the guy who broke his arm in two places; the doctor told him to
stay out of those places.

Craig Jungers
Moses Lake, WA
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