Radar Visibility for Kayaks

[scamlin]

Came across a useful article describing a series of tests on radar visibility for kayaks. Very thorough and good winter reading: enjoy.

http://www.seagrant.umaine.edu/documents/p...areffinal05.pdf

In an NSPN-CG informal test a few years ago at the Merrimack station, standard radar reflectors (the sphere you see on sailboat masts) were useless in the on-water test. So were a reflective emergency blanket, foil under the cap and crumpled foil in the hatch.

If I remember, the one device that sort of worked was a Watchdog reflector (#5 in the above article). It was a 2-3" tube about 20-24" long with a reflector element inside. It had a suction cup on the bottom for the deck of the kayak and a tether.

US Sailing and Safety at Sea did an older study in 1995 comparing signal returns for various devices. See http://www.ussailing.org/safety/Studies/ra...lector_test.htm

There is a high tech solution: radar SAR Transponders, but they are intended only after your in the water and the SAR is underway. See http://www.landfallnavigation.com/-ssart.html

Scott

[Brian Nystrom]

While the article is interesting, it's apparent from the photos that the test took place under ideal conditions, which would provide stronger, more consistent returns and minimal noise on the radar. The tests we did with the local CG were much more realistic, as they included bad weather and chop - conditions where a rescue is much more likely than on a sunny, calm day. The conclusion drawn by the local Coasties was that in rough water, kayaks were essentially invisible. One remarked that the return was similar to what he'd see from a gull or piece of flotsam and it was really difficult to separate anything from the noise. The tested radar reflectors did little or nothing to enhance the signal, though as Scott mentioned, the tall, tube reflector (long out of production) performed the best.

We did learn some things that were important in making ourselves easier to find in an emergency.

1- The CG has direction finding equipment that allows them to home in on a VHF radio signal. They cannot judge range, but it gives them an accurate bearing to your location. This is one more reason that paddlers should carry radios.

2- Aids to visibility are important. During the day, smoke signals are the most effective from a distance, followed by reflectors (if there's sun), flares and brightly colored boats/paddlers (white hulls don't help much in frothy water). At night, flares are key, but Cyalume sticks help and are quite visible from helicopters.

It seems that the bottom line is that a radar reflector should probably be one of the last things on one's shopping list of signaling gear, as other items are much more effective. Although I don't recall if we discussed them with the CG, EPIRBs and PLBs, are far more effective than pretty much any other device, but they're still rather expensive, especially considering the low risks of most of the paddling the typical paddler does.

[Guest _rick]

Regarding RDF.....The coast guard maintains RDF equipment on all boats as well as the station. Triangulation is often used to locate the offending fake distress calls..much to the dismay of the offender. RDF equipment is often used to triangulate a by dispatching a boat or utilizing another station.

While range and bearing are important, perhaps more telling is the application of auxiliary vessels/radio equipment and the use of the "high" side and "low side" to determine relative location.

The High side is a independent anntena system that the station and sector radio rooms control. It provides more range because it is , you guessed it, high on the antenna tower. All high sides can be linked together to provide wide area coverage if necessary.

Remember you sitting in a boat with 1 to up to 5watts of power have a very small effective line of sight range usually a few miles at best.

Soooo...in addition to unseen you may be very likely unheard too.

FWIW

[donperry]

It seems that the bottom line is that a radar reflector should probably be one of the last things on one's shopping list of signaling gear, as other items are much more effective. Although I don't recall if we discussed them with the CG, EPIRBs and PLBs, are far more effective than pretty much any other device, but they're still rather expensive, especially considering the low risks of most of the paddling the typical paddler does.

Tim Gutmann’s final experience last May prompted me to buy a PLB.

http://pressherald.mainetoday.com/news/loc...510kayaker.html

SAR could have had his position within a few minutes if he had one to trigger in his PFD. And the signal would have carried on long after he lost the ability to use a VHF. The latest model isn’t much larger than the M88 I have in the other pocket.

Anyone would gladly cough up the $650 for a PLB if they really needed it.

[JohnHuth]

I had a chance to play with radar reflectors about two years ago. I went to such outrageous lengths as inflating weather balloons to hoist up reflectors in the sky. I even tried to use a kite to hoist a radar reflector. Obviously this isn't terribly practical - but it was an interesting exercise.

In the tests, I found that, in moderately choppy conditions, there's almost nothing that you can do by way of having a reflector on board that works - it gets totally swamped by wave clutter.

The balloon/kite idea actually does work, but it's impractical.

I don't know about SAR - but if you're trying to make yourself visible in the fog, you'd have to turn it on.

So, I'm just in the conventional mode - flares, VHF, smoke, horn. If it's foggy, I'll do a securite' call when appropriate.

[Pintail]

If reflective material in (say) one's PFD is going to make any difference to one's visibility on the high seas, then I presume that that infers proximity to the source of radar and there is <one> aspect of all this that no one has mentioned -- and I am guessing that no one is even aware of this.

To wit: radar is not good for the human (animal) body. I once confronted the owner of a motor cruiser which was tied up at the dock at Cape Ann Marina: his radar scanner was running (although he <said> it was "on standby"). Any microwave radiation, in significant quantities, can harm the gonads and who knows what else...it should not be used deliberately close to other vessels. After landing an aircraft, one of the first tasks up front is to switch radar back to standby.

I shall continue to try to stay well-clear of any boat using radar near me and, as Brian Nystrom points out, all this talk is highly academic and we should attempt to be as self-sufficient as possible.

[EEL]

>, all this talk is highly academic and we should attempt to be as self-sufficient as possible.

Relying upon oneself is the first priority. My experience with radar involved aircraft and mortar shells as opposed to marine environment, but I have watched some small marine radar units and been amazed at how much clutter and junk was shown. I don't see how a kayak can be seen on the typical marine radar except at very close range and with an attentive operator willing to take the effort to see which returns that are moving. If you are in trouble and need to rely on someone finding you by radar, you are really in the position of finding out how flexible your spine is cause its bend over and kiss it good bye time. I know some of the folks that participated in the Maine study. I think it is fair to say they came away with a somewhat fatalistic view regarding avoiding being run down due to radar and an even greater belief in the critical importance of being responsible for your own safety. For example, when in fog, you stay close to shore and you announce crossing and then go as fast as you can to reduce the time at risk.

[Adam Bolonsky]

Tim Gutmann’s final experience last May prompted me to buy a PLB.

http://pressherald.mainetoday.com/news/loc...510kayaker.html

SAR could have had his position within a few minutes if he had one to trigger in his PFD. And the signal would have carried on long after he lost the ability to use a VHF. The latest model isn’t much larger than the M88 I have in the other pocket.

Anyone would gladly cough up the $650 for a PLB if they really needed it.

Also you can rent PLB's for about $45/week from plbrentals.com. They sent me a demo model to write about, review and photograph. I'll be putting up posts on it soon.

Very small and compact, all things considered. And registration is not only painless but free.

[Jed]

In an NSPN-CG informal test a few years ago at the Merrimack station, <snip>

That was a fun day. What ever happened to those idiots that went out as test dummies? ;-)

cheers,