PaddleWise Discussion on Kayak Radars

Date: Wed, 20 Oct 1999 22:06:54 4
From: "skimmer"
Subject: [Paddlewise] Kayak Radar visibility

A group of us once paddled in heavy fog among islands on the coast of 
Maine.  A Coast Guard boat loomed up from the mist and suggested we 
stay out of the channel.  They said we were only barely detectable 
with their hotshot radar, and would likely be entirely undetectable 
by average marine radar systems on private yachts. We encountered 
this patrol in an area of dead flat calm water.  We were not 
"obscured by waves".   We were studying navigation at the time.

I recently received a request for information about making kayaks 
detectable on radar.  

I don't have a useful response.  On those occasions that we paddled 
in heavy fog (visibility 100 yards), we stayed in a tight group, 
listened for other boats, sounded horns upon hearing other boats, 
heard their horns in reply, and listened as they veared around us. We 
never saw them.  We stayed out of boating channels except to cross, 
and crossed rapidly when we heard no traffic.  We mostly avoided 
traffic in this way.

Can anyone provide  some useful advice or experience on making 
sea kayaks visible to radar when paddling in heavy fog ?

Chuck Sutherland

Date: Thu, 21 Oct 1999 09:54:20 EDT From: Subject: Re: [Paddlewise] Kayak Radar visibility Chuck Sutherland wrote, "A group of us once paddled in heavy fog among islands on the coast of Maine. A Coast Guard boat loomed up from the mist and suggested we stay out of the channel. They said we were only barely detectable with their hotshot radar, and would likely be entirely undetectable by average marine radar systems on private yachts. We encountered this patrol in an area of dead flat calm water." Chuck has asked about ideas on radar visibility for kayaks. We have bounced this subject around before on PW, and there was a pretty comprehensive article done in Sea Kayaker a while back --- don't have the date --- which, from memory, indicated that there were no viable means to enhance a kayak hull's radar cross-section, its radar visibility to an oncoming ship; however, there are commercial metal or metalized foam three dimensional radar reflectors available at boating supply stores (~$15-20) which, if mounted on a nominal four to six foot mast on the after deck of the kayak, will provide some enhanced passive visibility for a kayak. (All this assumes that an oncoming vessel operator is (1) looking at his scope, and (2) is seriously concerned about a very small blip on his screen --- the argument being that he may be far more concerned about a blip indicating the presence of something bigger and meaner than himself --- like Nova Scotia or something. But that's a different thread.) An option to this for deep-pocketed kayakers --- or maybe trip operators or instructors with insurance concerns --- is a Search and Rescue Transponder (SART). SARTs basically monitor radar frequencies and, when they are swept by a radar signal, answer back to that radar transmitter that there's something there. You will not resemble a Canadian province, but you will certainly indicate your presence to the oncoming vessel. Re the "deep pockets" issue: a SART is going to run between $1200 and $1500 (US). A cheaper option is one of the inflatable assistance widgets sited in Sea Kayaker in April 1998, the Sea Bouy (see This is a diver's device which inflates into a four foot international orange cylinder with retroreflective tape at the top and a radar reflective element in the top. Mounted to a kayak's rear deck, this widget could provide a quick inflating "mast" and some passive radar protection (said to provide a one mile indication in an independent boating magazine's test). The price tag on this guy is somewhere around $100 (from memory). Again, the oncoming vessel has to be looking and concerned --- both big assumptions. (And this doesn't even address the idea of recovering the kayak from a knock-down with a six foot mast or a four foot inflatable cylinder above your after deck! Other serious safety issues here.) Bottom line: I have used boat store radar reflectors in nighttime tests of search and rescue (SAR) equipment in open ocean scenarios in the past; mounted to a bouy at a nominal three foot height above water level in two to three foot seas, these things were marginally effective inside a one mile radius --- and we were definitely watching for them on the vessel's radar because they were attached to several thousand dollars worth of equipment which we wanted to recover at the end of the evening! My guess is that passive radar reflectors at heights above water which a kayak could conceivably provide would be, at best, marginal. Better than nothing? Sure. Good if the Coast Guard is out there actively searching for you? Definitely. Valuable to a kayaker skirting or crossing a channel in fog? Dunno --- wouldn't bet my life on it. Better bet? A SART for the instructor's boat, keeping the flotilla in close formation. Best bet? Stay out of the fog altogether. My somewhat more than two cents. Jack
Date: Thu, 21 Oct 1999 10:21:06 -0700 From: Subject: Re: [Paddlewise] Kayak Radar visibility Let's face it, you are duck soup in fog. You're best staying off the water in trafficked areas in fog, period. Even if this means adjusting your schedule to wait out the fog. If it descends on you while on open water, get to anything you can that is solid such as some rocks or a bouy and stay there til things clear even if it takes half a day. One of my scariest times ever on the water was on an Albany to NY Hudson River trip on the day at mid-point where we started off one early morning in such thick fog that we could hardly see 3 feet past our bow. Going down river, we constantly bumped into the shore on each side like a ball in a pinball machine, so blind were we. I kept expecting some cement barge and tug from the factories near Cementtown NY to run us down in this early morning fog. In hindsight, we should have stayed at our campsite, drank more coffee, worked on knot-tying etc. and waited for the thing to lift a bit. Forget about reflectors, etc.; they won't work for all the reasons stated by Jack, most particularly that they make such a some blip on a radar screen that only the most microscopic-eyed operator would spot it...most like it would be dismissed as a quark in the system. ralph diaz - -- - ----------------------------------------------------------------------- Ralph Diaz . . . Folding Kayaker newsletter PO Box 0754, New York, NY 10024 Tel: 212-724-5069; E-mail: "Where's your sea kayak?"----"It's in the bag." - -----------------------------------------------------------------------
Date: Fri, 22 Oct 1999 10:22:21 +0100 From: "Colin Calder" Subject: [Paddlewise] Kayak Radar visibility Jack Martin wrote some interesting stuff about radar reflectors. There have been a series of articles on the subject recently in Practical Boat Owner magazine. During the course of the articles a number of commercial passive reflectors were tested on a sailing yacht for radar visibility from a large commercial power vessel - the conclusions as far as I recall were that these passive reflectors at best made virtually no improvement to the radar reflection of the yacht, and in several cases actually reduced the reflection. This caused some consternation, and the reflectors were taken to a military radar test facility, where it was found that in certain circumstances they could cause interference which cancelled radar reflections from the yacht itself! I would guess that if a reflector up a 50ft mast doesn't help, its not going to do much on a kayak/paddler which is completely (at least from sea level) obscured when sitting in the trough of waves bigger than say 3-4 ft. Stealth kayak! - I would assume that you are invisible to the eyes and radar (if anyone is actually looking at it) of other craft. I personally don't have much concern about being run down by commercial vessels (kayaks are pretty much the only craft which tend/are capable of nosing around/in the local sea cliffs where I do maybe 90% of my paddling). However, I wonder whether some sort of active transponder would give kayaks a noticeable radar signature. As a research student I spent some time at a wildlife field station radio tracking deer. At this time (~1990) active radar transponders were being tested for wildlife telemetry/tracking. Units were fitted to pink footed geese. Geese obviously swan (sic) around somewhat higher above the water than kayaks (at least those which aren't equipped by inflatable crotch dirigibles) but as far as I remember you could follow geese fitted with transponders around quite effectively (at least when they were airborne) over the range of a standard marine radar outfit. GPS/satellite transponders came on the scene about the same time for wildlife telemetry and I haven't heard anything more about the use of radar, but the units were obviously relatively small and light if they could be carried by birds (I assume <5% of the body weight of a goose)- presumably because most of the weight would be the battery, which can be relatively small because the unit only transmits when it receives incoming radar. This may have already been tried on kayaks/boats, I don't know, but food for thought. Cheers Colin Calder 5719'N 210'W
Date: Fri, 22 Oct 1999 07:45:11 -0700 From: Dan Hagen Subject: Re: [Paddlewise] Kayak Radar visibility Pains Wessex makes a relatively compact marine radar transponder: However it is very expensive, and while relatively compact, it is still a bit larger than is desirable for use on a kayak. Given this, and given that I paddle mainly in areas where larger boats fear to tread, I have not been tempted to buy one. But if I paddled in New York I might be tempted, given some of Ralph's stories of heavy ship traffic (and mystery barges) rumbling about in the fog. Dan Hagen
Date: Fri, 22 Oct 1999 09:24:17 PDT From: "Philip Torrens" Subject: Re: [Paddlewise] Kayak Radar visibility The unit itself looks relatively compact, but the reference to leads strongly suggests it is not self-contained, but runs off your 12-volt marine battery (as found in every kayak:-) . I'd be worried about running down my battery and not having enough juice for the Rule 500 pump and the drinks blender... Philip Torrens N4916' W12306'
Date: Fri, 22 Oct 1999 12:25:25 -0800 From: "Rev. Bob Carter" Subject: [Paddlewise] radar An important point about being visible on radar. Even if a ship has "the best radar" and your kayak is made entirely of radar reflecting material the main safety factor is whether or not the ship's crew is paying attention to the radar. Obviously the crew of the Exxon Valdez was not! Bligh reef was marked and visilble on radar. Last summer here in southeast alaska the ferry LeConte (200') almost collided in the fog with a small cruise ship. Both ships had radar! They missed by 50'! Also I have often seen fishermen in southeast working the back of the boat where the fishing gear is and they only occasionally look forward to see if they are still on course. The radar could be showing a dozen kayaks and they would not notice. Also some of the bigger ships in narrow passages have little or no room to manuvover and it takes miles for them to stop! So I always assume they are unaware of my presence and it is up to me to stay out of their way. Happy boating Bob sitka
Date: Fri, 22 Oct 1999 14:44:15 -0700 From: Jerry Hawkins Subject: Re: [Paddlewise] radar Regarding radar (again), It isn't the really huge ships one should worry about, in that (as all agree) there is zero possibility of making them see you, and frankly they won't stop or maneuver around you anyway. Stay out of their way. It isn't hard to stay out of the main shipping lanes in most areas. It is the medium and small guys that behave erratically. Those people may have their radar turned off, even in fog, or have no experience or training. For the 30' fishing boats and cabin cruisers and sailboats, you just might be visible on radar, under best of circumstances, but this will never be reliable. Whether you are canoeing, kayaking, or even in a small to medium motorboat, the best advice is to assume they don't see you, don't have radar, and may have been drinking. There was a major collision in the English Channel in August -- two experienced captains, large commercial boats, radar, GPS, and damn if they didn't hit each other anyhow. A freighter out of San Francisco hit a large fishing boat called the Jack Junior a few years back, caught its nets, dragged it underwater, and no trace was found for months. You just have to minimize time spent in the shipping lanes, know you are invisible, and work from there. jerry.