Where is your radar reflector?

[CarlN]

While neither is a substitute for the other, I consider the benefit of AIS to be more as an additional radar reflector than an additional radar. Like it or not, AIS is the now the primary anti-collision technology on commercial vessels over 65ft. Even with a radar reflector, the weak radar return from a fiberglass sailboat -- especially when healed -- can be overlooked. AIS never looks like a wave.

I still carry a radar reflector (mostly from habit and because they are cheap) but this British report analyzing radar reflectors after a sailboat with a reflector was run down by a British ferry causing the loss of all hands is not encouraging. The only one they really like was a the SeeMe active reflector that bounces signals back. The Davis did particularly badly even in "catch rain" position. A scary read.
https://www.gov.uk/maib-reports/sin...ff-isle-of-wight-england-with-loss-of-3-lives

 

[Jackdaw]

While neither is a substitute for the other, I consider the benefit of AIS to be more as an additional radar reflector than an additional radar. Like it or not, AIS is the now the primary anti-collision technology on commercial vessels over 65ft. Even with a radar reflector, the weak radar return from a fiberglass sailboat -- especially when healed -- can be overlooked. AIS never looks like a wave.

I still carry a radar reflector (mostly from habit and because they are cheap) but this British report analyzing radar reflectors after a sailboat with a reflector was run down by a British ferry causing the loss of all hands is not encouraging. The only one they really like was a the SeeMe active reflector that bounces signals back. The Davis did particularly badly even in "catch rain" position. A scary read.
https://www.gov.uk/maib-reports/sin...ff-isle-of-wight-england-with-loss-of-3-lives

The MAIB creates great reports. I try and read every one they create. One correction, there is no way of knowing if the yacht had their reflector up. It was never found. In any case, it did not show up on the ships RADAR.

The associated report on passive RADAR reflectors was damming. None worked well in real world conditions. Based on the French Class 40s collective love of the Plastimo Tube defectors, we mounted two on the upper diagonals of Kestrel’s rig. After reading that some time back, it seems the only real way to be seen is active reflectors, AIS, or eyeballs.

 

[chuckwayne]

Ditto! my Hunter dealer installed two of the plastimos on Escape on delivery, and they were useless! the trilens works decently based on our testing, but we also tested a friends SeeMe and it worked really well

 

[LeslieTroyer]

Mine is an old Davis already assembled in the lazerette readyto hoist in fog or dark.

Mahalo

 

[jssailem]

I have a Davis. It is on the back stay about 15 feet above the deck. Only issue is when in a storm the wind causes you the stay to vibrate.

 

[Gunni]

The Davis Echomaster manual details specifically how to rig the device with blocks and and a tether to the lower shroud. Mine has been installed year-round at the first spreader for more than 5 years, through gales and summer sun.

 

[pateco]

The Davis Echomaster manual details specifically how to rig the device with blocks and and a tether to the lower shroud. Mine has been installed year-round at the first spreader for more than 5 years, through gales and summer sun.

Their installation manual has a lot of details on how they work and suggestions on installation.

Echomaster Users Guide

 

[LeslieTroyer]

Given the sail shadow, I’m wondering if I should mount it to the top of my radar (on pole at stern) , or put on the back stay like John (@jssailem)

 

[Kings Gambit]

Yeah; it says to suspend it from the highest point possible, as from a spreader, and try to keep it from spinning. That's what I do, and what most folks I see who have one also do. (See Post #35.) However, most boats I see do not have one at all. We don't get a lot of fog here. Few boats go out at night here. We do not have long channels congested with shipping, etc. If you are not in the traffic lanes established for container ships you will most likely not get hit by one. Th real danger here is getting mowed down in the fog by an idiot in a powerboat going 25 kt and who likely cannot read his instruments anyway if even if looking at them. Add to that, the Davis Echomaster is not rated as highly effective to begin with (Post #61 "The Davis Echomaster performed least well out of the octahedrals, it had a peak RCS of 7.5m sq, but its average RCS and stated performance levels were only 2m sq and 0.45m sq respectively."). You might have a slightly improved chance of being detected in fog with a fog horn sounding off every two minutes in addition to the RF. How many folks have a fog hailer aboard? I'd guess there are more now with AIS than hailers.

 

[jssailem]

Here is an idea.
If the AIS system, Fog Horn hailer, Bell, Infrared Cameras, and Octahedral reflectors are not enough you could always...

Buy a set of Aluminized mylar film sails. It is a highly reflective, lightweight material that could be used to make sails for spacecraft driven by the light of the sun.

Or a radar system that pinged the radar system of any boat out on the foggy water, announcing your presences... But that would be like a military jammer and bring on a whole new set of issues....​

 

[py26129]

The Davis Echomaster manual details specifically how to rig the device with blocks and and a tether to the lower shroud. Mine has been installed year-round at the first spreader for more than 5 years, through gales and summer sun.

Ditto. Cheap insurance and pretty much trouble free except for the time a bird tried to nest in it

 

[Gunni]

Unless you are a radar tech or an electrical engineer that Brit report is of little use. Here are some key take aways : 2 square meters of radar reflection is about 2 square meters more than your boat reflects without a reflector. 2 square meters of radar reflection is plenty within 2 miles or so of distance. The higher the better. Your sails will attenuate your reflection.

We went out a few years ago and rigged my reflector on another boat. I wanted to confirm some of those items listed above. We then both sailed various distances from that boat with the reflector hoisted to the 1st spreader and not hoisted. With my multi-frequency Navico radar it was remarkable how a boat went from having no reliable return to having a steady radar return with the Echomaster when within 2 miles. On opposing tacks with the reflector behind the sail the detectible distance dropped, maybe in half. When the target was not moving, had no sails up and the reflector rigged it was consistently detectible to about 3 miles.

 

[Kings Gambit]

I imagine your radar was optimized for the task; you knew the target image and probably where the target would lie on the radar screen (i.e., where to look for it.) Not that it would not have appeared and been noticed otherwise.

 

[jssailem]

Optimized for the task or not, going out on the water in daylight and having known targets that you are trying to see on radar is an excellent way of learning to understand the signals your radar screen is using. You need to be able to decode the image.
I see more screens like this:

on local boats then the brand new digital images:

where the radar is superimposed on a graphic map.
Both function but you need to be able to interpret the information if it is to be useful.

Only way I know is to go out on a clear sunny day with unlimited visibility and play with your radar. And that goes for units like both of the above images.

 

[Gunni]

where the radar is superimposed on a graphic map.

John, yes, I have both the traditional radar only and the chart superimposed capability. That first image looks like the "bang" view of older radars. Not much of that on the multi-frequency newer radars.

Couldn't agree with you more about using and training on radar before you need it on a dark and stormy night! I was never trained on radar, always had "a radar guy" who by the way was AWESOME! Now it is on me and after many many hours of viewing and fiddling with settings I am finally proficient on my radar. what a great tool.

 

[Johann]

Or a radar system that pinged the radar system of any boat out on the foggy water, announcing your presences... But that would be like a military jammer and bring on a whole new set of issues....​

That’s what the Echomax Active reflector does. This one is X and S band:

https://www.defender.com/product.jsp?path=-1|135|2290117|2290118&id=2025506

Very effective according to the UK test report... but pricey!

 

[FastOlson]

I would hope that comments about the reflectivity of commercial reflectors do not dissuade anyone from using one. This reasoning harks back to the old saw about "perfection is the enemy of the good". When it's foggy it's way better to have something up there than it is to have nothing at all.

And, so true that an FRP sailboat has a very (!) poor radar return. I have tested this out in the real world and we found that simply bringing up (from below) an assembled Davis-type reflector and laying in on a cockpit seat made another sailboat about a quarter mile from me immediately show up on my screen, when he was not previously producing a return.

AIS invokes another scary assumption. Unlike radar, which shows you stark reality, AIS displays information that is calculated to be true, but also depends on myriad amounts of digital transmission and mathematical manipulation to display info attached to an icon. Wonderful as it can be, it's just another navigation 'tool' to help you assess traffic in your vicinity.

Lower down the technology scale would be the method used by Alaska fishermen a hundred years ago: his dog would stand at the bow and bark.... if the fisherman heard an echo he would immediately turn his boat away from the invisible cliff that was out there in the fog...

As the sergeant used to say they left the squad room: "Be careful out there!"

 

[Richard19068]

Interesting true anecdote about reflectors working. Friends of mine were off Venezuela in a 45' sailboat and were being followed turn for turn one night by what they considered a suspicious boat a few miles away. They had lights off and were getting a bit nervous about what to do until they thought about taking down their radar reflector. They said that after taking it down and making another turn they lost the following boat.

I believe it was a Davis Echomaster.

 

[py26129]

We often go up or down the Seaway, at night, where one shares a fairly narrow channel with 730' ships. While we can see them on AIS, we do not carry a transceiver. We do stick to the edge of the channel and always have our Davis Echomaster deployed and it is always a good feeling then the searchlight on the ship comes on to light us up for a second. I don't even mind the momentary loss of night vision.

Matt

 

[sailcrazy1]

I've never heard that the radar reflector needs to stay vertical to be effective....maybe I need to remount ours on the bottom of my Questus radar mount? Besides the radar and the radar reflector, and AIS, we also use an older system called C.A.R.D., Collision Avoidance Radar Detector, made by Survival Safety Engineering. When it receives a S or X band radar pulse, it gives a graphic (360*around the boat) and aural alert. Playing with the sensitivity control, you can get an idea of the distance...and then tune the ship's radar to search for the target. Where we've sailed for the last 15+years, the Medd and the Caribb, fog has not been such an issue. But a night-time sail in shipping lanes-good wx or not-can sure get your attention.