Attaching Radar Reflector

jssailem · Jul 10, 2019

6ft Step ladder in the cockpit.
Take mast down and attach while standing on solid ground.

Two workable ideas. Might want a helper holding the step ladder in place. More people fall from a step ladder then we know.

Parsons · Jul 10, 2019

Find out what your local yard charges for a guy on a crane. I was planning to swing out to the end of my spreaders to attach a couple of those cylinder reflectors, when the guy who was going to haul me up said that the local yard would send a guy up the crane for about $50. I didn't bother going!

Ron20324 · Jul 10, 2019

With a split backstay, you ought to be able to get an extension ladder from the cockit to the split then attach the RD above the split somewhat.

tfox2069 · Jul 10, 2019

So I've had my H36 for a year now, and have been learning the radar lately. Given this thread, I thought you might find a recent experience interesting. I've been running my Garmin GMR 18 HD radar during the daylight to both learn its functions, and to see what things look like on radar when I can actually see them during the day (so I can understand what I'm looking at on the radar in periods of reduced visibility).

Two weeks ago, in broad daylight, I had a Catalina 38 motor past me with its Davis radar reflector up above its spreaders, in plain unobstructed view of my radar. You can see the boat, less than 1/4 mile away, on my port bow as the yellow blob. By contrast, you can see a buoy with its own reflectors (admittedly more than the Davis) in the upper left of the photo. When I zoomed out I was surprised to find that other boats painted a very similar profile to the Catalina with the Davis reflector, essentially indicating no significant difference with or without the reflector.

Not scientific, just an anecdote at this point, but I'll continue to watch with interest.

Parsons · Jul 10, 2019

I'm not a radar expert, but there are some on this board so let's see what they say. From my limited understanding, however, radar has a sweet spot that is BETWEEN two ranges. Everyone thinks about the outer range (picking a return out a five or ten miles), but forget that close-in objects also disappear. At only a quarter mile, I wonder if you were too close to that C38 to get a good paint, but may have had better imaging at one mile.

tfox2069 · Jul 10, 2019

Parsons said:
I'm not a radar expert, but there are some on this board so let's see what they say. From my limited understanding, however, radar has a sweet spot that is BETWEEN two ranges. Everyone thinks about the outer range (picking a return out a five or ten miles), but forget that close-in objects also disappear. At only a quarter mile, I wonder if you were too close to that C38 to get a good paint, but may have had better imaging at one mile.

Fair point Parsons. I don't have any idea if the Davis (or any other) reflector paints more prominently at an "ideal" range", but I can say that the Catalina 36 didn't stand out in any way in terms of painting bigger as compared to other boats even out to ~3/4 of a mile. I also couldn't confirm or not confirm if the other boats around had reflectors up, but they appear to be comparatively rare in my part of the Chesapeake - which is one reason why I noticed the Catalina 36 and why I snapped the radar photo.

If I see one again I'll try to snap some photos at varying ranges and see if they make a difference. You've piqued my interest in this now. I would point out that Practical Sailor has generally panned passive radar reflectors, noting that unless its powered the return will be very modest, and is likely to be partially obstructed by rigging.

jssailem · Jul 10, 2019

Note. Rigging, mast, angle from target, type of reflection, gain setting, type of radar, boat design, boat materials, all of these have an impact on the display of a target.

I doubt that you can distinguish the rigging from a Davis reflector. You need to continually practice in daylight and clear air to begin to get a understanding of what is reflecting to your display.

I turn on my system and sit in the marina. Try to differentiate the reflected blips. Most time it is a lot of "Clutter".
I can see the islands and the open paths of water. That is where I would head in the event I was moving in a fog. As I get closer to the marina, there is a lot of confusion I believe generated by bouncing off my signal against the navy ships. Sometimes I think the ship guys are screwing with my signal. They are a big wall of green.

But you turn your view and you can see open water up the river.

It is a practiced learning task. A Catalina 38 looks pretty much like a 28 foot fishing boat and a 33 ft Cal sailboat. I try to avoid hitting the green blobs on my radar.

dlochner · Jul 10, 2019

The British seem to be very concerned about radar reflectors and their efficiency. A quick search found 2 interesting articles. I've only skimmed them.

https://www.ussailing.org/wp-content/uploads/2018/03/2007-Radar-Reflector-Test.pdf

https://keyassets.timeincuk.net/ins...20/filebank/reflector_performance_ym_june.pdf

dLj · Jul 10, 2019

I was told years ago that the best radar reflector on a sail boat was a one gallon jug of water hoisted up in the rigging. I have no idea if there is truth to that or not. Maybe someone here that has radar and have someone do this and find out how well it works... Just a thought...

dj

shemandr · Jul 10, 2019

tfox2069 said:
...Two weeks ago, in broad daylight, I had a Catalina 38 motor past me with its Davis radar reflector up above its spreaders, in plain unobstructed view of my radar. You can see the boat, less than 1/4 mile away, on my port bow as the yellow blob. By contrast, you can see a buoy with its own reflectors (admittedly more than the Davis) in the upper left of the photo. When I zoomed out I was surprised to find that other boats painted a very similar profile to the Catalina with the Davis reflector, essentially indicating no significant difference with or without the reflector...
View attachment 167017

But in the screen shot you can see the Catalina 38 with the Davis reflector and not the other boats you found on zooming. It seems to me that the Davis reflector WAS effective in lighting up your radar on the 1/2 nm zoom level and the other boats weren't - No?

shemandr · Jul 10, 2019

dlochner said:
The British seem to be very concerned about radar reflectors and their efficiency. /QUOTE]
Probably because they sail in bad weather a lot. I'm reading Ellen MacArthur's tome Taking On the World and in her circumnavigation of Great Britain there was a lot of fog. And when it wasn't foggy it was raining. Visibility was usually poor.

FastOlson · Jul 10, 2019

We installed a "tubular" reflector many years ago, on a shroud just above a spreader end. Wired on, and I recently was hoisted up on a chair to inspect it.
According to tests published in magazines, this is not quite as good as a spherical one deployed in the correct "catch rain" orientation on the backstay. However.... any reflector at all is mega-better than nothing. (!)
We use our radar in foggy conditions and it's interesting how many other boats -- small and not-so-small -- do not return a consistent echo.
IMHO, another case of not allowing theoretical perfection to get in the way of doing some good.
Picture of a similar one attached.

tfox2069 · Jul 10, 2019

shemandr said:
But in the screen shot you can see the Catalina 38 with the Davis reflector and not the other boats you found on zooming. It seems to me that the Davis reflector WAS effective in lighting up your radar on the 1/2 nm zoom level and the other boats weren't - No?

There were no other boats within the range that I had zoomed into. Just the Catalina.

tfox2069 · Jul 10, 2019

FastOlson said:
We installed a "tubular" reflector many years ago, on a shroud just above a spreader end. Wired on, and I recently was hoisted up on a chair to inspect it.
According to tests published in magazines, this is not quite as good as a spherical one deployed in the correct "catch rain" orientation on the backstay. However.... any reflector at all is mega-better than nothing. (!)
We use our radar in foggy conditions and it's interesting how many other boats -- small and not-so-small -- do not return a consistent echo.
IMHO, another case of not allowing theoretical perfection to get in the way of doing some good.
Picture of a similar one attached.

I would say that you cannot assume hoisting a Radar reflector is “mega better” than not hoisting one. Have a friend with radar show you what you really look like.

John Nantz · Jul 10, 2019

Read this thread earlier today but didn't have time to reply; however, here it goes:
What FastOlson (#14) said about the "rain catch" position is important. Look at the technical specs and the Davis works best in the rain catch position. If the Catalina in the radar picture didn't have their's installed in the optimum position it won't be reflecting as well as it could.

We've got our Davis on the split backstay and I had to use U-bolts to get it like that. One good thing about the split backstay where the reflector is mounted shortly above the split is the single cable from the masthead doesn't turn so the reflector stays in the position where it was mounted.

With regard to Headsail's installation question, since he has the boat in or near Tacoma, our area has some good tide swings (just finished the max swing for the summer), so a suggestion would be to go find a dock somewhere, set the boat up alongside, go up on the dock and do the installation. Might have to do some wiggling with the stern to reach the stay but that should be high enough.

Another thing to keep in mind is the radar return signal doesn't work as well on things that are wet, such as wet sails, so if the reflector is on the opposite side of the sail then the return signal will be degraded or not present.

Wood, and especially wet wood, is not a good reflector. Just south of the Narrows Bridge (Tacoma) are a couple mooring buoys to the side of the main channel. There is a rock quarry on the shore and they moor their wood barges on. the moorings. Years ago I was motoring in pea-soup fog on that side and had a big surprise. These barges are probably a hundred or so feet long and appeared to be made out of timber akin to railroad ties but of course longer. Don't know if they're still used there 'cuz it's been a while but it was a shock (to see it, not run into it).

Running in pea soup I've thought it would be good to have one-each of those tubular-type reflectors on the port and starboard stays to complement the Davis. Just haven't done it yet. We also have the Standard Horizon automatic fog horn setup but would like to connect a high-powered air horn to the system as the existing doesn't meet the Col Regs for db. More hurdles to overcome.

FastOlson · Jul 10, 2019

tfox2069 said:
I would say that you cannot assume hoisting a Radar reflector is “mega better” than not hoisting one. Have a friend with radar show you what you really look like.

OK... Hokey.... ! Well, the phrase had a nice ring to it when I typed it!

Whole idea is that a boat is much more likely to be visible with "some" kind of reflector. From my own experience, many decades ago, when we were trying out the green-screen radar that our '88 boat came with, I radio'd a friend of mine who was on a parallel course about 200 yards away to bing up his Davis reflector from below deck. At that point no matter how I adjusted the gain his 33' boat would not show up.
Soon as he brought that reflector up into the cockpit, he showed up immediately as a strong return on our screen. That was an early Apelco LCD radar -- quite the technology for that time! So, I do believe that some sort of enhanced reflectivity beats nothing.
Also, from being in thick fog in the Straits of Juan De Fuca for many hours in 2014, it was odd how many aluminum fishing boats would appear out of the fog, visually, that were not on screen (or were so intermittent that it was hard to ID them as a firm target. And that's with our present Lowrance digital radar unit, and it works very well on 'bout anything that can reflect at all.

dlochner · Jul 11, 2019

The recommendations from the report on the US Sailing website:

· Based on the results of this report it is recommended that yachtsmen always fit a radar reflector that offers the largest RCS practicable for their vessel.

· The RCS of the radar reflector should have a minimum consistent RCS of 2m2.

· The Sea-Me is the recommended product if power is available

· If power is not available then the passive Large Tri-Lens reflector is recommended

· The 4” tube reflector is not considered suitable due to its poor performance. It is also recommended that the 2” tube reflector is not suitable since the performance of this target will be even lower.

· It is recommended that poorly performing radar reflectors are not fitted as it is possible that the user could be lulled into a false sense of security believing that their chances of detection has been enhanced.

I believe the last recommendation is the most important one.

This article was in Panbo a few years ago. The Echomax 230i is an interesting design. It is inflatable, is easy to store, and weighs less than other similar designs. https://www.panbo.com/the-passive-radar-reflector-solution-for-sailboats/

tfox2069 · Jul 11, 2019

dlochner said:
The recommendations from the report on the US Sailing website:

I believe the last recommendation is the most important one.

This article was in Panbo a few years ago. The Echomax 230i is an interesting design. It is inflatable, is easy to store, and weighs less than other similar designs. https://www.panbo.com/the-passive-radar-reflector-solution-for-sailboats/

Very interesting position taken by US Sailing on being "lulled into a false sense of security". I work with data for a living, so I'm usually pretty skeptical until I see what the data says. I own a Davis reflector, and I'm hoping to get a friend to turn on his radar for me and see what I look like with the reflector hoisted in various positions, from various bearings and ranges. I have modest expectations, but hope to get some repeatable results which will work for my boat. Like everyone else who owns a radar reflector, our hope is that it provides some greater level of reflectivity. I just want to KNOW what I'm getting, rather than hoping.

Attaching Radar Reflector

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