Where is your radar reflector?

[PaulK]

I've never heard that the radar reflector needs to stay vertical to be effective....

Everyone says to make sure the Davis Echomaster is mounted in the "catch rain" position to provide the best returns. The reports on the Plastimo tubular radar reflector seem to show that it ONLY works when it is at a specific angle to the sending radar signal. Maintaining that angle on a sailboat under way without necessarily knowing where the signal was coming from would seem a fool's errand and a waste of any money spent to buy it.

 

[chuckwayne]

Everyone says to make sure the Davis Echomaster is mounted in the "catch rain" position to provide the best returns. The reports on the Plastimo tubular radar reflector seem to show that it ONLY works when it is at a specific angle to the sending radar signal. Maintaining that angle on a sailboat under way without necessarily knowing where the signal was coming from would seem a fool's errand and a waste of any money spent to buy it.

my dealer recommended the plastimo when I bought Escape, one on each upper stay. When we actually looked at the reflection on other radars, we realized the things were useless! replaced with the trilens and it made a huge difference in the radar image seen by other boats. Highly recommended (used by the Navy on subs) and not sensitive to heel angle. the small version fits perfectly on a sailboat mast

 

[MikeHoncho]

I have two of the smaller tubular ones on the underside of the spreader on the cap stays

 

[FastOlson]

I have two of the smaller tubular ones on the underside of the spreader on the cap stays

Your solution sounds good to me. I have one of the tubular ones on an inside shroud just above the lower spreader. A friend has a similar one on each side of his rig.

I would caution against viewing these measures as "yes or no" answers. There was a real world test by one of the magazines many years ago with measured radar returns and distances specified for all of the major technologies. Their best/recomendation was for the full size Davis model in the correct "catch rain" position, and a very expensive Firdel Blipper (sp) was slightly better albeit with cost and mounting concerns. The tubular ones tested were not quite as good as the Davis.

I used a Davis reflector on our backstay, on our prior boat for a decade. It would rotate slightly back-n-forth in a breeze and did somewhat concern me about possible stress on the swages over the years. No problems, but it was a tad worrisome.

The tubular ones come in two sizes AFAIK, and we chose the smaller diameter version.
The biggest takeaway from that real-world testing was that Anything... is better than no reflector at all. That's because a fiberglass sailboat hull with a rounded spar is terrible at returning a reliable radar signature. We know this from observation, also.
If you have a believer in alien abductions crewing for you, do allow him to wear his crumpled tin foil hat!

So, be seen and be safe........

 

[PaulK]

US Sailing tested various reflectors in 1995. https://www.ussailing.org/wp-content/uploads/2018/03/radar-reflector-tests.pdf
They found that the cylindrical type ..."With the radar beam exactly at right angles, they act as a series of dihedral reflectors, but even small heel angles cause it to operate in a deep null with little reflection. The series of end plates that would form the third side of each trihedral are too small to be effective, even in X-band, and are operating too close to edge-on at small heel angles. The smaller 2" diameter unit suffers an additional problem in that the 1" radius of each dihedral reflector is less than a wavelength even at X-band. Both Mobri reflectors have provision for hanging the cylinder from top and bottom, or can be strapped to a wire or spar. The manufacturer suggests mounting one on each cap shroud above the spreaders, which would provide a reflection at two narrow angles of heel, rather than just one."

Having a reflector that only works when it is at 90º to the radar beam, even if it is aerodynamic and easy to install, is like having an inflatable life vest with an empty CO2 cartridge. It might look like you're well equipped, but you're not.

 

[MikeHoncho]

Never say never but I tend to motor slowly with no sails up ( that one is a always) when in conditions I’m depending on my radar, and in doing so, depending on a reflective signature. Like I said l, never say never but in the Puget sound with all of the traffic, variable wind and close proximity shores, I’m not sailing in the fog. I’m going to have my radar and VIS fired up and watched closely.

 

[joker460]

There was a 2007 test report as well. https://www.westmarine.com/on/deman...Images/legacy-pdf/Radar-Reflectors-Report.pdf

 

[PaulK]

There was a 2007 test report as well. https://www.westmarine.com/on/deman...Images/legacy-pdf/Radar-Reflectors-Report.pdf

...and it says essentially the same thing. Unless the cylindrical reflectors are exactly at the right angle to the radar beam (and who knows what that angle is, since it's foggy and you can't tell where the sending unit is), the return falls off to almost nothing. Note that the tests are done in a lab, with the sending radar and reflector both fixed. With the cargo ship's radar and your sailboat both moving, a cylindrical reflector might never be at exactly the right angle to generate a return.