Radar reflectors

[Jammer]

In another thread there was a summary posted of a collision at sea that occurred about 25 years ago. While there were many contributing factors, one of them was that the larger ship could not see the yacht on radar. This was before AIS, and before 25 years of technological progress in radar, and it involved a fiberglass yacht with a carbon fiber mast. One of the official findings in the accident report was that the collision could have been prevented had the yacht carried a radar reflector.


Do radar reflectors still make sense today?


Are they useful for sailing vessels that transmit AIS?


Is it necessary to hoist them aloft given that current radar technology is much better at discerning targets near the surface?


Do you carry one? Do you use it? How large?



Do cruising sailboats with aluminum masts have enough invisibility on radar today -- with the radars actually in use on today's commercial vessels -- that a reflector is necessary for them to be visible?

[Pete7]

Yes to all of those.

Pete

[Mike OReilly]

I recall reading a study of the effectiveness of various radar reflectors. Maybe done by Practical Sailor? Can’t recall for sure, but they’ve been studied.

From memory, I think the study found most reflectors used by recreational boaters were of limited use, although they found that some were better than others. I always figure they’re better than nothing, but maybe not much better.

I still carry two reflectors. A tube version is permanently mounted up on my aft stay. I also have a collapsable spherical version (Davis I think). I used to hoist it in low visibility times. Now that I have radar myself I’ve stopped doing so, but I still carry it as a backup.

[NewMoon]

IIRC, in that Practical Sailor test the simple spherical one was one of the better ones, certainly for the money, PROVIDED it is properly mounted, in the "catch rain" position.

I carried one on my 26 foot power cruiser, simply lashed down on the cabin roof, in the correct position.

Traveling Icy Strait in thick fog, we were hailed by a cruise ship four miles behind us, asking our intentions. I guess we showed up on the ship's radar.

[svHyLyte]

Mr. O'Reilly may be referring to the (click on) "Radar Reflector Test" of 1995. None of the reflectors, at the time, was too impressive although the inexpensive Davis units seemed to do pretty well. Although the Mobri units were "panned" when they were not upright, we have two of the 4" diameter units on our upper shrouds above our second spreaders on either side of the mast that angle inwards toward the masthead at about 15º-20º. The angles about correspond with our preferred maximum heeling angle so one or the other is near vertical when we're underway. I have, on a number of occasions, called passing ships on the vhf and given them our bearing from them to us and approximate range and inquired whether they could see us on their radars and have been assured they do including one ship that advised they had been watching us for "15 miles" and had guessed we were a sailboat as we were "slower than a herd of turtles" and had so adjusted their course slightly to pass a mile or so behind us at the CPA.

The best assurance of being seen would be an active radar target enhancer such as the "See Me" but at $1,400 USD, these puppies are not inexpensive and an AIS transponder might make more sense.

FWIW...

[IslandHopper]

Originally Posted by svHyLyte

The best assurance of being seen would be an active radar target enhancer such as the "See Me" but at $1,400 USD, these puppies are not inexpensive and an AIS transponder might make more sense.

FWIW...

Or the EchoMax, I fitted one and they are a brilliant piece of kit returning a large strong target, and as mentioned on the website they where a mandatory fit on all Golden Globe Around the World 2018 single handed race yachts.

https://www.echomax.co.uk/radar-targ...dual-band.html

[barnakiel]

We do not have any but I think we should.


b.

[hellosailor]

I also recall the PS review that HyLyte mentions, and how nothing really impressed them at the time. I always thought that some time with a band saw and some of the millions of AOL CD's that were shipping out in the mail could produce a great way to make radar reflectors and recycle CD's in one shot.(G)

The EchoMax looks nice, and the standby drain of only 23mA wouldn't bother many boats. But in an area where there is traffic, it will kick up into the 150-190mA transmit modes, and pull possibly 4-5 amps in a 24-hour period. Not intolerable--but better suited for boats like the Globe racers crossing big empty spaces. If they got the price down to $89.95, it would be a no-brainer to buy one.

[Uricanejack]

Local law requires me to have a radar reflect as part of basic minimum requirements. So I have one permenantly on my back stay.

Contrary to the op. Radar has not improved much since the 1950’s.
Most of the main technical tevelopments were in place. By the end of the 1950s gyro stabilization and true motion were available options. Both X and S band were avalable.

What has changed is how the radar information is displayed.

40 years ago. Radar displays were. cathode ray tubes. With valves capacitors and tubes. They were entirely manually operated and required darkened conditions to use. Ither a dark screen or hood.
Radar waves was created by a large magnetron on deck and sent by a precision made wave guide to a scanner on the mast.

The first big change or improvements.
In the late 70’s computers were added for Automatic Radar Plotting Aids or ARPA. Which became mandatory by the early 90s
This didn’t improve detection. It improved or made plotting easier.

By the end of the 80s. The old analogue CRT’s were being replaced by daylight screens. Which were computer screeds. The old image of the sweep is a placebos. The display is actually just a bunch of pixels created line by line. By the computer.
While This makes radar much easier to use during the day. It doesn’t improve detection.

Today a ship being fitted with a manually operated CRT radar with a plotting screen would be rare. Most will have the more modern daylight screens at least one of which will be a full ARPA the other might not be a full certification ARPA but probably has all the functionality of an ARPA.

They may be stand alone units with separate AIS or in some cases fully intergrated.

The new technology is all about the displays.

You might find this hard to believe. The radar not only isn’t any better. Many user might tell you. The modern radars are not nearly as good. Why?

Better technology often means cheeper, not higher quality. Which is only part of the answer.
Ditgital rather than analogue. Ditgital is stepped. Analogue is infinitely variable.
The number and sise of steps.
Mean settings are often not quite enough or just a bit to much.

The main difrence is manual setting by the operators is mostly replaced by. Initial set up by the installation and computer processing. With automatic functions.
Even the manual settings have limited variations.

All radars have the basic mandatory functions.
Brilliance is just a setting for day or night.
Gain variable .
Tunning is predominantly set at installation with only a minor ability to adjust. Often used as an automatic function.
Rain and Sea clutter are required. And work in the same way but ditgital stepped and often set to automatic rather than manual.

On top of this most manufactures have proprietary processes which can further process the picture eliminating returns based on algorithms on the number of times a return is detected.

The picture on the screen is ussualy highly processed.

End result.
The modern radar has a very clear apparently good picture. Which may have processed out small targets an experienced operator would have noticed on an older analogue radar.

Do Radar reflectors help. I believe they do. Some reports confirm they do, others suggest not very well.

AIS if the ship has it intergrated with the radar it will be very helpful. If it’s not intergrated. Not so much.

Most ship owners tend to fit the ship to minimum requirements only upgrading if required or when parts are no longer available.

Some will have the top of the line options.
A lot will have the minimum requirements.

I would advise at least one good basic reflector hoisted at all times.
Suplimented with a better active reflector or an AIS transponder if you like.
A good set of Nav lights. And keeping your own good lookout.

[Lepke]

On my commercial fishing boat, 55 feet, I had 2 of the foldable foil covered radar reflectors permanently mounted just below the crosstrees. Others told me the boat appeared on radar ship size.

[Benz]

I hedged my bets by mounting my Davis reflector at the masthead, where it can't be blanketed by anything. Every passing ship, as far as I can tell (they've all made way for me at sea) has seen us on Radar (no AIS on my boat). It may look a bit odd with a ball up there just under the Windex, but it sure helps to find it in a crowded parking lot.

[Spot]

How about a couple of these?
The picture is all in good fun...but seriously:

How much metal does it take for a good radar reflection?
Would one of those silver mylar balloons work ?

[SailRedemption]

There was a analysis of reflectors by Yachting Monthly in 2012.

https://www.yachtingmonthly.com/arch...ctor-work-2874

We have a Echomax 230 that will go above our radar mount above our first spreaders.

[NewMoon]

Originally Posted by Spot

How about a couple of these?
The picture is all in good fun...but seriously:

How much metal does it take for a good radar reflection?
Would one of those silver mylar balloons work ?

It's about the angles of the reflecting surfaces. That's why the simple Davis Echomaster ($40-$60) works well, IF mounted correctly. I wouldn't expect much from the balloons.