11 radar reflectors tested : Not all models are really easy to see

Alexander Worms

 ·  14.05.2023

Radar reflectors in the test: A large reflector, suspended almost in the rain catcher position, produces a good echo

This is how we tested

11 radar reflectors in the test: the results, how radar reflectors work, radar technology: broadband or magnetron radar.

Who needs a passive radar reflector in the age of AIS? Thanks to modern electronics, you are highly visible on the screens, certainly on those of commercial shipping. Well, the question seems justified at first glance. On closer inspection, however, the answer is clear: everyone who is on the water with commercial shipping needs such a device. This is because AIS technology is dependent on a power supply - if this fails, the yacht is no longer visible. Passive radar reflectors work at all times. What's more, there are some areas, such as the Waddenzee in the Netherlands, where a radar reflector is simply mandatory.

Not much has changed in terms of products in recent years. On the market, the Tin cube which Tubes and the Echomax . There was also a device called Trilens. This reflector is now sold under the name 3Lenzz offered again.

But how good is the performance of the reflectors in practice and when it is not a question of being seen by large devices on the bridge of a commercial vessel, but by a less powerful yacht radar? First of all, it is difficult to make generalisations and the conclusions must be formulated precisely.

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yacht radar reflector test

The problem is explained using an example: the 3Lenzz consists of three spheres that are mounted at an angle of 120 degrees to each other. A test by the British coastguard had already shown that it has a blind spot every 120 degrees. If radar signals hit this blind spot, the echo on the screen disappears. All reflectors have such blind spots, to a greater or lesser extent. During our test, we recognised the 3Lenzz by the fact that the echo was clearly visible, disappeared for a few orbits and then reappeared. The test boat was obviously close to a blind spot on the reflector. In practice, this would be the case when approaching with an exact bearing, for example when a ship is travelling towards an anchor berth that is not swinging. However, if the angle between the two changes by just a few degrees, there is an echo.

The conclusion that it doesn't work well because it was sometimes poorly visible in the test would not be the whole truth. The echoes were clear when measured from a different position. The conclusion is therefore that the 3Lenzz delivers good results with changing courses of approach and only shows weaknesses at three points on the full circle.

To simulate the situation on a sailing boat, we measured each reflector vertically and at an angle of 30 degrees. Here, too, some models showed weaknesses. In particular, the models with an already small reflective surface sometimes collapsed significantly. However, even the weakest reflector ensured that our test pontoon appeared on the radar screen.

The echo of each reflector was measured a total of eight times - from a distance of 0.5 and 1.5 nautical miles, vertically and at an angle of 30 degrees, using a modern broadband radar and a conventional magnetron radar. The displays of the broadband radars are shown in the individual test images. Measurements were taken from a motorboat on which both antennas were installed. The reflectors were installed at a height of around three metres on a pontoon on a wooden mast, which could also be tilted. The results were then saved using a screenshot on the Garmin devices used; these were radars commonly used on yachts. We optimised the settings of the radar unit for the medium-sized sheet metal reflector and did not change them in the further course of the test in order to ensure the same conditions for all reflectors. We only tested the two inflatable reflectors in an upright position, as these are usually suspended.

Plastimo sheet metal small

Plastimo sheet metal small

At close range, it is always easily recognisable on both devices. At greater distances, it is not visible in a vertical position; echoes only became visible when the mast was tilted. For an optimum echo, the reflector must be mounted in the rain catcher position, but this can only be the case either in an upright or tilted (in the test) position. Mounting is difficult, the metal sheets are sharp-edged.

  • Weight: 0.45 kg
  • Reflective surface, total: 3.0 m²
  • Price: 33,92 €
  • Distribution: Bukh Bremen
  • Dimensions: 215 x 215 x 280 mm
  • Rating: ***

Plastimo sheet metal RORC

Plastimo sheet metal RORC

The big brother is consistently easier to recognise on both devices at close range. From a greater distance, the solid-state radar struggles with reproduction. On the radar, the reflector cannot be seen in an upright position; when the boat is heeled over, it blends in with the tug echo. The reflector is very large. There is no opening on the inside to feed a stage through; the installation of the reflector on a sailing boat is unclear.

  • Weight: 1.0 kg
  • Reflective surface, total: 7.0 m²
  • Price: 52,48 €
  • Dimensions: 340 x 340 x 470 mm

Echomax EM 12

Echomax EM 12

Good visibility at both distances. A rather weak echo when measured upright on the magnetron radar. At the greater distance, the reflector also clearly stands out from the echo of the tug. Mounting is easy, a foot helps with mounting on the spreader, for example. A spherical cut-out in the centre makes mounting on the stay easier as it can be threaded through. The plates are not sharp-edged.

  • Weight: 0.73 kg
  • Reflective surface, total: 5.5 m²
  • Price: 80,50 €
  • Distribution: Lindemann KG
  • Dimensions: 360 mm

Mobri S2

The rod is only visible as an echo from a short distance, but it is always equally good, regardless of whether it is vertical or inclined. At greater distances, it is invisible on the semiconductor radar. Only the magnetron radar can detect an echo in a vertical position. The reflector is lightweight and easy to install. However, it is more expensive than the similarly performing Plastimo tube. A base for mounting on deck is available.

  • Weight: 0.38 kg
  • Reflective surface, total: 2.0 m²
  • Price: 49 € (as of 8/2022)
  • Distribution: Lankhorst Hohorst
  • Dimensions: 50 x 570 mm

Plastimo pipe small

Plastimo pipe small

At close range, the Plastimo tube is reasonably visible, but the echoes are visibly weaker compared to the Mobri tube. At greater distances, an echo is only recognisable in a vertical position and on the semiconductor radar. The tube therefore reacts sensitively to heeling. Some of the aluminium plates inside are severely bent and not aligned at right angles. Lightest reflector in the test field.

  • Weight: 0.25 kg
  • Reflective surface, total. 2,0 m²
  • Price. 36,53 €
  • Dimensions: 50 x 580 mm

Mobri S4

Same picture as its little brother: no visibility at a distance of 1.5 nautical miles. Only the magnetron radar in vertical position shows a slight echo. However, the Mobri is clearly visible at close range. The twice as large reflective surface compared to the smaller version does not result in a better echo. The extra weight and price are therefore not worth it. Also available with base.

  • Weight: 0.88 kg
  • Reflective surface, total: 4.0 m²
  • Price: € 95 (as of 8/2022)
  • Dimensions: 100 x 590 mm

Plastimo pipe large

Plastimo pipe large

The same picture as with the competitors in tube form: At short distances, the image is usually good, although very small echoes occur with magnetron radar; at greater distances, they are almost completely invisible. Here too, the larger reflective surface does not result in a better echo. The aluminium plates inside are also bent and not mounted at right angles. The workmanship does not look very high quality due to the burrs on the plastic.

  • Weight: 0.90 kg
  • Price: 62,83 €

Echomax 230 BR

Echomax 230 BR

The very large device is the only reflector that produces an echo under all conditions and regardless of the radar technology. However, these are sometimes rather weak, especially if the reflector is tilted. If the reflector is upright, very good echoes are consistently displayed. The Echomax is very large and heavy, the required mounting bracket costs extra, but is very solid. Rather for large ships.

  • Weight: 2.5 kg
  • Reflective surface, total: 24 m²
  • Price: 301,07 €
  • Dimensions: 245 x 610 mm
  • Evaluation: ****


The 3Lenzz shows consistently good echoes at short distances. At greater distances, reliable echoes are only visible when the device is mounted vertically. If the device is tilted, a strong echo is only visible about every third round, but it is reliably visible in the same place. This is probably a consequence of the three-part design, see running text. The 3Lenzz is the most expensive and heaviest reflector in the test.

  • Price: 389 €
  • Distribution: Northwest radio
  • Dimensions: 300 x 300 x 150 mm

Echomax EM230i

Echomax EM230i

Very good and clear echoes throughout thanks to the large projection surface. Due to the suspended mounting, the reflector is always aligned vertically, so no curved values were measured. Due to its low weight, it is the ideal addition for small cruisers who only want to use the reflector when necessary. As with the ball, we recommend replacing the reflector after five years. However, it is very expensive in comparison.

  • Weight: 0.42 kg
  • Reflective surface, total: 17 m²
  • Price: 296 €
  • Dimensions: 300 x 750 mm

Plastimo inflatable

Plastimo inflatable

Good visibility at short distances, barely visible at greater distances. As the ball always hangs vertically when it is hoisted on a flag halyard, for example, there were no measurements when tilted. Rather poor echoes despite the comparatively large reflective surface. Unfortunately, the ball was leaking, so that constant re-inflation was necessary. The reflector is very large and light when inflated. Expensive.

  • Weight: 0.6 kg
  • Reflective surface: 10 m²
  • Price: 268,94 €
  • Dimensions: 615 mm

11 radar reflectors in the test

It used to be like this: after the radar unit was switched on, it took quite a while for the first image to be taken. This was because the electron beam tube, the magnetron, had to heat up first. This took time and required a lot of energy. Operating the devices also swallowed up a lot of electricity. So, on long patrols in areas with little traffic, it was only allowed to carry out a sweep every few minutes. If nothing was seen, the device switched back to stand-by mode and only used the energy required to keep the tube at the right temperature.

Modern radar devices solve this differently. There, it is not tubes that generate the signal, but semiconductors. They can also generate signals of different wavelengths. As a result, the radar is available as soon as it is switched on and requires much less power. In addition, the radiation is significantly lower, which is good for the health of the people on board. A broadband or semiconductor radar generates roughly the same radiation as a smartphone. Due to the different wavelengths, the radar can generate even more information from the reflected signals. So-called Doppler radars quickly recognise whether an echo is approaching or moving away and in which direction it is doing so without the need for complex plotting. This makes it possible to calculate the point of closest approach and the time until then.

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  • Marine Electronics

Tri-Lens Radar Reflector

yacht radar reflector test

In the September 1995 issue, we reported results of radar reflector testing done at the Stanford Research Institute in Palo Alto, California. This was made possible thanks to Dick Honey, then a semi-retired senior principal scientist at SRI, uncle to former SRI research engineer, well-known navigator and sailor Stan Honey (also the guy who puts the yellow first-down band across the screen of your TV during pro football games). Stan also assisted, as did West Marines Chuck Hawley and a third member of this Bay Area brain trust, Jim Corenman.

Two Types Marine radar is of two types: X-band and S-band. The former is the type commonly carried aboard small boats. It operates at a frequency of about 9.4 GHz (9400 MHz) and has a wavelength of 3.2 centimeters (cm). S-band radar is used aboard large ships and operates at 3 GHz with a wavelength of 10 cm.

Ship operators generally use their X-band radar near shore because it has better resolution and can pick up smaller targets better than S-band, which is commonly preferred offshore due to its longer range and superior resistance to sea clutter.

Terms Radar reflectors are described in terms of their Radar Cross Selection (RCS) and their performance is measured in decibels (dB) relative to some reference, usually a 1m2 sphere (profile).

Tri-Lens Radar Reflector In our 1995 test, a recommended minimum average RCS of 2.5 m2 was adopted at the suggestion of GEC Marconi, maker of the Firdell Blipper reflector.

Radar reflector performance is a direct function of size, proportional to the fourth power of its linear size. Doubling a reflector’s size increases its effective area 16 times. In the 1995 report, we wrote: “As the smallest dimension of a reflector gets down to a few wavelengths of the radar signal, it quits acting as a reflector and starts to act as a lump of metal. Remember that a wavelength is 3.2 cm (1-1/4″) for X-band, and 10 cm (4″) for S-band. So, small reflectors must be looked at with a great deal of suspicion, as there really is no substitute for size.”

Besides strength of return, consistency also is critical. Many radar units are not continually monitored but set to automatically sound an alarm if a target registers three consecutive “hits.” One big hit wont alert the ship’s crew that a smaller vessel is in the vicinity.

Reflectors tested in the 1995 report included the octahedral Davis Echomaster and Emergency; the trihedral and dihedral-based Holland Yacht Equipment, Firdell Blipper, Mobri, High Gain Rotation and Cyclops; and the Luneburg lens-type Lensref. We also tested the Radar Flag, which was practically invisible.

1995 Results The top-performing reflector six years ago was the Davis Echomaster in the vertex up position with 0 heel, which registered 63% of returns above 2.5 m2. In the double-catch rain position and 20 heel, just 43% of returns were above 2.5 m2.

The Lensref has virtually no nulls; its polar plot is a virtual circle. Had the minimum average RCS been just 2.0 m2, the Lensref would have easily won with 100% of returns greater than the threshold. At 2.5 m2, however, just 30% of the returns exceeded the threshold. And this was at less than 18 heel, over which its performance fell off dramatically. A gimbaled mount was recommended.

The Tri-Lens Last year, we were contacted by Tim Rozendal of Rozendal Associates in Santee, California, asking us to test his new reflector. Tim said he has supplied more than 20,000 Luneburg lenses to the US Navy, Army, Air Force and Coast Guard. When he became interested in developing a product suitable for the recreational boating industry, he studied our 1995 SRI report and came up with two sizes of the Tri-Lens Radar Reflector. Due to computer problems at SRI, we were unable to have Rozendals Tri-Lens tested in the same anechoic chamber as the others. Instead, we directed Rozendal to Ohio State Universitys Electro Science Laboratory Compact Range. A copy of the 1995 report was supplied to OSU so that the same test protocol could be followed, and a Davis Echomaster was also tested as a control.

The Tri-Lens has a novel configuration of three modified Luneburg lens reflectors oriented about a vertical axis. It was measured only at X-band.

We asked Dick Honey to review the OSU report and interpret the data. In his summation to PS, he said the Tri-Lens shows “the uniform azimuthal response expected of Luneburg lenses, as well as the excellent tilt (heel) response expected from the design, i.e., each lens looks only into its 120 azimuthal sector so that the spherical reflector on the back of each lens can be quite large, with no aperture blocking as occurs with most single Luneburgs designed for 360 coverage. In other words there are very few narrow angular gaps in the coverage between each lens.”

At 0 heel, 90% of returns exceeded the 2.5 m2 threshold; at 20 heel 70% exceeded the threshold and at 25 heel 69%. The Tri-Lens easily outperformed all other reflectors in the 1995 test.

Honey nevertheless had criticism of the Tri-Lens.

“Our reservations,” he wrote, “are not with the angular coverage, but with the magnitude of the reflection. (This same reservation applies to virtually all passive radar reflectors on the market today!) The Rozendal reflectors use 5.25-inch diameter spheres inside a somewhat larger radome, the spheres being approximately 4.2 wavelengths across at X-band, but only 1.4 wavelengths across at S-band. This means that they may not be much better at scattering S-band radar signals back towards the radar than the average winch, and S-band may be the only radar in use on the high seas (if any).

“As mentioned in our earlier test, the radar cross-section (RCS) of similar reflectors increases as the fourth power of the size, so it would take a relatively small increase in the size of the Luneburg lens to bring the X-band RCS up to 10 square meters (m2) the minimum echoing area requirement in the latest International Standard (ISO 8729, Marine radar reflectors, sec. 5.1.1). That is, a perfect Luneburg lens 5.25 inches in diameter should have an RCS of about 2 m2 at X-band, but a lens only 40% larger or 7 inches in diameter should have an RCS of 10 m2. In addition, it would have a 2-wavelength diameter at S-band, where it might begin to reflect better than a winch. Unfortunately, this would add significantly to the weight of a Lens-based reflector, and weight is already a concern with these reflectors, relative to an octahedral reflector like a Davis Echomaster.

“Rozendal also offers a Mini-Lens reflector, which as expected given its small size, cannot compete with any reflector on the market except for the Mobri.

“Wouldnt it be great if a radar reflector could achieve an RCS of at least 10 m2 at X-band over 360 of azimuth with trivial nulls and wide tolerance for heel? Of course, it should be less than a foot in diameter, weigh little, and be ‘almost free,’ as they say in Mexico.”

In response to these criticisms, Rozendal agrees that the Mini Tri-Lens “does not perform well using the 2.5 m2 threshold.” The Mini Tri-Lens, he says, was “intended for small boats and coastal sailing. It should be mounted as high as possible, preferably on top of the mast. The mini Tri-Lens does not have a large RCS but gives a consistent return. It has three narrow dead spots. The Mobri has 16 dead spots and any octahedral will have eight dead spots. A premium must not only be put on RCS but on the consistency of the return as well. Anything that will help improve a vessel’s radar visibility is worthwhile, particularly shorthanded vessels and those without radar.”

The International Standard for Marine Radar Reflectors (ISO 8729) was revised in 1997 and came two years after our 1995 test. In addition to the section 5.1.1 noted above, there are other relevant sections. 5.1.2 requires that a reflector’s azimuthal polar diagram “shall be such that its response over a total of 240 is not less than 2.5 m2. The response shall not remain below this level over any single angle of more than 10.”

And section 5.2 states, “The performance of the reflector up to at least +/- 15 from the horizontal (the degree of heel) shall be such that its response at any inclination remains above .625 m2 over a total angle of 240.”

Rozendal asserts that “This specification was written around the performance spec of the largest Cyclops unit (it weighs approx. 22 lbs.). They claim their unit is the only passive reflector that meets ISO 8729. No aluminum octahedral reflector is technically able to meet this specification. The Tri-Lens exceeds this specification.”

The standard Tri-Lens measures about 12″ across, is 6″ high, and weighs about 5.5 lbs. It sells for $219 and the Mini version for $129. West Marine now carries them. Price includes a Mast Mount Bracket and a coupler that can be adapted to any marine antenna mount.

As for Honey’s wish for a 10 m2 RCS/360 reflector, Rozendal said he does make a large Tri-Lens using 8″ diameter lenses. It has a RCS of 10 m2 for 300 and minimal degradation when in elevation. It weighs around 15 lbs. and sells for $699.

While bigger is better when it comes to radar reflectors, there are practical limits aboard small boats. Installing a radar unit may be a skipper’s best defense against collision at sea-the idea being that the best safeguard is for you to see the other guy rather than hoping he sees you-but not everyone wants or can afford a radar set. And even then, hanging a relatively inexpensive passive reflector certainly doesn’t hurt.

Compared to the high cost of the Lensref (about $425), the Tri-Lens is a bargain. It costs more than the Davis Echomaster ($60), but outperforms it. If you’re in the market for a passive radar reflector, we recommend the Tri-Lens ( www.tri-lens.com ).

Contact- Rozendal Associates, Inc., 9530 Pathway St., Santee, CA 92071; 619/562-5596

Also With This Article Click here to view “Ranking of Reflectors.”


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  • Radar reflectors

Radar Reflectors

To maximise their visibility to ships navigating using radar as a primary means of identifying potential hazards, including collision situations, boats can be fitted with a radar reflector.

In fact this is a requirement under the SOLAS V regulations:

SOLAS V requires vessels if less than 150 gross tonnage and if practicable, [shall have] a radar reflector or other means, to enable detection by ships navigating by radar at both 9 and 3 GHz.

Essentially this means that if it is possible to use a radar reflector on your boat you should do so, but you should also be aware of the limitations of some of the radar reflectors currently available to you.

X band and S band

Marine radars operate in two bands, the X band (9410 MHz ± 30 MHz) and the S band (3050 MHz ± 30 MHz). X band radars are heavily affected by sea or rain clutter, whereas S band radar assures large target detection in adverse weather. There are now radar target enhancers (RTE) available for recreational use that operate satisfactorily in both bands.

Some passive radar reflectors also respond to both bands but with reduced performance on S Band.

ISO standards

The ISO test standards, with which radar reflectors must comply, are ISO 8729-2:2009 (Active) and ISO 8729-1:2010 (Passive).   

Passive radar reflectors built to the current standard (few, if any, are available) are often too large to be practically fitted to smaller vessels and it is with this in mind that the MCA have issued their guidance. They consider it to be feasible for vessels of 15m and over to fit radar reflectors that comply with the standard, but advise that vessels of under 15m in length should fit a radar reflector with the greatest echoing area practicable.

With this in mind, the critical factors when selecting and fitting a radar reflector remain to ensure a device with the largest possible radar cross section is carried and that it is mounted in accordance with the manufacturer’s instructions. Generally speaking, the higher a reflector is mounted, the better, although vessel operators should take account of the possible effects of the mass of the reflector on the stability of the vessel.

The current ISO test standards in very basic terms require that a radar reflector has:

  • a peak Radar Cross Section (RCS) of at least 10m
  • an RCS of at least 2.5m over an azimuth angle of at least 240° when the reflector is vertical (i.e. not healed over)
  • an RCS of at least 0.625m over an azimuth angle of at least 240° for angles of heal up to +/-15

Radar reflector trials

Over the past few years there have been several trials carried out by the boating press, on how effectively radar reflectors for recreational boats meet these requirements. All seemingly conclude that whatever their manufacturers might claim, some designs are little better than no reflector at all and even the most popular do not always come up to expectations, this is hardly surprising when the IMO requirement is fully understood. 

Laboratory test results on passive units have shown that average RCS values are often much lower than claimed and many reflectors have large nulls (areas where there are virtually no radar returns at all). The physics of radar reflection is complicated and it is notoriously difficult to conduct trials under real conditions at sea where conditions are less than perfect and reproduce test lab results. Given that the reflection from even the best recreational reflector is also affected by positioning, orientation, and angle of heel, you may be starting to get the picture that you might not always appear on the [radar] picture!

The current ISO standards resulted from the IMO requirement set out in resolution MSC 164(78). This IMO resolution recognises that consistency of response is more effective in raising the probability of radar detection than single high peaks. This is defined as a Stated Performance Level (SPL), which is required to be maintained at up to 10 or 20 degrees (two classes recognising the stability differences of power and sailing vessels) either side of the vertical, and limits weight to 5kg and volume to 0.05 m3.

Advice from the MCA

The Maritime and Coastguard Agency (MCA) has issued a Marine Guidance Note on the carriage and use of Radar Reflectors on small vessels.  MGN 349 is a notice to all Owners, Operators, Masters and Skippers of small vessels under 150 tons including Pleasure craft. It can be read in full using the link provided, however in brief the recommendations made in section 4 are as follows:

It is strongly recommended that:

4.1 The requirements of SOLAS Chapter V Regulation 19 are complied with;

4.2 Yachtsmen permanently install not just carry on-board, a radar reflector, or RTE [radar target enhancer] that offers the largest Radar Cross Section (RCS) practicable for their vessel;

4.3 Small craft owners and operators are strongly recommended to fit the best performing radar reflector possible. It is also essential for skippers to be aware that, notwithstanding the type of radar reflector fitted, in certain circumstances their craft may still not be readily visible on ships' radars. They should navigate with caution.

4.4 The following reports published by the Marine Accident Investigation Branch are considered during the process of selecting a radar reflector: http://www.maib.gov.uk/cms_resources.cfm?file=/radar%20reflectors%20report.pdf http://www.maib.gov.uk/publications/investigation_reports/2007/ouzo.cfm

The revision of the test standards have resulted in the introduction from two UK based manufacturers of new active products (RTE’s) to the market, there were, previously a mediocre set of products to select from. The QinetiQ report on their "Performance Investigation of Marine Radar Reflectors on the Market" provides a useful insight into the effectiveness of the products they tested.

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Radar reflector performance

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Because sailboats are notoriously poor radar targets, many sailors purchase a passive radar target enhancer (RTE), or radar reflector, to improve the vessel’s signature. How effective are these devices? For my recent book Radar Reflectors for Cruising Sailboats, I developed a method for describing and comparing RTEs. We’ll use it here to compare a few of the common passive radar reflectors on the market.

The strength of the radar signal reflected by a target is related to the radar cross section, or RCS. A larger RCS means the target will be detected at greater range, by lower power radar sets, in poorer weather conditions and more consistently. Consistent detection is especially desirable for collision avoidance because your vessel may be missed by a human operator and it may be ignored by automatic radar plotting aid software.

Radar reflectors cannot be completely described by a single RCS value. Rather, the RCS depends on the orientation of the radar reflector relative to the radar that is painting it. The orientation, or aspect, is simply the relative bearing of the radar from your vessel and the elevation angle of the line of sight to the radar relative to your deck. For a radar dead abeam, the elevation angle is your vessel’s angle of heel; for a radar dead ahead or astern, the elevation angle is your vessel’s pitch angle. A complete characterization of a radar reflector includes the RCS at all bearing angles, or azimuths from 0° to 360° and all elevations angles from -90° to +90° – although a smaller range of elevation usually is adequate.

Polar diagram

Radar cross section is commonly presented in a polar diagram. To obtain polar diagram data, the target is mounted on a rotating platform in an indoor radar range (radar anechoic chamber). A carefully calibrated radar system records the strength of the reflected signal as the platform rotates through 360° and graphs RCS against azimuth.

A polar diagram describes the RTE as long as it is vertical (elevation is zero). It does not represent performance if the RTE is tilted away from the vertical, as would be the case if the RTE is mounted on a vessel that is rolling or pitching in a seaway or simply sailing at a constant angle of heel. Consequently, single polar diagrams do not provide enough information to compare radar reflectors that are to be used on sailboats. Manufacturers sometimes provide several polar diagrams for different tilt angles, but this is not common practice and, even when the data are available, it is not easy to visualize performance given multiple polar diagrams.

Analytic RCS diagram The data visualization problem may be overcome by a single quantized, color-coded RCS diagram showing the data from many polar plots. Such a diagram is easier to interpret than multiple individual polar plots, but obtaining enough anechoic chamber data to produce a detailed diagram is costly and time consuming. My solution was to develop analytic models of all common RTE, calculate RCS over the entire range of aspect, and present the results in a color-coded analytic RCS diagram. An analytic approach is possible because all RTE are made of a few basic elements that have been analyzed and described thoroughly in the technical literature. Basic elements can be combined analytically to represent any RTE if the physical structure is known. The color-coded diagram allows one to visualize RCS over a large range of aspect and compare RTE with a common display. Included here is the analytic RCS diagram for a Davis EchoMaster 121/2-inch octahedral, mounted in the normal orientation. RCS magnitude is quantized so only six colors are needed. I have used green to indicate an RCS greater than 10 m2, yellow between 5 and 10, dark blue between 2.5 and 5, light blue between 1.25 and 2.5, purple between 0.625 and 1.25, and red less than 0.625 m2. The 2:1 spacing of contours allows six colors to cover a large range of RCS. Essentially, green is good. RCS decreases progressing from yellow to purple, and red means you probably won’t be detected. Examining the diagram, the major feature is the eight circular areas of green, yellow and dark blue centered at about 35� elevation. These correspond to the eight corner cube pockets that are the main element of the octahedral. The narrow vertical and horizontal green areas come into play at certain aspects. This diagram is interpreted as follows. The main response consists of eight cones oriented about 35� above and below horizontal. There is good response at very small elevation angles, roughly �4�, but even at zero elevation, there are small ranges of azimuth for which the response is red. Consequently, this RTE would be marginally useful as long as the vessel on which it is mounted does not heel more than 4�, or heels about 35�. For heel angles between a few degrees and about 20� there is a lot of red. You would present a very small RCS to the radar, and you probably would not be detected at most azimuth angles. There is more red than green or blue over the range of aspect encountered by monohull sailboats, so the octahedral, in normal orientation, may not be the best choice. On the other hand, there is a lot of green and blue for elevation angles less than 4� so this would not be a bad choice for a vessel that does not tilt much. RCS is not the only criterion for selecting an RTE. Cost, mounting, weight and windage aloft, power consumption, and reliability also are important, as is the application, i.e., collision avoidance, search and rescue, fixed navigation aids. Even the type of vessel and expected sailing conditions are important for collision avoidance because of different ranges of heel angle. However, the analytic RCS diagram succinctly summarizes the variation of RCS with aspect and enables one to compare RTE on a common basis.

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By Ocean Navigator

Yachting World

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Radar reflectors – the bad and the ugly

  • Elaine Bunting
  • April 12, 2007

If the performance of radar reflectors and other safety gear is still so poor, why is no independent organisation testing them out?

A few years ago I did a test on man overboard gear and our panel of testers came away with deep reservations about using the sling method of recovery. When I looked into this afterwards I found that although the RORC recommends a Lifesling or similar, it had never tested one. No official body in the UK had ever independently tested any MOB recovery methods.

Ever since then I’ve thought what a pity it is we don’t have such an independent organisation to evaluate the effectiveness of safety equipment we all buy in good faith.

I thought about an independent test panel again when I read the conclusions of the  cms_resources/Ouzo.pdf/?p=234>MAIB’s investigation into the deaths of the Ouzo crew. They report of the octahedral radar reflector that ‘overall performance is poor’ and that there was only ‘a 50% probability [it] would have been seen by the ship’.

As far as I know, all the radar reflectors you can buy for a yacht are somewhere between poor and better than nothing. But it’s only as far as I know. The last major test I can think of was done 12 years ago by  safety/Studies/radar_reflector_test.htm>US Sailing They found that all were marginal – except the radar flag, which was totally useless – and concluded: ‘none of the reflectors would be more than marginally useful in offshore conditions where S-band radar were being used, except perhaps in calm sea conditions’.

It ought to be time to repeat this test, and to look closely at products such as the Sea-Me active radar target enhancer, which have come on the market since this test was done. Isn’t it time somebody in the marine industry set up an independent and authoritative body to properly test reflectors, liferafts, lifejackets and the like?

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Marine Radar Reflectors for Your Boat

As boating becomes increasingly popular, radar reflectors have emerged as an essential element of marine safety. These reflectors enhance the visibility of small boats, allowing larger ships to detect them via radar navigation and collision avoidance systems. 

This article will explore SOLAS Chapter V Regulation and the MCA’s guidance on radar reflectors for small vessels. We’ll also discuss the different types of reflectors, their performance factors, and the importance of proper installation and maintenance. 

Key Takeaways

  • Radar reflectors are essential for enhancing small boat visibility on radar systems.
  • Different types of radar reflectors are available, including passive and active models.
  • Choosing the right radar reflector depends on factors like size, shape, and mounting options.
  • Compliance with SOLAS and MCA guidance is crucial when selecting a radar reflector.

Principles of Radar Technology

Radar (short for radio detection and ranging) is a system that uses radio waves to detect and locate objects. The equipment transmits radio waves using a transmitter and then detects their reflections as they bounce off objects.

By measuring the time it takes for the radio waves to return and the direction they come from, the radar system can determine the distance, direction, and sometimes the speed of the detected objects.

Different Types of Radar Systems

Several types of radar systems are commonly used:

Pulse Radar : This type of radar sends out short bursts of radio waves, called pulses, and listens for the returning echoes. Pulse radar is widely used for navigation, collision avoidance, and weather detection.

Continuous Wave Radar : This radar system emits a continuous radio wave and measures the frequency shift of the returned signal to determine the speed and distance of detected objects. 

Frequency-Modulated Continuous-Wave Radar : This system is similar to continuous wave radar but changes the frequency of the emitted wave over time. This allows the radar to determine both distance and speed more accurately. 

Role of Reflection in Radar Detection

Reflection is a crucial aspect of radar technology. When radio waves encounter an object, some waves are reflected to the radar system. The reflection’s strength and quality depend on the object’s size, shape, and material. Certain materials, like metals, reflect radio waves more effectively than others.

In a marine context, radar reflectors help make your boat visible on other vessels’ radar systems.

Choosing a Radar Reflector 

Radar reflectors increase your boat’s presence on radar by reflecting radio waves more effectively. This is especially important for smaller boats made of materials that don’t naturally reflect radar waves well, like fiberglass or wood. Utilizing one increases the likelihood of other craft detecting your boat, reducing the risk of an accident.

Types of Radar Reflectors

There are two main categories:

Passive : These don’t require power and work by reflecting incoming radio waves to the source. There are several common designs:

a. Corner Reflectors : Typically triangular, corner reflectors are made of three flat metal surfaces joined at 90-degree angles. They are effective but can be bulky.

b. Octahedral Reflectors : Also called “radar balls,” these reflectors consist of eight triangular metal plates forming octahedrons. They provide good radar reflection and are more compact than corner reflectors.

c. Spherical Reflectors : These round reflectors are made of many small, flat metal surfaces arranged in a sphere. They are less effective than the other designs but have a low-profile appearance.

Active : These reflectors require power and amplify and retransmit incoming radar signals. They provide a stronger reflection than passive reflectors but may require maintenance and a power source.

Materials Used in Radar Reflectors

Radar reflectors are typically made from metal, plastic, or composite materials. Metal reflectors offer the best radar reflection but can be heavy and prone to corrosion. Plastic and composite reflectors are lightweight and corrosion-resistant but may not provide the same level of radar reflection as their metal counterparts.

Radar Detection and Boat Construction Materials

The effectiveness of radar detection can be influenced by the construction materials used in building a boat. Different materials can have varying degrees of radar reflectivity, affecting how well a radar reflector performs. Here’s a brief overview of how common boat construction materials can impact radar detection:

Fiberglass: Fiberglass boats generally have low radar reflectivity. Since fiberglass is a non-metallic material, it does not naturally reflect radar waves well. Installing a radar reflector is particularly important for fiberglass boats.

Aluminum and Steel: Metal boats, such as those made of aluminum or steel, have better natural radar reflectivity due to their metallic composition. However, radar signals may be scattered or absorbed by various boat parts, leading to inconsistent radar returns. Installing a radar reflector can help enhance radar presence by providing a more consistent and stronger radar return.

Wood: Wooden boats can have varying radar reflectivity depending on the type and density of the wood used. Wooden boats may generally have better radar visibility than fiberglass boats but may still benefit from fitting a radar reflector to improve their radar signature.

Selecting the Right Radar Reflector

When choosing a radar reflector for your motor or sailboat, consider the following factors:

Size and Shape : Choose a radar reflector that balances size and effectiveness based on your boat’s size and material. Although larger reflectors provide better reflection, they may be more challenging to install or store.

Placement and Height Above Waterline : Mount the radar reflector as high as possible above the waterline to improve visibility. Avoid placing the reflector behind obstructions that could block the radar signal.

Mounting Options : Select a reflector with a mounting system that suits your boat’s configuration. Some reflectors can be mounted on the mast, while others can be attached to railings or other structures.

Regulations and Recommendations : Be aware of any local regulations or recommendations regarding radar reflectors for your type of boat. 

Radar Reflectors: Performance Standards and Trial Results

Marine radars use the X band (9410 MHz ± 30 MHz) and the S-band (3050 MHz ± 30 MHz). X-band radars can be affected by sea or rain clutter, while S-band radar ensures better target detection in adverse weather. Recreational boaters can now use Radar Target Enhancers (RTE) that work effectively in both bands.

Radar reflectors must comply with ISO test standards, specifically ISO 8729-2:2009 (Active) and ISO 8729-1:2010 (Passive). Passive radar reflectors built to these standards are often too large for smaller vessels.

The MCA has issued guidance suggesting that vessels over 15m use radar reflectors that comply with the standard. In comparison, those under 15m should use a reflector with the largest echoing area feasible.

Several recent trials and reports evaluated the effectiveness of radar reflectors for recreational boats, revealing that some designs perform just as poorly as having no reflector at all. Even popular models may not meet the expected performance standards.

Radar Reflectors and Small Craft

The loss of the yacht ‘Ouzo’ and her crew highlighted the significance of radar reflectors for small vessels. To improve the detectability of small boats on radar, the International Maritime Organization’s (IMO) Safety of Life at Sea Convention, 1974 (SOLAS) Chapter V Regulation mandates that ships weighing less than 150 gross tonnage have a radar reflector or other detectable means for vessels navigating using radar, if practicable, at 9 and 3 GHz.

Small craft owners and skippers are advised to select the most effective and appropriate radar reflector or Radar Target Enhancer (RTE) for their situation, ensuring they comply with international standards. The Maritime and Coastguard Agency (MCA) offers detailed guidance on radar reflector selection, installation, and recommendations in MGN 349 (M+F) Amendment 1 .

Testing Your Radar Reflector

Testing your radar reflector is crucial to confirm that it’s performing as intended. Poorly functioning reflectors can cause you to be overlooked by other ships, heightening the risk of accidents and potentially compromising safety.

There are a couple of ways to test the effectiveness:

On-Water Testing : One of the most practical ways to test your radar reflector is on the water. Ask a friend with radar to help you. Move your boat to a reasonable distance from them and check how well your boat appears on its radar screen. Try different distances and angles.

Comparing Reflectors : If you can evaluate multiple reflective models, comparing them while on the water is best. Replace each reflector and note any differences in readings between them.

Understanding Radar Cross-Section (RCS) and Its Relevance to Boat Owners

The Radar Cross-Section (RCS) measures how effectively an object reflects radar waves to the source. A higher RCS means better radar visibility, making your boat easier to detect. Manufacturers may provide RCS values for their radar reflectors, which can help you compare different products. Remember that real-world performance can be influenced by installation and environmental conditions.

Integrating Radar Reflectors with Other Safety Measures

While radar reflectors are important in enhancing your boat’s visibility on radar systems, they should be integrated with other safety measures to ensure comprehensive protection. 

Radar reflectors are just one piece of the safety puzzle. To maximize your boat’s safety, consider implementing the following additional measures:

Navigation Lights : Ensure your boat has proper navigation lights for low light and poor conditions, such as nighttime or foggy weather.

VHF Radio: Maintain a reliable VHF radio onboard to communicate with other craft, receive weather updates, and call for assistance if necessary.

Life Jackets and Personal Flotation Devices (PFDs): Equip your boat with an appropriate number of life jackets and PFDs for all passengers.

Sound Signaling Devices : Carry sound signaling devices, like horns or whistles, to communicate with other boats.

AIS : AIS, or Automatic Identification System, is a technological system that enables data exchange between vessels on the open seas. It allows boats to detect each other’s positions, course, and speed and helps to avoid collisions by alerting them to possible dangers .

Navigating Safely in Areas with High Radar Traffic

When boating in areas with high radar traffic, such as busy harbors or shipping lanes, it’s essential to stay vigilant and follow these safety tips:

Monitor Your Radar : Regularly check your radar system to stay aware of nearby vessels and obstacles.

Use Your AIS : Ensure your AIS functions correctly to broadcast your boat’s information to others in the area.

Operate a Watch : Always maintain a proper lookout, using visual and auditory methods, to stay aware of your surroundings.

Follow Local Regulations : Follow local boating rules and guidelines, including speed limits, navigation channels, and restricted areas.

Properly selecting, installing, and maintaining radar reflectors are crucial for small vessels navigating busy waterways and challenging weather conditions. By enhancing their visibility to other ships, radar reflectors significantly contribute to maritime safety and collision avoidance.

It is essential for recreational boaters and other small vessel operators to be aware of the requirements and recommendations set forth by SOLAS and the MCA and to choose the most suitable radar reflector or radar target enhancer for their specific circumstances. 

However, it is essential to remember that radar reflectors should not replace the need to operate a watch and navigate cautiously. By combining effective radar reflectors with safe navigation practices, small vessel operators can significantly reduce the risk of an accident and enhance sea safety.

A radar reflector is a device that enhances a boat’s visibility on other vessels’ radar systems by reflecting radio waves more effectively.

Radar reflectors are crucial for small boats because they make the boat more visible on radar systems, reducing the risk of collisions and accidents.

There are two main types: passive (corner, octahedral, and spherical) and active radar reflectors.

Consider factors like size, shape, placement, mounting options, and local regulations when selecting a radar reflector.

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Sail trim: speed, stability, and performance, related posts, what should you do first if your boat runs aground, navigation: boat lights at night, handling lightning strikes on boats.

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Installing a new radar reflector

Keep your family safe while sailing with this guide on installing a radar reflector for your boat.

Installing a New Radar Reflector

As you embark on your sailing adventure with your family, safety should always be a top priority. One essential piece of safety equipment that you should consider upgrading or installing on your boat is a radar reflector. In this comprehensive guide, we will discuss the importance of radar reflectors, the different types available, and how to properly install one on your boat.

Table of Contents

Why you need a radar reflector, passive reflectors, active reflectors, choosing the right radar reflector for your boat, mounting options, installation tips, testing your radar reflector.

A radar reflector is a device that helps make your boat more visible to other vessels’ radar systems. This is particularly important in situations where visibility is poor, such as during fog, heavy rain, or at night. By increasing your boat’s radar signature, you can significantly reduce the risk of collisions with other vessels.

In many countries, radar reflectors are required by law for certain types of boats, especially those under a specific size or those that are not made of metal. Even if it’s not a legal requirement for your boat, it’s still a wise investment to ensure the safety of your family and your vessel.

Types of Radar Reflectors

There are two main types of radar reflectors: passive and active. Each type has its own advantages and disadvantages, so it’s essential to understand the differences before making a decision.

Passive radar reflectors are the most common type and work by reflecting the radar signals emitted by other vessels back to their radar systems. They do not require any power source and are generally low maintenance. There are several different designs of passive reflectors, including:

Octahedral reflectors: These are made of metal plates arranged in an octahedral shape, which provides a strong radar reflection from all angles. They are often collapsible for easy storage when not in use.

Luneburg lens reflectors: These are spherical devices made of materials with varying refractive indices, which focus the incoming radar signals and reflect them back to their source. They are less common than octahedral reflectors but can provide a stronger reflection.

Cylindrical reflectors: These are made of metal tubes arranged in a cylindrical shape, which can provide a strong radar reflection when oriented correctly. However, their performance can be significantly reduced if they are not aligned with the incoming radar signals.

Active radar reflectors, also known as radar target enhancers (RTEs), work by receiving the incoming radar signals and then transmitting a stronger signal back to the source. This can result in a much larger radar signature than passive reflectors, making your boat more visible to other vessels.

Active reflectors require a power source, usually your boat’s 12-volt electrical system, and may also require periodic maintenance. They are generally more expensive than passive reflectors but can provide a higher level of safety due to their increased visibility.

When selecting a radar reflector for your boat, there are several factors to consider:

Size and weight: The size and weight of the reflector should be appropriate for your boat. Larger reflectors generally provide a stronger radar reflection, but they can also be more challenging to install and may create additional wind resistance.

Performance: The performance of a radar reflector is measured in square meters of radar cross-section (RCS). A higher RCS value indicates a stronger radar reflection. Look for a reflector with an RCS value that is appropriate for your boat’s size and the conditions in which you will be sailing.

Mounting options: Consider how and where you will mount the reflector on your boat. Some reflectors come with mounting brackets or can be easily attached to existing structures, while others may require additional hardware or modifications to your boat.

Budget: Radar reflectors are available at various price points, so consider your budget when making a decision. Keep in mind that investing in a high-quality reflector can provide increased safety and peace of mind during your sailing adventures.

Installing Your Radar Reflector

Once you have chosen the right radar reflector for your boat, it’s time to install it. Proper installation is crucial to ensure the reflector’s effectiveness and your safety on the water.

There are several mounting options for radar reflectors, including:

Mast mount: Mounting the reflector on your boat’s mast is a popular option, as it provides a high and central location for optimal radar reflection. This can be done using brackets or clamps designed for your specific reflector.

Shroud mount: Another option is to mount the reflector on your boat’s shrouds (the cables that support the mast). This can be done using special shroud clamps or by attaching the reflector directly to the shrouds with cable ties or other fasteners.

Radar arch mount: If your boat has a radar arch, you can mount the reflector on the arch using brackets or clamps. This provides a high and unobstructed location for the reflector.

Pole mount: If none of the above options are suitable for your boat, you can mount the reflector on a dedicated pole. This can be a fixed or removable pole, depending on your preferences and your boat’s layout.

When installing your radar reflector, keep the following tips in mind:

Height: The higher the reflector is mounted, the more effective it will be. Aim to mount the reflector as high as possible while still being accessible for maintenance and inspection.

Clearance: Ensure there is adequate clearance around the reflector so that it is not obstructed by other structures or equipment on your boat. This is particularly important for passive reflectors, which rely on a clear line of sight to incoming radar signals.

Orientation: Make sure the reflector is oriented correctly according to the manufacturer’s instructions. This is especially important for cylindrical reflectors, which need to be aligned with the incoming radar signals for optimal performance.

Secure mounting: Ensure the reflector is securely mounted to your boat using appropriate hardware and fasteners. Regularly inspect the mounting points for signs of wear or corrosion and replace any damaged components as needed.

After installing your radar reflector, it’s essential to test its performance to ensure it is providing adequate radar reflection. This can be done by asking a nearby vessel with radar to check your boat’s radar signature or by using a radar reflector tester, which is a specialized device that measures the strength of your reflector’s radar reflection.

Regularly testing your radar reflector is a good practice to ensure it is functioning correctly and providing the necessary safety benefits.

Installing a radar reflector on your boat is an essential safety measure that can significantly reduce the risk of collisions with other vessels. By understanding the different types of reflectors available, choosing the right one for your boat, and properly installing and maintaining it, you can ensure the safety of your family and your vessel during your sailing adventures.

Yachting Monthly

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Updated guidance on fitting a radar reflector to boats under 15m

  • Katy Stickland
  • November 15, 2022

The Maritime and Coastguard Agency has updated its guidance and is urging all owners of boats under 15m/49.2ft to fit a radar reflector

A radar reflector from the top of a yacht

All boats less than 15m/49.2ft and under 150 gross tonnage should permanently carry a radar reflector. according to the Maritime and Coastguard Agency. Credit: Graham Snook/Yachting Monthly

The Maritime and Coastguard Agency (MCA) has updated its guidance on the use of a radar reflector on boats less than 15m/49.2ft and under 150 gross tonnage. 

Marine Guidance Notice (MGN) 349 states that a radar reflector or radar target enhancer should be permanently installed, and offer the largest radar cross section (RCS) as practical for the vessel.

Commercial ships use radar equipment that operates in the ‘X’ band (9GHz) and the ‘S’ band (3GHz).

A radar reflector on a recreational boat should have a RCS of at least 7.5m² at X-Band and 0.5m² at S-band when mounted at a minimum height of four metres above sea level.

Just because you have a radar reflector, doesn't mean you will be seen. Always keep a proper lookout, advises the MCA. Credit: Graham Snook/Yachting Monthly

Just because you have a radar reflector, doesn’t mean you will be seen. Always keep a proper lookout, advises the MCA. Credit: Graham Snook/Yachting Monthly

The RCS should be maintained over a total angle of at least 280° of azimuth and not below this level over any angles greater than 10° (a null).

There should not be a distance of less than 20° between nulls.

For power driven vessels and sailing vessels designed to operate with little heel, such as a catamaran or trimaran, this performance should be maintained through angles of (athwartships) heel 10° either side of vertical.

For other vessels, the radar reflector should maintain this performance over 20° either side of vertical. Any radar reflector meeting the above requirements should comply with ISO 8729-1:2010.

If the radar reflector meeting these standards are unsuitable for boats under 15m LOA, then owners are recommended to fit a radar reflector to the older standard EN ISO 8729:1998, which has been retained for type approval under the Marine Equipment Regulations (MSN 1874) for radar reflectors for lifeboats and rescue boats.

It should be noted that Echomax has emailed Yachting Monthly to say it has contacted the MCA to express concern over their mention of ISO 8729-1:2010, as currently, there are no known passive radar reflectors which meet ISO 8729-1:2010 which has a volume limit of 0.5m3 and weight limit of 5kg.

In response, the MCA said:

‘The notice will not be amended as it can’t be confirmed 100% that there are no products of this type currently on the market, but it is highly likely during our research that this is the case.

In reference to 3.1.3 of the amended MGN:

‘3.1.3 However the above standard results in a large reflector that may be unsuitable for vessels under 15m overall length, in which case Owners and skippers of craft less than 15m overall length are recommended to consider fitting a radar reflector to the older standard EN ISO 8729:1998, which has been retained for type approval under the Marine Equipment Regulations (MSN 1874) for radar reflectors for lifeboats & rescue boats.’

EN ISO 8729:1998 remains in force until a product is placed on the market approved to ISO 8729:1.’

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The MCA is also advising skippers that in certain circumstances, their boat may still not be readily visible on ships’ radars, even when fitted with a radar reflector or a radar target enhancer, and that this does not replace the need for a proper lookout at all times.

MGN 349 was initially published following the deaths of three sailors aboard the Sailfish 25, Ouzo overnight on 20-21 August 2006.

Rupert Saunders, 36, Jason Downer, 35, and James Meaby, 36, all died when their yacht was sunk six miles south of St Catherine’s Point on the Isle of Wight after a collision with the P&O ro-ro ferry Pride of Bilbao .

The mast of a yacht

Radar reflectors should be mounted at a minimum height of four metres above sea level. Credit: Graham Snook/Yachting Monthly

A report by the Marine Accident Investigation Branch ( MAIB ) found that Ouzo had not shown up on the ferry’s radars and the bridge team on Pride of Bilbao had not seen the yacht until is was very close ahead.

The officer on watch made a last minute manoeuvre to avoid Ouzo and believed he had been successful, although he did not contact the yacht crew to confirm this, and instead relied on seeing, what he thought, was the yacht’s stern light.

The MAIB concluded that the Pride of Bilbao had collided with Ouzo , or passed so close that the yacht had been swamped or capsized by the ferry’s wash. The yacht was never recovered.

The MAIB did commission a report by QinetiQ to carry out research into a number of common types of radar reflectors to compare performance with International Standards (ISO 8729).

The recommendations included:

  • Using a Sea-Me radar reflector where power is available;
  • Making sure the RCS of the radar reflector was a minimum of 2 m²
  • Not using a 4” or 2” tube reflector due to its poor performance.

Details of MGN 349 can be found here.

Details of the full MAIB report into the sinking of Ouzo and the QinetiQ Radar Reflector report can be found here.

Please note this article was updated on 23 November 2022 after YM was contacted by Echomax about the updated MGN 349 guidance, to inform us that there are currently no known passive radar reflectors which meet ISO 8729-1 which has a limit of 0.5m3 and 5kg.

Enjoyed reading Updated guidance on fitting a radar reflector to boats under 15m?

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Ouzo report: Radar reflector test results published

  • May 9, 2007

MAIB / Qinetiq results available to download

The Performance investigation of marine radar reflectors carried out by the defense research agency, Qinetiq in the aftermath of the loss of the 25ft yacht Ouzo last summer, has finally been published today.

Click here to download the MAIB / Qinetiq radar reflector report

The results, which were delayed due to consultations with radar reflector manufacturers can be summarized as follows:

*None of the nine units tested meets the the forthcoming draft ISO8729 [2] standard, which requires a 7.5 square-metre radar cross section (RCS) at angles of heel up to 20° for yachts, although one of the units was compliant to the angle stipulated for powerboats and catamarans of 10°

*Only one of the units tested claimed to be compliant with the existing standard ISO8729 – however, this performance was not recreated in the Qinetiq tests.

*Several of the units tested did conform with the current ISO8729, despite not holding ‘type-approval’.

What was Ouzo carrying? Ouzo is known to have been carrying a ‘six-inch octahedral radar reflector’ although the MAIB report of 12 April does not state what make.

The MAIB report states: ‘Although any radar reflector is better than none, the type of reflector fitted to Ouzo can theoretically produce a reasonable peak increase in the RCS but, in practice, its overall performance is poor, and it is now evident that at best there was only a 50% probability that the ship would have been able to detect Ouzo on the radar at close range.’

The Qinetiq report states that short-range visibility (less than 2.6NM) of a radar reflector is very poor with an RCS of one metre squared. The current ISO8729 only requires 0.625 square metres RCS at all angles of heel up to 20°.

It continues: ‘For radar reflectors with an RCS of two square metres and above the probability of being tracked inside 2NM increases significantly’

Items on test The report tested nine products ranging in price from £16 (Plastimo 16″) to £2,000 (POLARef 11) in a lab, simulating 16 knots of windspeed and swells of 5ft:

Plastimo 16″ Octahedral & 4″ tube Davis Echomaster Viking Tri-lens Large & Standard Echomax 230 Firdell Blipper 210-7 Sea-Me POLARef 11

The reflector height was 4m with the Bridgemaster radar scanner at 30m. The reflectors were tested for radar cross section (RCS) – measured in square metres – at angles of heel from 0° to 20°.

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Install a Marine Radar Reflector

  • Written by Andrew T. on Feb 02, 2010 To ensure our content is always up-to-date with current information, best practices, and professional advice, articles are routinely reviewed by industry experts with years of hands-on experience. Reviewed by H.R. Helm on Jan 22, 2020
  • 2-6 hours •
  • Beginner •

A marine radar reflector is used as a way of making small boats stand out on radar systems. Radar works by sending out radio waves and then drawing a picture based on the reflected radio waves. The larger the object, the bigger the reflection. A very small boat will only be shown by a small radar reflection.

A marine radar reflector will make boats more visible to other boats using the RADAR system.

Step 1 - Reasons for Radar Reflectors

Boats made out of wood or fiberglass are not normally as visible on radar systems as often as metal boats. A radar reflector can be used as a way of making your boat more visible. If you have a non metallic boat then people may find it very difficult to identify your boat on radar systems, this can put you in unnecessary danger which is why radar reflectors are so important.

Any non metallic fishing boat will need a radar reflector as a legal requirement. This needs to be visible for at least 6 miles legally.

Step 2 - Positioning the Radar Reflector

A radar reflector is quite simply a large metallic object which is fixed to your boat. Therefore, it's important that the device is fixed well above the waterline of your boat for optimum effectiveness. The metallic object can be fixed in a number of different ways. The radar reflector will need to be mounted on a pole on your boat. Choose the biggest radar reflector that your boat can accommodate.

The radar reflector needs to be located as high up on the boat as possible, by doing this you will maximize the chances of it effectively helping other sailors to identify your boat. Make sure that you locate this somewhere high up, but somewhere that won't impair the performance of your boat. This is something that you will have to think about carefully to get the best all round result.

Step 4 - Mounting the Radar Reflector

The radar reflector needs to be physically fixed to the boat, this can be done using a large pole or support. A large pole needs to be bolted onto the top of your boat and then the radar reflector is fixed to the top. The radar reflector is simply bolted onto the pole so that it can't move.

Weather conditions out at sea can be vicious at times, the radar reflector needs to be securely fixed so that it can't come loose even in the harshest of weather conditions.

Step 5 - Testing

Now all you need to do is test that the radar reflector really does make your boat more visible. Get another boat to try and find you to check if this works. The more visible you are, the less dangerous sailing is. The sea is full of huge commercial vessels, which is why it's so important to make yourself stand out. This will prevent any accidental collisions which could not only be costly, but also dangerous.

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