One of the most comprehensive tests of radar reflector performance was carried out in 1995 by West Marine www.ussailing.org. The conclusions were that the poor performance of the Firdell Blipper 210/5 and 210/7 were surprising given their popularity and reputation, and although a well packaged and clever device, the models tested (i.e. 210-5 and 210-7) were not large enough to have much value aboard a vessel. Furthermore, they were also unable to obtain results consistant with those supplied by Firdell, stating that their claims were consistant with a larger reflector. The Echomax range is included in the 2003 West Marine catalogue, replacing the Firdell Blipper.
Prior to publishing their test results West contacted Firdell for their comments. Firdell claimed that only Target Pattern Maps were reliable. Thereupon West further tested the unit using Target Pattern Mapping and found it made no difference to their original findings.
Similar conclusions were drawn in the Practical Boat Owner test published in a series of articles see issue 391 July 1999. “Having so many reflectors close together produces a polar plot made up of several spikes ‘a good response’ separated by an equal number of deep interference troughs in which the reflection from one corner reflector cancels out the reflection from the other.”
In 1993 the Trading Standards Authority forced Firdell to reprint their literature removing the claim that the Firdell Blipper met ISO 8729, RORC and ORC regulations. False claims still persist in Chandlery catalogues and on the Internet. Firdells current literature only refers to a highly volumetric structure but still makes false claims about 360 degrees performance at 2.5m2 at +/- 15 degrees of heel. As will be seen from the polar diagram below they do not achieve this performance in the vertical position. To say they only have six nulls over 10 degrees is generous. They do not have a website and have little published data on their reflectors. The target pattern map we managed to get from them was coloured in by them with crayon!
RCS Peak M2
Response below peak
Performance @ 1.25m2
Performance @ 2.5m2
+ or - 3 Degrees heel
Performance @ 5m2
Performance @ 10m2
+ or - 9 Degrees heel
+ or - 15 Degrees heel
+ or - 20 Degrees heel
Distance between centres
Echomax EM230 & BR
12 peaks 20m2 @ 30 Degree intervals
24 sq m @ 2.5 m2-no nulls
19 sq m peak @ 2.5m2 no nulls
10 sq m peak
5 sq m peak
April 2001 6.3m2, Nov 2001 7.96m2
Peaks - 4m2 & 5m2
7.96 Seven nulls exceed 10 degrees
7.0 Seven nulls 28.5% (102.6 degrees)
7.0 Seven nulls 45% (162 degrees)
The above test results were obtained at QinetiQ (DERA) in April/November 2001 and May 2002
Active X v Sea-me RTE
Comparison below has been made with the Sea-Me RTE which has received very good yachting press reviews and is reputed to be the best selling RTE in the UK.
The Sea-Me RCS response data was obtained from the March 07 MAIB Performance investigation of marine radar reflectors following the Ouso disaster or the Sea-Me RTE manual. RCS response data source Active-X QinetiQ 13th March 09.
Active XS v Sea-me Dual band
698 x 50mm
685 x 40mm
Stand by current
Audible alarm (internal)
External alarm facility
One for both
X and S
Two Green for X
Yellow for S
Source PBO August 2010 based on Sea-Me published QinetiQ linear charts
Echomax Active XS voted PBO August 2010 Best Buy
Transmit current S Band
Transmit current X band
Max SPL Zero deg S band
Max SPL Zero deg X band
Max SPL 20 deg S band
These figures illustrate the "Trilens" 5 inch diameter reflector, for which they claim 2 to 4m2 RCS, will be hidden in moderate clutter. They also state it's performance is comparable to a 12 inch corner. Presumably they mean a 12 inch octahedral RCS 2.21m2. The RCS of a single 12 inch corner is 35m2.
In free space a
4m2 target's RCS at
1.5 n.mile - 0.8m2
2 n.mile - 0.25m2
In average precipitation at
0.5 n.mile - 2m2
1.5 n.mile 0.3m2
2 n.mile - 0.08m2
0.5 n.mile - 4m2
The only 'TriLens' reflector, to meet ISO 8729, RORC and ORC regulations is their 20 inch diameter, which weighs in excess of 15 pounds, and costs US$699. Hardly suitable for yachts!!
Rosendal's (TriLens) web page compares their Mini-TriLens with a Mobri reflector found 'invisible' by West Marine.
The performance of other reflectors, given below, was examined by QinetiQ in the presence of independent observers.
** Latest literature we have seen accompanying Visiball states that "its computer generated surfaces ensures a consistent performance through 360 degrees and its special filling maximizes the reflection." Our tests at QinetiQ only gave a response of 1m2 for 195 degrees. The balance of 165 degrees being virtually zero response, as will be seen from the polar diagram shown to the left.
Sailing Today sea trails September 2009
Visiball declined to submit a unit for test as invited
Sailing Today Quote: 'We were unable to discern any real difference when heeled at 10 or 20 degrees'
** Sea trials ceased at 7.3 nm due to number of radars transmitting in the area.
The following reflectors do NOT meet ISO 8729 and therefore do not satisfy SOLAS Chapter V, RORC or ORC requirements:
- Mini-Trilens, Trilens 5.25 Inch lens, Cyclops I & II, Mobri 50mm/100mm, Blipper 210-5/210-7, Pains Wessex SC4, all Octahedral based reflectors under 18 Inches Diameter, including Davis Octahedral, VisiBall.
If there is any doubt, ask the respective manufacturer for their test results.
OCTAHEDRAL REFLECTOR has been in use for over 65 years and the 18 inch has been the benchmark by ISO/BSI and RORC and forms the basis of the current ISO 8729 with a peak of 10M2. However its weakness is at 15 degrees of heel where the response falls to just 0.625M2 and at this angle there is no response over 140 degrees azimuth. The reflector in the catch rain position gives a good response but in many instances the reflectors are poorly positioned, particularly when installed in back stays, which renders them next to useless.
Stacked tube reflector
Probably one of the best selling reflectors as they are relatively cheap, easy to install and come in halyard mount or with deck mount bracket fitted. Refer to www.ussailing.org where they found these units to be 'invisible a useful addition to a stealth bomber'.
The advantages of RTE's are well known, both for their compactness and excellent performance both from the measured results at Funtington and during the live trial at Fraser on 1st. March 2002.
It is interesting to note that active RTE's were initially specifically excluded in the revision to ISO 8729, as, under certain conditions, a radar display can be violently disrupted due to the unwanted response of one or more radar target enhancers causing an inter-reaction leading to self oscillation of the RTE.
This phenomenon was observed in anechoic room experiments and field experiments undertaken in Japan.
Technology has moved on since the early days of the revisions to ISO 8729 so much so that a new standard ISO 8729-2 was drafted specifically for active devices encompassing tests to ensure self oscillation would be engineered out of a product before it could meet the revised standards performance criteria. The Active X passed this section of the tests with flying colours!
The reliable response of an RTE requires a continuous ships electric supply, component reliability, good design and quality build standard.
The “Active-X” with its miserly quiescent current drain and “cutting edge of technology” design and manufacture under ISO 9002 conditions goes a long way to overcoming the problems of products of an older and less efficient design.