On the morning of 28 February 2009, Wismar Bay is in the area of influence of a warm front. The wind is blowing from the east at 2-3 Beaufort, the air pressure is 1010 hPa and visibility is reported to be around 300 metres. This is what it says in the logbook of the "Christa", a former fishing cutter, which sets sail from Wismar harbour with 35 people on a deep-sea fishing trip and heads for the flag low.
The skipper is alone on the bridge and uses the radar due to the poor visibility. At the same time, the motor vessel "Odin" is moored at the approach buoy Timmendorf on Poel with the engine stopped. The owner has noticed water in the boat and sets off with his partner to find the cause. He notices the approaching "Christa" at a greater distance, but does not recognise the danger and continues to focus on damage limitation.
Only when the cutter is on a collision course and only about 100 metres away from the "Odin" do the two try to make themselves noticed by waving, shouting and blowing their horns. Unfortunately in vain. The crew of the "Odin" saved themselves at the last minute by jumping into the water to escape the danger zone. The other crew only spotted the motorboat 30 metres before the collision, but were unable to prevent the collision.
"The crew of the "Christa" only spotted the motor vessel 30 metres before the collision, but were no longer able to prevent the collision."
According to the skipper, he had no visual or radar contact with the "Odin". The stern of the "Odin" is torn off on impact and sinks immediately. The crew drifting in the water is picked up and cared for by the "Christa", which is only slightly damaged. - In its investigation report, the Federal Bureau of Maritime Casualty Investigation (BSU) also deals in detail with the visibility conditions, the use of the radar and the lack of a radar reflector on board the "Odin", among other things. The fact that the motorboat was sighted so late is initially due to the poor visibility, but also to the fact that there was no radar reflector on board and the ship's command of the "Christa" therefore did not perceive a radar echo. - In its analysis, the BSU also argues as follows under point 6.3:
"It is possible that a radar reflector could have improved the visibility of the motorboat on the radar screen of the "Christa" and thus prevented the collision."
That brings us to the topic. The SOLAS Convention (Safety of Life at Sea) stipulates that recreational craft under 150 GT, i.e. all boats in the usual categories built after 1 July 2002, must be fitted with radar reflectors. These must be approved and be recognisable by ships with radar equipment on both 9 GHz and 3 GHz. First of all, very few of them actually are, because the manufacturers are afraid of the costs of certification or the standards are not sufficient. On all pleasure craft built before 2002, "seaman's duty of care" requires the installation of a radar reflector, at least when visibility is reduced or at night. This somewhat plum-soft formulation offers scope for interpretation in many directions.
"The investment for a reflector is almost ridiculous in relation to the safety plus: you can get a passive device from as little as 40 euros in any better accessory shop."
Not compulsory, but useful
However, this passage gains enormous importance at the latest during the judicial investigation of a marine accident, and the insurance company's expert in particular will deal with this topic in detail and write a corresponding assessment for his client. If it turns out that the accident could have been avoided by fitting a radar reflector, the whole thing ends with potentially catastrophic financial losses for the skipper or owner.
Overall, radar reflectors are now widespread on pleasure craft. Unfortunately, however, far too many are still not equipped with them, and often the sense of such an installation has not yet penetrated everyone's minds.
Anyone who argues that they only sail in good weather, during the day and in the area they know has never been caught in a thunderstorm with pouring rain, in a sudden haze or accidentally in the dark. As long as there is no other shipping traffic to be expected, the skipper has to decide for himself how to deal with it. However, at the latest when he is no longer travelling alone, he is not only endangering himself in such conditions, but also others. The investment for a reflector is almost ridiculous in relation to the safety benefits. You can buy a passive device for as little as 40 euros in any better accessory shop, albeit with only average effectiveness.
That brings us to the technology. Radar reflectors are also called angled reflectors for good reason. Several electrically conductive surfaces arranged at an angle of exactly 90° to each other reflect radar waves in exactly the direction from which the pulse is transmitted. This produces a clearly visible signal on the observing radar screen, and it is possible to identify an object (boat) with a smaller reflective surface even at a greater distance. Smaller yachts without a reflector, especially if they are GRP constructions, offer little resonance here, and if the angle to the transmitted radar beam is also reduced due to the course, such a target quickly becomes invisible.
"The reflectors are only 100% effective in a truly vertical position. If the position changes by more than 5° to the vertical, they can quickly become ineffective."
It is therefore important to use a system in which the angular radiation is as effective as possible around 360°, so that optimum reflection is always ensured regardless of the course. This means accommodating as many angles as possible in a manageable space. To achieve this, they are mounted in a plastic tube, for example, and the wavelength is matched to that of the radar. Even with the smaller commercially available radar reflectors with a length of 30 cm and 10 angles, a reflective surface of at least 2 square metres is created, generating a return signal that is four times larger.
However, if we arrive at a reflective area of 10 square metres, this corresponds to the size of a medium-sized motor yacht on the radar screen. However, it only becomes really effective from an area of around 20 square metres. So the simple formula applies: The more angular systems, the more reflective surface, the more voluminous the reflector, in short: the larger - the more effective. They are available as transparent tubes from 55 to 78 cm in length, as space-saving inflatable tubes, as plug-in cubes or in various sizes concealed in voluminous plastic cylinders, up to the size of a medium-sized fender. Not everyone's cup of tea due to the size, but a good increase in safety.
Safety before design and appearance
Nevertheless, many recreational boaters have reservations when it comes to the size of radar reflectors. Many people are reluctant to use bulky models on the equipment carrier for aesthetic reasons alone, but they also have to accept a minimised safety standard. It should not be forgotten that waves above a certain size also generate echoes on the radar, and if the reflector is too small, a boat equipped in this way quickly becomes invisible. What's more: The reflectors are only 100% effective in a truly vertical position. If the position changes by more than 5° to the vertical, they can quickly become ineffective. A tip for emergencies: If the weather and visibility unexpectedly drop to the lower limits and there is no radar reflector on board, a frying pan or a large pot from the galley will do the trick. Mounted on the mast or equipment rack, they at least produce a reflection - albeit a marginal one - and allow us to bob around without being completely invisible. But please don't sail with the frying pan in the top in future, it really is only a last resort.
So far we have been talking about passive systems with angled reflectors. However, tri-lens reflectors (Lüneburg lenses), for example, are much more effective and the most optimal systems of all are active radar reflectors. The Lüneburg lens, developed by the mathematician Rudolf Karl Lüneburg, is a sphere coated with dielectric material that sends the parallel incident waves back in the direction of their source. Three such spheres arranged in a corresponding casing provide a maximum constant return radiation pattern without minima or gaps.
They have long been used in military applications due to their high performance. They are now also available for recreational boating. This added security is available from accessory dealers for around 220 euros. Not a big deal compared to the total cost of a motor yacht. You have to invest around three times as much if you opt for an active radar reflector, which is recommended by the BSH. A transponder such as the Echomax Active in the X-band costs around 650 euros, while the XS-band costs around 1000 euros. In relation to the increase in safety, this is also an investment that is really worthwhile.
The drastically increased range and comprehensive shielding is enormous, and the amplified incoming pulse on the radar screen cannot be overlooked by other ships. The way it works is easy to explain: signals received from other radars in X-band mode, and since 2009 also in S-band mode, are amplified and reflected by an electronic system. Smaller ships can thus be identified at distances of around 12 nautical miles, instead of 3-5 nautical miles as was previously the case with angle reflectors.
The average reflective surface is a decent 111 square metres, and even at an angle of 20° it is still almost 20 square metres. An acoustic warning signal also indicates any radar units in the vicinity. Apart from their performance, active reflectors also have the advantage that they are very slim and can be mounted easily and almost inconspicuously on almost any boat. Disadvantages: They are comparatively expensive and consume power. Around 15 mA in stand-by mode and up to one watt in transmit mode.
Conclusion
Let's be honest, don't we also spend a lot of money on all kinds of bells and whistles for our boats? Shouldn't our own safety be worth this important investment? And wouldn't it be reassuring if we received the answer to the radio question "Can you see me?": "Yes, we have you clearly on our screen!"?
