RADAR REFLECTORS
RTE POWER DRAW REGULA
‘
TIONS
Standby power with no ships in range The SOLAS regulation V/19 requires
was easy to measure, at 14mA for all small craft to fit a reflector ‘if
Active-X and 92mA for Sea-me. practicable’. If the vessel is over 15m
Power consumption when receiving and LOA it is mandatory and must comply
transmitting was more diffi cult to with IMO requirements. The MCA notice
measure because the consumption is MGN349 gives further information, but
constantly changing. Accurate a revised standard for radar reflectors
equipment for recording consumption (ISO8729) came into force in July 2009
over time was not available. At Warsash, with much more stringent requirements.
with just one or two target radars, Incredibly, at the time of going to print,
Active-X used 14-47mA, whilst Sea-me no passive radar reflectors on the
used 90-110mA. Fully loaded, in sight market meet the new standard.
of more than 10 radar targets on the We contacted the MCA about this
waterfront at Lee-on-Solent, Active-X and they replied:
used 50-190mA and Sea- “The MCA is aware of perceived
me 90-190mA. shortfalls in this particular standard and
all relevant comments and suggestions
Manufacturer’s power were made during its development.
consumption figures During the development of this standard
Active-X: Standby <15mAh, the MCA was unable to convince the
5 active radars <22.9mAh, majority of its concerns. The standard
10 active radars <31.2mAh. has now been published and is in
Sea-me: Standby 150mAh, force.” Mark Clark, MCA.
transmitting 350mAh.
WHICH ONE WORKED BEST?
Think of a series of circles around the
Why are the results so similar? What lessons were learned?
target boat, like a dartboard. The inner
circle extends to about four miles and Getting good results on a radar screen The test team agreed that in an ideal world
within this the combination of boat and is more about getting a consistent return we want a radar set and AIS on our own
refl ector response is more than enough to than a strong one. Modern radar sets boat, so instead of hoping that other vessels
give a good paint on the radar, i.e. it does have very clever software assessing see us, we can actively hunt for targets and
not matter if it is stronger, because enough the incoming echos, so if a return is take action to keep out of their way. If you
signal is being received. The second circle consistently viewed from a particular can’t fi t a radar or the budget won’t go that
is from about four to seven miles, where place – regardless of how strong the far, you will get better performance from an
the response from a passive and signal might be – the radar interprets active RTE than a passive refl ector, with the
the boat is no longer this as a target and paints it on added advantage that the device will tell you
enough to saturate the the screen. For that reason it when it is being painted by a radar, so you
radar, so the paint is not possible, until know a vessel has you on her radar screen.
fades. Here the you reach extremes of We also learnt that a production 35ft
active units will range, to say that one cruising yacht is quite a good radar refl ector.
increasingly make refl ector is better than In all our tests the boat was stern-on to the
a difference. From another, but only that tracking radar, so we think it’s likely that the
seven miles one shows up and mast and rigging played a part in making the
outwards only the other one doesn’t. yacht on her own quite visible. It’s an urban
the actives will Only when we got myth to claim that big metal parts inside the
show a paint, the beyond four miles boat, like the engine, help to give a good
maximum range were we categorically return. They don’t, because the glassfi bre
(not tested by us) able to say that one hull absorbs and attenuates the incoming
being dependent refl ector was giving better signal and sops it up like a sponge, so little
primarily on height. results than another. or nothing refl ects back out again. ■
I-LENS • FIRDELL • ACTIVE-X • SEA-ME • ECHOMAX • TRI-LENS •
September 09 Sailing Today 59
ST149 Grp Radar Reflect_RTG.indd51 51 16/7/09 14:17:42
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