Which radar reflector

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The 'catch rain' position is as if you set the radar reflector on the ground in a stable position.

[/ QUOTE ] Thats how it is shown, it's just the angle from which the photo is taken that is confusing you!

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Vic, I'm not completely daft, I know that is how the photo was taken, it's just that about 50% of that type of reflector that I see on boats has the point uppermost as the owners obviously do NOT realise that the photo has been taken from slightly above, with the reflector sitting on the ground. /forums/images/graemlins/smile.gif
 
From the Qinetiq report, see the link on twisterowners post:

6 Recommendations
· Based on the results of this report it is recommended that yachtsmen always
fit a radar reflector that offers the largest RCS practicable for their vessel.
· The RCS of the radar reflector should have a minimum consistent RCS of 2m2.
· The Sea-Me is the recommended product if power is available
· If power is not available then the passive Large Tri-Lens reflector is
recommended
· The 4” tube reflector is not considered suitable due to its poor performance. It
is also recommended that the 2” tube reflector is not suitable since the
performance of this target will be even lower.
· It is recommended that poorly performing radar reflectors are not fitted as it
is possible that the user could be lulled into a false sense of security believing
that their chances of detection has been enhanced.

I would add my own observations, being; on a cross channel trip a few years ago, sailing in company with a boat using one of these, due to the fact hat we were all motoring on a flat sea and very bored I was observing my radar to practice judging distances. There were several boats close enough to be able to See a big white blob on the front of the mast (with binnies of course). These vessels produced a good splash on my RL70 screen, our friend by contrast could hardly been seen, at fact which I advised him of. This was long before the Qinetiq report.
 
I understand from previous articles and tests that the biggest radar return from a yacht is from the 'hole in the water' followed by the engine. In smooth seas and ideal conditions these will give a return that can be picked up easily. The situation changes totally when there is any sea, as neither the hole in the water nor the engine can be distinguished from wave scatter.

I have been on a yacht with no radar reflector at all, whose skipper called the coastguard to enquire whether we could be seen. At the time we were about three miles from their scanner. The response was that we had a strong signal. The sea was calm at the time (not later, but that's another story.)

On the question of lining the lockers with aluminium foil, one of the magazines tried this quite a few years ago. The results were pretty poor. From memory, this was because the faces struck by the radar signal did not necessarily reflect the signal back. The commercial designs are intended to do just that.
 
We have an Echomax ... seems to work well from what we have been told.

Interestingly, in the YM this month there was a picture of Andy O'Grady and Rod Heikel moored up together in the Cape Verdes, one with a tube reflector and one with a rain catcher one .... interesting!

Jonny
 
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Is that definitely correct about the elevation angle? it seems like an odd term to use for angle of heel, and also they have chosen an odd set of angles (1 deg, 5 degs etc. and none above 20 degs).

[/ QUOTE ] The angle of heel analogy was mine. From reading the description of the test it seems that the reflector was on a rig that simply raised it (and rotated it to get the different azimuth angles) The extent to which it could be raised was presumably limited by the rig but ultimately by the headroom in the anechoic chamber. Hence the rather small range of the elevation angle. It nevertheless comes back to being equivalent to heeling the rig those few degrees, although the actual angle was the angle by which the transmit and receive horns are "looking up" at the reflector.

It would have been nice if some other means of simulating the angle of heel had been used that could have got to much larger angles.

I hope I am right as I cannot see any other interpretation by if I am wrong then perhaps someone else will be able to explain.
 
“Based on the results of this report”

“I understand from previous articles and tests”

“The 4” tube reflector is not considered suitable due to its poor performance. It
is also recommended that the 2” tube reflector is not suitable since the
performance of this target will be even lower.” Will be even lower – really?

These reports are little better than bilgewater! (I’m dropping into Geordie now as I’m getting into a state) Get yersels oot there and do your ain tests. Only then will you know how good your set-up is.

When someone comes back and says that due to fitting this or that device I have improved my visibility by this amount will I believe. All the rest is conjecture.
 
Your probably right, I think Qinetiq are only a bunch of boy scouts playing around.

They know nothing, the MCA believe them, but hey! Who the hell are they to know anything?
 
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These reports are little better than bilgewater! (I’m dropping into Geordie now as I’m getting into a state) Get yersels oot there and do your ain tests. Only then will you know how good your set-up is.

When someone comes back and says that due to fitting this or that device I have improved my visibility by this amount will I believe. All the rest is conjecture.


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I am sorry The QinetiQ tests were done in a specialist facility by specialists in their field and under controlled laboratory conditions. They accurately compare the performances of the chosen reflectors.

What you cannot do is "get out there" and validly perform your own tests because you will have no control over many variables that can influence the results. Although you may think you are carrying out valid tests for yourself it is this lack of control that in fact invalidates your observations.

The QuinetiQ report is very far from bilge water. It is just what it set out to be. An accurate comparison of several reflectors under controlled conditions. The bilge water would be the results you obtain by getting out there and doing your own tests.

It is a reasonable deduction that the performance of the tiny 2" tubular reflector will be poorer than that of a 4" one of the same design and the performance of that was so poor that it would be difficult to justify the cost of testing the smaller one.
 
From memory, the smaller trilens did indeed give a less intense signal but it gave a more consistent, reliable response with heel angle and with angle of observation than most, if not all of the competition. With automated radar plotting systems having as a target defining criteria the need for a reflection on each of several passes the consistency of response is a key asset for a reflector.
 
Reinforcing the other comments here - echomax seem to be the best and if using the octahedral it is essential to use it in "catch rain" position - regardless of where the holes are drilled
 
Well Vic, Qenetiq might just as well have concluded that the 4" showed no improvement on the 2". But what we know is that they don't know, they assume, as they didn't test.

My unscientific tests show I'm visible to Yacht radar at 1.5M in good conditions. That is more valuable to me than a Qenetiq supposition.

I stick by my guns. Carry out your own tests before parting with your money.
 
Echomax for us. We have the EM230BR, which gets good reviews. Supposedly same performance as the EM230 but a bit smaller.

Incidentally I think I read somewhere that the US navy now use Echomax 230 reflectors on there subs when running on surface. also in us by the UK military, according to their website.

Oops, just re-read teir website and it's the 305 the US subs use.
 
I agree re. the tri-lens type.
Came out better than Firdell and EchoMax in tests over the last couple of years IIRC.
Well that's why I bought one instead of an EchoMax, at the time. /forums/images/graemlins/cool.gif
 
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they assume

[/ QUOTE ] logical deduction. [ QUOTE ]
My unscientific tests

[/ QUOTE ] are not worth a light! [ QUOTE ]
I stick by my guns

[/ QUOTE ] If you think that has any relevance [ QUOTE ]
Carry out your own tests

[/ QUOTE ] Why bother to try, unless you have the facilities, the equipment and the scientific expertise to do so properly.

However I am sure we are now all the better for you expert and well informed input into the discussion.
 
Vic, instead of questioning my findings, why not carry out your own tests?

I'd like to know if your findings support my own.

Knowledge is better than belief.
 
If you are comforted by your boat being seen on radar at 1.5nm in "good conditions" then you are right to not worry about objective, quantitative tests carried out with state of the art equipment in an anechoic chamber. However, and admittedly not on a saily boat radar, I have seen seagulls at a considerably greater range and they were not, as far as I was aware, carrying reflectors.
 
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