Which radar reflector

Fascadale

Fascadale

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I have one of these, long tube type, (about 24 X 4 inches) mounted near the top of my backstay
560006.jpg


After the Ouzo initiated research I am left wondering if that type of reflector is much use.

I am thinking of carrying one of these, traditional type, to be hoisted to the crosstrees at night or in bad vis. (as well as the long tube type on the back stay)
550003.jpg



Would one of these,
echomax type (mounted near the masthead) be the answer ? ( better than the long tube and the traditional combined)
560025.jpg


Unfortunately I cannot afford a see-me type active system

What do the panel think?
 
I have had an octahedral to hoist in bad visibility since I bought the boat. A couple of years ago I was chatting to a friend who is skipper on a small coaster type of boat, and he suggested that most boats navigate and avoid small boats using radar, regardless of visibility. A grp (or wooden) sailing yacht is nearly invisible on some points of sailing, so I have now fitted an Echomax. It may not give as good a return as the 18" octahedral, but it is always up there and doesn't bang and clatter around the backstays when we're sailing. It isn't as "bright" as a Seame either, but it doesn't drain the battery, works when the battery has gone flat and can't be switched off.
 
The tube thing is useless, it does nothing to improving your visability as already reported in various published tests.

Echomax would be my choice.
 
can someone please explain what is meant by the 'elevation' angle mentioned in the report, and also the 'azimuth angle'? the elevation angle seems to be important, but it doesn't say what it is!
 
Has anyone ever tried lining the insides of their lockers with aluminium foil? What does the panel think?

Nicholas Hill
 
The reflectors were fixed in the upright position (or catch rain for the octahedrals). The elevation angle is the angle to the horizontal plane at which measurements were made. It would be the same as the angle of heel if the measuring equipment had been fixed and the reflector tilted as it would be on the mast of a yacht heeling over.

The azimuth angle is the angle measured around the reflector from the starting point in the horizontal plane. So you could read that as the compass bearing of the measuring equipment from the reflector but east or west of north rather than in the usual 360 degree notation.

I hope!
 
[ QUOTE ]
Viking is another option to consider - a much more reliable signal when heeled than any of the others under test as I recall

[/ QUOTE ] You may be right but recalled from what comparable independent tests?
 
Bear in mind that the octohedral reflector should be mounted in the 'catch rain' position, and not as shown in your photograph.

The 'catch rain' position is as if you set the radar reflector on the ground in a stable position.
 
[ QUOTE ]
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!
 
[ QUOTE ]
Has anyone ever tried lining the insides of their lockers with aluminium foil? What does the panel think?

[/ QUOTE ] Makes the inside of the lockers look pretty.

Too low and will only reflect strongly at very specific angles. A graph showing the variation of RCS with azimuth angle will rise and fall like mountain ranges and deep valleys I would think. Once heeled vertical surfaces will be absolutely useless so a simple flat sided locker will show big mountain peaks at 0 ±90 and 180 azimuth angle and 0 elevation with virtually nothing in between and virtually nothing at other elevation angles.

The ideal reflector would give a good steady RCS at all azimuth angles and be the same at all elevations. (The POLARef 11 included in the QinetiQ report for comparision)
 
I take most of your points, but on the other hand, presumably a steel hulled boat shows up well, and a lot of what you say will also apply to them. Perhaps boat designers should incorporate an aluminum foil layer behing the fibreglass ...
 
Actually, any flat surface perpendicular to the radar waves is a good reflector, I have seen a yacht go from invisible to a good blip at about two miles off, when she gybed and presented the sail square on to us. Fishing boats are best, they are all flat steel plates and angles, modern grp and wooden yachts are worst, all curves. Lining a curved grp hull with tin foil might improve the signature, but a series of intersecting flat metal plates is going to be better. Like ... er ... a radar reflector! /forums/images/graemlins/smile.gif
 
I have what some skippers here call the 'useless tube'.

In tests carried out with cooperation from other yachts I am assured I can clearly be seen on yacht radars at 1.5M distant.

The boat is grp and both test were carried out in good conditions. Ideally I should have removed the tube and asked for a retest (but the thing is pemanantly set at the spreaders. So I don't know if the radars were picking up the boat or the reflector or some combination of the two).

I would advise caution before spending more dosh. Get out there and carry out your own tests. Yotties are happy to cooperate as it adds to their knowledge too.
 
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). Is it not something to do with the angle subtended by the boat relative to the emitting radar?? although that also seems wrong as the angles would presumably all be small? /forums/images/graemlins/confused.gif
 
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