peter@
New Member
Any pointers on aligning a cylindrical radar reflector? My thought was that anything off vertical would reduce effective reflection from a ship-to-ship interrogation.
Aligning radar reflectors
- Thread starter peter@
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KellysEye
Well-Known Member
Ours is vertical, obviously that changes when you heel.
VicS
Well-Known Member
The performancel degrades if they are not vertical.
See the effects of varying the "elevation angle" on their performance in the QinetiQ investigation into radar reflector performance conducted for the MAIB as part of the investigation into the loss of the Ouzo
http://www.maib.gov.uk/cms_resources.cfm?file=/Radar reflectors report.pdf
See the effects of varying the "elevation angle" on their performance in the QinetiQ investigation into radar reflector performance conducted for the MAIB as part of the investigation into the loss of the Ouzo
http://www.maib.gov.uk/cms_resources.cfm?file=/Radar reflectors report.pdf
Robin
Well-Known Member
What kind of cylindrical reflector? If it is one of the French 'Mobri' types it doesn't matter really because they are about as useful as chocolate teapots. Firdell or Gillie Firth types should be mounted vertically.
l'escargot
Well-Known Member
First align the sending vessels radar to the vertical using a spirit level so that your reflector is aligned to exactly the same angle...
uxb
Well-Known Member
Don't waste your time and money....
Well, if you have an aluminium mast and any kind of engine. They will give a much bigger reflection than some stupid bit of tin bolted onto yer mast.
Simple Questions:
Is your aluminium mast got more surface area than the reflector you've bought?
Is your mast waving about up there going to line up to reflect a radar signal any better or worse than a ' radar reflector waving about up there?
How much beer could you buy for what you paid for said 'radar reflector?
And breathe................
Well, if you have an aluminium mast and any kind of engine. They will give a much bigger reflection than some stupid bit of tin bolted onto yer mast.
Simple Questions:
Is your aluminium mast got more surface area than the reflector you've bought?
Is your mast waving about up there going to line up to reflect a radar signal any better or worse than a ' radar reflector waving about up there?
How much beer could you buy for what you paid for said 'radar reflector?
And breathe................
peter@
New Member
mmm., looks like the best advice is to bin my cylindrical reflector; the performance of which is judged by MAIB as being so poor with a heel of only 1deg that "it would be better not fitted, lest be lulled into a false sense of security". I might ask the chandler for my money back.
Robin
Well-Known Member
Ah so it was a Mobri choccy teapot then!
sailorman
Well-Known Member
i have a cylindricial crap reflector at the top of the backstay. that makes me "street legal" all the time,very little windage or weight aloft, if & when if gets murkey i haul up a Firdell to the first spreaders
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Skysail
Well-Known Member
If they sold you a 4" tube type I would certainly ask for money back. But a Blipper / Echomax, or even a Octahedral, is way better than a curved mast (no reflecting surface at all) or engine (too close to the water line). But as the report says, you should fit one even if you should not rely on it.
VicS
Well-Known Member
Surface area is only one consideration and probably less important that the design of the reflector.
I have posted a link to the scientific tests carried out by QinetiQ on a number of popular reflectors.
Please post a link to the results of similar tests that you have carried out on the effectiveness of masts and engines as radar reflectors.
I suspect you have not performed such tests, cannot therefore post a link to any results and conclude, therefore, that your post above is worthless garbage.
.
sailorman
Well-Known Member
rob2
Well-Known Member
If you hoist a reflector up to the spreaders and let it swing it will not remain upright due to its inertia. I was wondering, if you take a shock cord down from the base to damp its motion, would it improve its performance? Has anyone tried this and found a workable length and thickness of shock cord?
Rob.
Rob.
l'escargot
Well-Known Member
If it is fixed then it will only remain upright when the boat is upright - probably very seldom on a sailing boat. Even if it is 10 to 20 degrees off vertical from the boat it is likely to be vertical to the sea just as often in any type of seaway. There could be an argument for letting it hang loose for a gimballed effect when the boat is heeled.
Any passive radar reflector is less effective in real life than it is under test conditions and is of limited value on small boats - they cannot be relied on to show up on another vessels radar and if they do there is no guarantee these days of anyone being there to see it!
bedouin
Well-Known Member
+1 - worse than garbage - it is dangerously misinformed nonsense.
While being far from perfect - radar reflectors work (apart from one or two nonsense ones) and any will be better than nothing
CreakyDecks
Well-Known Member
When NASA spent billions of dollars putting men on the moon they left small arrays of corner cube reflectors, just like of your bog standard radar reflector, to perform ranging measurements from earth. If there was a better way to reflect electromagnetic radiation I think they would have found it.
sailorman
Well-Known Member
bedouin
Well-Known Member
Yep - corners are as good as it gets provided that waves hit at a reasonable angle. The problem is that they are considerably less good with "off axis" waves, so the classic octahedral design has loads of "nulls" and is particularly bad when heeled (or hoist the wrong way)
uxb
Well-Known Member
You suspect wrong Oh Rude one.
There is no link to post as this was in the days before such things as internets. I kind of strongly suspect that radar waves haven't improved very much in the intervening years and that the quality of the person looking at a radar screen on anything large enough to cause concern has greatly diminished.
As for the yotties looking at their wee screens - 99% wouldn't know what they are seeing...
There are examples of the holy grail which you seek out there in intenet land if your not too lazy to look for them. Or to opinionated - I suspect the later.
Beadle
Well-Known Member
I have wondered why it was so difficult to make a "Stealth" aircraft when something designed to reflect radar signals - doesn't
