Radar Reflectors

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AndCur

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Folks

How high up the mast should I mount a tube type radar reflector. I currently have it on the backstay about 8ft above deck level. Is ok or would it be better further up the mast.

As all ways thanks for the reply's

Andrew

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I presume by 'tube' type you mean the ones that are about 2"/3" in diameter? If so it probably doesn't matter where you mount them as several tests over the years have indicated that they are more or less useless!

<hr width=100% size=1>dickh
I'd rather be sailing... :-) /forums/images/icons/smile.gif
 
Most tests that I have seen suggest that they're all pretty useless & the best thing you could do is to tow the QE2 Behind you!

Martin

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I have two ... A diamond and a tube type reflector. One stays with my new yacht and one goes with the old one

I'm guessing I should keep the diamond reflector then?

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PBO did some very interesting tests on radar reflectors a couple of years ago, might be worth trying to find out if they archived it online......keith

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IMHO the only three passive radar reflectors worth considering are The Echomax, the Firdell and an Octohedral design (there are a number of proprietory versions of the basic octohedron).

The best performance of these designs is roughly similar, and they all have "nulls" in their performance. Of these the octohedron is the worst, followed by the firdell, with the echomax being the best.

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In-depth info <A target="_blank" HREF=http://www.ussailing.org/safety/Studies/radar_reflector_test.htm>here</A>. I've got one octahedral that I hang off a spreader in the double catch rain position and have been considering a second octahedral on the opposite spreader in the single catch rain attitude as an attempt to have them cover some of each other's nulls. (Can't believe I just wrote that) Anybody else got any thoughts on the matter.
Dave

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by machurley22 on 29/10/2004 20:21 (server time).</FONT></P>
 
"in the double rain catch position" and the "single catch rain attitude"

I'm assuming these are contorsional restraints for better sex listed in the Kama Sutra....Yes?

<hr width=100% size=1><A target="_blank" HREF=http://colvicownersclub.mysite.wanadoo-members.co.uk>http://colvicownersclub.mysite.wanadoo-members.co.uk</A>
 
Re: Radar Reflectors - rather long

ISAF Special Regulations for Category 2 Offshore Sailing Races (January 2004 - December 2005) require that a boat be equipped with :
"4.10 Radar Reflector
4.10.1 A passive Radar Reflector (that is, a Radar Reflector without any power) shall be provided (see 4.10.3.3)
4.10.2 Attention is drawn to ISO8729. If a radar reflector is octahedral it must have a minimum diagonal measurement of 456 mm (18in), or if not octahedral must have a documented RCS (radar cross-section) of not less than 10 m2. The minimum effective height above water is 4.0 m (13 ft).
4.10.3.1 The passive and active devices referred to in these notes and in 4.10.1 and 4.10.2 above are primarily intended for use in the X (9GHz) band
4.10.3.2 The most effective radar response from a yacht may be provided by an RTE (Radar Target Enhancer) which may be on board in addition to the required passive reflector.An RTE should conform to Recommendation ITU-R 1176. An RTE is strongly recommended.
4.10.3.3 The display of a passive reflector or the operation of an RTE is for the person in charge to decide according to prevailing conditions.
4.10.3.4 Attention is drawn to a new performance standard for radar reflectors in draft at IMO ref Nav 49/19 Annex 12 expected to be adopted during 2004 intended to ensure a better and more consistent level of performance than that achieved by ISO 8729 or a 456mm (18") octahedral reflector. A passive reflector conforming to the new standard may be in the form of a cylinder of not more than weight 5kg, height 750mm and diameter 300mm.
4.10.3.5 S (3GHz) band radar is often used by ships to complement X (9GHz) band radar. On S (3GHz) band a conventional reflector or RTE offers about 1/10 the response obtained on the X (9GHz) band.
4.10.3.6 Yachts are reminded that no reflector, active or passive, is a guarantee of detection or tracking by a vessel using radar."
It might be significant to note that of the 22 boats that I scrutineered for the Rolex Middlesea Race 2004 NOT ONE could produce documented evidence of an effective reflective area of 10 square metres. Only one offered an inflatable monster complying to the dimensions mentioned in 4.10.3.4. They ALL had octahedrals. If you are not familiar with the Rolex Middlesea Race, ( www.rolexmiddlesearace.com ) it is the most spectacular race in the Mediterranean, is 607 miles long and attracts such boats as Alfa Romeo, Black Dragon, Damiani Our Dream, Innovation, and so on. For the duration of the race these boats DO keep a tiny tube toy in their rigging; they are still conforming with the main requirements of 4.10.
However, bearing in mind the caution that is contained within 4.10.3.6 it is well to remember that these are B-I-G beasts with typical crews of 20-24 professionals!
For boats of 'my' size I shall hang on to my old octahedral as a backup for my Mark I eyeball. If the active radar target enhancers ever float down to affordable prices then, yes, I would be tempted.
This notwithstanding, I would still bear in mind that I would still have absolutely no guarantee that there is somebody on the bridge of an approaching vessel who is diligently watching a radar screen and is not dreaming of his partner across the dark ocean.
Sorry if this was too long but I sincerely hope that you get the picture.
Fair Winds!

<hr width=100% size=1>Wally
 
Re: Radar Reflectors - rather long

Think Wally hit the nail on the head,... Ultimately if the plonker on the other vessel isn't looking at his radar or as has been documented elsewhere ,its switched off, then all our efforts are for naught!!!........keith

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One point worth considering when siting the reflector up the back stay, is that, depending on the layout of the rig, a slacked-off topping lift may have an irritating tendancy to foul round it.

Mick

<hr width=100% size=1>. . . . . . .<A target="_blank" HREF=http://www.marinersboatyard.co.uk>boatyard</A>
 
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