Radar Deflectors

Manos · 12 May 2007, 21:12

Although this does not come under electronics I thought that I should post it here.
Well what I discovered about these things.
IMHO they do nothing on a boat.

The experiment
I have put up a radar JRC radar on my boat. We scanned the RIB of a friend without a radar deflector and while on its side where it had no metal surfaces to deflect the radar beam the radar showed nothing. As soon as the rib showed the back and the metal of the engine deflected to the radar the RIB was shown clearly. We then mounted my radar deflector on my friends RIB. The deflector was mounted on the A frame. What we observed was the same as above.

Our conclusion if you do not have any type of metal on the side of the boat or if the radar deflector is mounted up high like on the yachts) it offerer no real assistance and ships or any other craft that have radar will not locate you unless on each of the sides of the boat there is a metal surface.

I'm not sure whether you agree or not, but I think that it will be helpful to hear some other views on this matter.

Poly · 12 May 2007, 21:48

Quote:

Originally Posted by Manos

Although this does not come under electronics I thought that I should post it here.
Well what I discovered about these things.
IMHO they do nothing on a boat.

The experiment
I have put up a radar JRC radar on my boat. We scanned the RIB of a friend without a radar deflector and while on its side where it had no metal surfaces to deflect the radar beam the radar showed nothing. As soon as the rib showed the back and the metal of the engine deflected to the radar the RIB was shown clearly. We then mounted my radar deflector on my friends RIB. The deflector was mounted on the A frame. What we observed was the same as above.

Our conclusion if you do not have any type of metal on the side of the boat or if the radar deflector is mounted up high like on the yachts) it offerer no real assistance and ships or any other craft that have radar will not locate you unless on each of the sides of the boat there is a metal surface.

I'm not sure whether you agree or not, but I think that it will be helpful to hear some other views on this matter.

Try here: http://rib.net/forum/showthread.php?t=19213&page=3 or search this site for radar reflector rather than deflector.

Manos · 12 May 2007, 21:53

Thank you for pointing this out

codprawn · 12 May 2007, 21:58

Manos if you have a RADAR deflector you could make a fortune - STEALTH RIBs!!!

Manos · 12 May 2007, 22:03

..... yes cod ..... why don't you take the mickey?

Deflector ... reflector ... I'm confused .... and I'm still sober

codprawn · 12 May 2007, 22:20

Quote:

Originally Posted by Manos

..... yes cod ..... why don't you take the mickey?

Deflector ... reflector ... I'm confused .... and I'm still sober

Who moi???

As if..........

Nos4r2 · 12 May 2007, 23:28

Quote:

Originally Posted by Manos

Deflector ... reflector ... I'm confused .... and I'm still sober

Thats what Gloucestershire does to you... Go sit on a tump for a whoile and clear yer 'ead

havener · 13 May 2007, 09:31

Quote:

Originally Posted by Manos

Although this does not come under electronics I thought that I should post it here.
Well what I discovered about these things.
IMHO they do nothing on a boat.

The experiment
I have put up a radar JRC radar on my boat. We scanned the RIB of a friend without a radar deflector and while on its side where it had no metal surfaces to deflect the radar beam the radar showed nothing. As soon as the rib showed the back and the metal of the engine deflected to the radar the RIB was shown clearly. We then mounted my radar deflector on my friends RIB. The deflector was mounted on the A frame. What we observed was the same as above.

Our conclusion if you do not have any type of metal on the side of the boat or if the radar deflector is mounted up high like on the yachts) it offerer no real assistance and ships or any other craft that have radar will not locate you unless on each of the sides of the boat there is a metal surface.

I'm not sure whether you agree or not, but I think that it will be helpful to hear some other views on this matter.

Perhaps you would like to inform the International Maritime Organisation, MCA, US Coastguard, Defence Evaluation & Research Agency, Nautical Institute, and the many others who have conducted benchmarked auditable trials and come to the opposite conclusion, before you start putting people off fitting important safety aids.

Simon

Poly · 13 May 2007, 09:55

Quote:

Originally Posted by havener

Perhaps you would like to inform the International Maritime Organisation, MCA, US Coastguard, Defence Evaluation & Research Agency, Nautical Institute, and the many others who have conducted benchmarked auditable trials and come to the opposite conclusion, before you start putting people off fitting important safety aids.

Simon

But they haven't come to different conclusions - read this: http://www.maib.gov.uk/cms_resources...s%20report.pdf

to paraphrase - "cheap radar reflectors are crap" or slightly more technically: low cost, entry level radar reflectors may not significantly increase radar cross section except at specific angles of approach...

jwalker · 13 May 2007, 11:31

And it's worse than may be apparent because the radar scanner is rotating and the reflector will need to be in its effective position just when the scanner is aligned with it. It will have to do this through a number of scans for the radar to show the reflector as a permanent target on the screen. Given the nature of the sea, it's not very likely. Having said all this, I find radar particularly useful because it frequently shows me targets before I see them visually so something must be reflecting effectively from these vessels.

havener · 13 May 2007, 15:48

Quote:

Originally Posted by Polwart

But they haven't come to different conclusions - read this: http://www.maib.gov.uk/cms_resources...s%20report.pdf

to paraphrase - "cheap radar reflectors are crap" or slightly more technically: low cost, entry level radar reflectors may not significantly increase radar cross section except at specific angles of approach...

And its those "specific angles of approach" that are the crucial bits.

There are some, as you say, entry level reflectors that are not much good - generally, the large the surface area of the angled panels, the better the reflector, especially when having to cope with heel from the top of a mast.

Detection may well not be significantly increased from, say, flybridge cruiser to rib, but certainly from a container vessel bridge to rib the differences become clearer. And it is the container vessel which is likely to pose the higher risk.

Don't forget too that commercial vessels will have both "s" and "x" band radars running, which very significantly aids close quarters range navigation.

In short, cheap radar to cheap reflector probably won't be brilliant, but decent reflector to £25k Raytheon kit will make a difference...