Which radar reflector

[ QUOTE ]
Vic, instead of questioning my findings, why not carry out your own tests?


[/ QUOTE ] Because I do not have the equipment, the facilities or the technical expertise to carry out tests of this nature as you presumably do.

If you publish the details of your tests, explaining how all the variables were controlled "out there" we will all able to judge them on their true merits. In the meantime I'll put my faith in a group of investigators , who were presumably, until the Government donated most if not all such facilities to the private sector, MOD research scientists
 
Teredo

What about my own observations, nothing to do with Qitetiq, but tests carried out much the same way as you describe. From an earlier post in this thread, when I refer to 'one of these' I mean a 2 or 4 inch tube:

"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 would suspect any radar image anyone was getting from your boat was most likely from the mast, a good reflector, at the correct angle.
 
'I would suspect any radar image anyone was getting from your boat was most likely from the mast, a good reflector, at the correct angle.'

Galadriel, you could be right, as my test did not allow for a test with and then without the reflector.

Incidentally, I was amazed at seeing a ship radar pick up a swimming herring gull. And I was assured by a ferry skipper that his radar can see yachts clearly when crossing the North Sea.

AIS is perhaps the future?
 
yes i would be realy happy for that tanker doing 25kts to spot me on his radar at 1.5mile - all of 3.6min before he runs me down
 
be unhappy nick. Tankers don't do 25kn.

Remember also that I was seen by a 10m yot at 1.5M. The visibility range might have been much more than that. I would also expect tanker radar to be better than yot radar. Wouldn't you?
 
Teredo

It would be really helpful if you could provide us with details of your "test" as all you have given us so far is an observation that another boats radar could pick you up. As several posts have noted, yachts without radar reflectors can be observed because the boat itself reflects a signal. The test (such as the Qinetic tests) is whether the Radar Reflector itself shows up, independent of whether it is fitted to a boat. The tests therefore record the relative effectiveness of the device itself compared with other devices tested in the same way. Your "test" only tells us that one boat's radar can pick up your boat! So What! We would still be in the caves if we relied on that kind of "test" to improve our knowledge of the world around us!
 
'Your "test" only tells us that one boat's radar can pick up your boat! So What!'

The purpose of my tests, 2 so far, was to find out if I can be seen on radar. It is surely THE essential question for us all, is it not?

You've nothing to lose. It'll cost you nothing. I can't understand your resistance to do the same?
 
Not quite!

For my part the anecdotal evidence presented here is about what I expect when there is unpalatable factual data mixed with a liberal helping of opinion and hearsay. The requirement is to determine if a radar reflector works and if it’s worth fitting, not if radar can see a seagull or a yacht or a lobster pot flag etc.. Concentrating on the actual requirement needs something like the work done by the MCA following the Ouzo incident. The facts of that test and others cited here on the forum speak for themselves; the inescapable conclusion is that for most of the time most passive reflectors are invisible to radar and the performance of the few that are visible some of the time is disappointing.

Let’s not forget that these results were obtained in artificial conditions with perfectly calibrated radar. AND they only tested the radar reflecting capability of the radar reflector, not the hole in the water, the outboard on the transom, the hull or mast as these elements are so variable from one craft to another that there is no way a useful conclusion on the performance of the radar reflector could be established. Furthermore this disappointing performance will be expected to degrade in heavy weather (i.e. less than perfect conditions) in practical terms THEY SIMPLY DON’T WORK.

The actual situation “in the field” only gets worse:

So we must ask ourselves what do we know about the condition of the radar sets on the VLCC on the horizon? The answer is we know nothing, so apart from not knowing if there is a crew looking at the display we have no way of knowing if their radar is correctly calibrated and working if they are. We have no way of guaranteeing that we can be seen with or without a reflector. BUT that is a whole can of worms debate, which can never be answered conclusively except in retrospect, encounter by encounter.

For me the fitting of a passive reflector is a waste of time and money – but the law “which must be obeyed” insists that I carry one so I comply under duress citing the MCA tests and others mentioned above as to why passive reflectors are a waste of every resource you can think of.

AIS is heading for the same dismal outcome. The commercial shipping that does us the most harm will not be looking for Class B transponder information; they will subjectively filtering it out of their displays again making us invisible.

There is a pattern here and we must look to the Italian proposals for the rewrite of the collision regulations to understand it. If “we” are demonstrably invisible to shipping then it makes sense that “we” have the responsibility to keep out of the way of the “blind ships” – which in a nutshell is the Italian proposal.

The two items I have described above are compelling evidence for the adoption of the Italian proposal. Please don’t shoot the messenger and NO I am not saying I agree with it.
 
I made this comment on one of the other radar postings.

I was once involved with DB Research in a sea trial examining sea clutter and leisure vessels. When talking with the MD (Bill Mullarchy), he made some interesting comments that his research had shown that many a boat's return was due to the hole they made in the water and not the hull, water on the sails or their radar reflectors.

Given this, a hole is more obvious in a calm sea, making a yacht potentially more difficult to see in choppy conditions.

Another interesting point to make is that on this particular test, one of the yachts involved was only visible on radar when stern to, and invisible when broadside!

Makes you think, doesn't it.

From the pic on the website above, you can the see the many radars used in their research.

DB Research writes software which they licence to radar manufacturers tio improve their performance. Raymarine is one of them. They also make commercial ships black boxes which were invaluable in determining the outcome of the Ouzo incident.
 
Sorry if its been said before, I dont often get a chance to see the internet at the moment (KSA is not known for connectivity) but I think the debate is a very worthy one.

Over the years I have posted many times about radar on this forum. To me its clear; small boat radar is a very good AID to collision avoidance but it very certainly doesnt see everything. And in general terms yachts with reflectors dont show up any better than those without and power boats head on are stealth technology painted white. My current setup is raymarine prior to that JRC, furuno, apeco - honestly there's nothing to choose between them - they all have "blind days" and you cannot depend on them to show all targets when it's rough - but they are (to me) better than nothing. However, the current offering RL70 often fails to pickup the speedferry out of Dover; you would think that thing would offer a consistent return! - we hear it and see it long before the radar sees it. And yet the RL70 sees every conventional ferry.

Clearly something needs to be done about the passive reflectors on the market - the phrase "gives the user a false sense of security" fits well with the majority of them all the time and all of them in the sort of conditions where they are needed most, and the same phrase can equally be applied to AIS and leisure RADAR in fact all leisure navigational electronics. The whole lot is best described as "expensive gadgets that appear to work". The whole electronics industry has an obligation to its customers to declare the actual performance of their kit so users can decide if on balance if its worth fitting. For much of it much of the time the answer is no its not.
 
Teredo

No resistance to your "test" at all. Only resistance is to generalisation from one (now two) observations!. Your "result" only applies to Your boat in That Situation at That Time, and as observed by one operator of one radar.

As many of the other posts have explained there are so many factors that affect whether a boat shows up on radar, that it is very difficult to generalise.

The real "Tests" such as Qinetic are designed to find out whether radar reflectors do what they claim - that is show up on radar under a variety of conditions that simulate the way that yachts operate. They are an aid to the decision about firstly whether to fit one at all, or secondly which to choose.

When attempts have been made to test out their effectiveness in operating conditions, rather than the lab, the results are usually inconclusive BECAUSE of all the other factors which cannot be controlled.

Marsupial

The situations with AIS B is, I think, different. Technically, except for the possibility that the system is overloaded your signal will always go out. Whether it is effective is a function of the recipient taking note. This is of course true of any radar - if nobody is looking, you will not be seen, no matter how many reflectors you have up!

There is quite a good summary on AIS including the value of Class B in this month's PBO
 
'AIS is heading for the same dismal outcome'

Don't be so pessimistic Mr Marsupial, If I have an AIS I will have course, speed and name of a particular vessel in my vicinity. (I accept that he won't see my AIS details) But I can vhf him if nec and we will decide who's gonna do what.

I would hope that my AIS will integrate with my future plotter.
 
Tranona, if you are happy to live with laboratory findings and not carry out your field tests with your own particular set-up then ok.

There, I've done my best to persuade you and failed. That's the end of story for me.

Safe sailing matey.
 
No not pessimistic but realistic. And you have realised that the onus is on YOU to be aware of a situation NOT "HIM" which is a bit perverse. (I have often tried and failed to raise large vessels on VHF or conversation has been in Chinese or something oriental and therefore not effective) I accept that the AIS is a valuable AID but it’s not the whole answer as I explained previously.

Returning to the overall picture of visibility, devices and the Italian proposal, the expectation is that you will be the only agent responsible for you and that furthermore the leisure craft is NEVER the stand on vessel. Sadly all the above in this thread supports that view and if adopted large vessels can run down leisure craft because a) they can claim that did not see them (they were not looking for them) they are invisible and b) they are the stand on vessel and the leisure craft should have stayed at a safe distance as the give way vessel.

If the leisure craft community can lobby manufacturers to provide equipment that does ensure that leisure craft can be detected or that leisure craft owners adopt the technologies that are available then the proposal is harder to argue for. Personally I want a more powerful seame that makes me look like an aircraft carrier on HIS display.

Can somebody tell me WHY many of the contributors on this forum are so anti the seame because it uses electricity? and yet at the same time are investigating how to attach a laptop to a boat battery or install another wide screen plotter/entertainment system? It beggars belief. The seame will be pinging long after the plotter has given up and the laptop on a boat? Please . . . I have seen an Volvo 2002 bouncing around the bottom of a boat having sheared its mountings during a gale in the north sea – laptops weren’t invented then but I don’t think the hard disk would have survived the “wave event” that detached the engine!

(Sorry if this has been said before on the forum but this is David in KSA signing off for another week)

If anyone is near a Pub have a beer and think of us in the land of the fruit juice!
 
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