MAIB Report

[willmunro]

I think its about time everybody had a good think about just how visible and vunerable we are out there. With the huge increase in traffic in recent years a good radar signature is essential. I'm looking into Active Radar Reflectors at the moment and feel they are definitley worth the investment.
Any thoughts would be appreciated!

 

[JREdginton]

Been an ongoing thread in the Jester forum...

http://www.ybw.com/forums/showflat.php/Cat/0/Number/1386089/an/0/page/0#1386089

A couple of items listed.

 

[Bav34]

I am both concerned and confused by the part of the report suggesting that the yacht was not picked up on the ferries radar. Part of the report says that a similar yacht WITHOUT a radar reflector was picked up by VTS in Southampton during part of the investigation as far away as Bembridge.

Last weekend we motored around the Isle of Widget in company with some friends who were at times ahead and other times behind us. The ONLY time we 'lost' them on radar was when they were directly behind us .... scanner is mast mounted.

We could see EVERY other craft regardless of size.

The only difference then was that our sea conditions were flat calm and the night of the accident I think that I read that there was a F5 blowing plus attendant swell.

If this means that I am 'invisible' in a F5 then it's time to give up night sailing !!!

 

[Bergman]

I take a very sceptical view on all of this.

Clearly there is an issue, but what

40 years ago radars were capable of tracking tiny objects at great heights.

Since 1940 both air and sea defence has depended upon radar.

People routinely relate stories of seeing good signals from birds in flight on basic "amateur" quality radars.

In the Ouzo case radar tracks a vessel with sufficient accuracy and with a sufficiently robust output that the CPS is prepared to put it to a jury as evidence, not only in the case of Ouzo but a second time in the simulation run by the MCA.

We are then asked to believe that 2 high quality "professional" radars on a modern highly regulated and inspected ferry fail to detect the same yacht which must have been within range for at least 30 minutes, and with a range of from several miles to a few feet.

I find it difficult to accept that there is a technological explanation for this.

Considering the actions and perhaps more significant the attitudes displayed during and after the event I would suggest that a failure of the human element is a more probable explanation of the incident.

My personal view is that radar reflectors are little more than decoration, evidenced by the fact that VTS radar tracked the yacht that simulated the Ouzo but without a reflector with equal facility to the tracking of the Ouzo itself with a reflector.

Technically an active transponder would most certainly create a much stronger return. Whether anyone would see it and act correctly on what is on the screen is another matter

 

[tome]

I think you need to understand a bit more about radar with respect. The key word is clutter

You don't get any clutter when tracking an open sky target

The situation is very different at sea, where you are trying to track a target sitting on a reflective plane. On a big ship, the angle of interest is mostly looking ahead for dangerous targets and radar is very good for this

Tracking small targets such as us calls for much more skill and is fraught with difficulties. To start with, we are below the radar height and sitting on the reflective plane. Flat seas and attentive operator, they can see pick us up easily

As the waves build, their faces start to reflect the radar back to the ship providing many returns from below amongst which our boats will be lost. This is clutter, and by F5 head-sea such as the ferry was experiencing he didn't have a hope in hell of picking out a 25 foot boat stern-too. In fact, the OOW will have turned up the anti-clutter by now so he can make out real targets agsinst the false wave returns

If you read the report carefully you'll see that MAIB recommends that bridge crew turn back the anti-clutter manually from time to time to give small targets a chance to appear. However, my experience of doing this for real with both X and S band is that you'd be lucky to spot a small vessel

One positive point which no one seems to have picked up in the report. Qinetiq Funtington are going to conduct some tests on our radar reflectors, and I for one will be very interested in the outcome

 

[Norman_E]

I am a sceptic too. I suspect the radar "saw" the boat, but the operator did not. What really upsets me is the thought that a lookout on a ship can see a yacht fairly close ahead, and not check to see that it has been safely passed. I have not read the full report through lack of time, but the above was clearly implied by the press report I saw.

 

[JREdginton]

The MAIB report did run the PoB 'black box' and confirm that neither radar detected the yacht (if I have read it right) which is scary! It also states that the OOW did not follow procedure/guidelines and switch to manual clutter supression from time to time, the human element creeping in again.

I was also surprised to see that while the PoB must carry an AIS class A transmitter (commercial, over 300tonnes) she is not yet bound to recieve AIS info on her radar dispalys? Not that it would have help the crew in this situation but I am probably not alone in looking at Class B transmitters for added security.

 

[tome]

With all due respect to your sceptism...

The VDR was examined by MAIB including the radar recordings. No trace of Ouzo was recorded by PoB on either radar

Best not to rely on what we read in the tabloids, eh?

 

[FullCircle]

This may be a bit heathen, but here it is anyway.

Yachting in a small boat at sea has its risks. I consider these risks to be the equivalent of motorcycling, in that it does not matter a stuff what the rules say, the object is not to get hit by the bloke who hasn't seen you.

Therefore, the 'aids' to missing you are just that - aids. They do not guarantee to steer the ship/car out of your path once they have detected you, and I doubt they will in my short time left.
I know its a tragedy, but its a risk assessed and taken, and I would shuffle off the mortal coil knowing I would not change things if it happened to me. In fact it nearly did, in the Thames. I fired a mini flare at the bridge windows. They turned left just in time to miss us by not more than 30 feet. My risk? Dead engine on a windless day.
Same trip, at 2am, family phoned North Foreland and asked if we could be seen. Answer? No, yet we were less than 3 miles from North Foreland in a flat calm with me octahedral jauntily hanging on the backstay.

Have only had radar for last 2 seasons and really appreciate its qualities, but its only an aid to avoiding bigger stuff than me, and does not make me venture into TSSes in thick fog or other adverse conditions just for the hell of it.

Please wrap up the active SeaMe thing and send it in the post, I would appreciate that, but its not armour.

 

[Bergman]

Firstly thanks for your explanation.

You are quite right I would very much like to understand more about radar - its certainly not my field of expertise.

Perhaps you can clarify further if you have the time.

I follow your description of how clutter can mask a return from a small boat which is low down, particularly below the height of the radar. It does pose to me a few questions.

Why is the VTS radar seemingly able to overcome this problem?

I believed that clutter was mostly a short range effect which had a much lesser effect on targets at longer range - am I wrong in this belief?

Assuming the radar reflector is sited at a reasonable height - why does this not overcome the clutter, at least to some extent. I would expect a target - say - 20 ft up a mast would be discernable from 4-5 ft waves. Assuming that the reflector works.

Why cannot some form of doppler be used to separate lots and lots of similar reflections travelling in roughly the same direction from a small number of "hard" reflections going in a different direction.

In the case of Ouzo the ferry followed a very similar course from shortly after leaving Ptsmth until the collision. During that time I would have expected at least some responses from the yacht would have been received, is it not possible to "store" these intermittent responses and recognises a pattern to create an alarm.

I guess some/all of these things are perhaps impractical or even impossible, but when considering the reliance placed upon radar to have such a gaping hole in its capability seems to bring the whole system into question. Particularly when you consider that we are looking at the top end of the market with the PofB.

I too will be very interested in the performance of radar reflectors.

 

[tome]

Very happy to respond as SWMBO is away tonight and I find the MAIB report quite fascinating
[ QUOTE ]
Why is the VTS radar seemingly able to overcome this problem?

[/ QUOTE ]

VTS were tracking them in the smooth waters before they disapeared around the high land where they were obscured by IOW land mass. It was at about this time that they would have encountered the bigger seas and even if VTS were still able to 'see' them they would have been lost to sea clutter to them also

[ QUOTE ]
I believed that clutter was mostly a short range effect which had a much lesser effect on targets at longer range - am I wrong in this belief?

[/ QUOTE ]

Yes, quite wrong if the target is low as radar cannot discriminate

[ QUOTE ]
Assuming the radar reflector is sited at a reasonable height - why does this not overcome the clutter, at least to some extent. I would expect a target - say - 20 ft up a mast would be discernable from 4-5 ft waves. Assuming that the reflector works

[/ QUOTE ]

Good question - I look forward to the Qinetiq report which I think will be enligtening

The other questions (Doppler etc) would take a lengthy explanation so excuse my being rude in leaving them aside

Cheers
Tom

 

[Bergman]

"The other questions (Doppler etc) would take a lengthy explanation so excuse my being rude in leaving them aside"

OK

I'll let you off on this occasion.

By the bye

My first experience with radar was sitting on a mooring in the River Orwell.

I could see the Orwell Bridge

I could see the buoys down the river

I could see both banks

But could I see the damned great ferry running up the river - could I hell as like.

No idea why

Hey Ho

Thanks for the info

G'nite

 

[Sinbad2222]

Tome - I would be interested to know if you have read this US assessment of various yacht radar reflectors.
http://www.ussailing.org/safety/Studies/radar_reflector_3.htm
Maybe Qinetiq should save themselves the effort?

 

[tome]

Yes I've read it, but hoping Qinetiq will cover a better UK range of reflectors Also, Funtington know their onions when it comes to real tests IMO

 

[bilbobaggins]

Bergman,

There are lots of forumeers with trained radar technical backgrounds, and many skilled and trained operators. Much of what you ask seems reasonable, but is impracticably expensive to install and to maintain.

Doppler radar - measuring the apparent frequency shift between tx. and rx. energy caused by relative motion between emitter and target - has long been used in military air defence environments. It is much more expensive to maintain as a system - including purchase and installation, service and maintenance, and training and recurrent validation of operators - than 'vanilla' systems, and much more difficult to interpret. How useful would it be for a vessel, stopped, to find that the coastline and all other fixed objects had disappeared?

In lumpy sea conditions, breaking wave fronts reflect much more RF energy than small sailing boats and their corner reflectors. The intermittent return from your ( my) little boat will be obscured at best among the many larger 'paints' from seas - and internally suppressed at worst by the kit's sea clutter software, for it appears to that software to be just one of very many small waves.

It is probable that the Radar Equivalent Echoing Area of yer standard yottie 'corner reflector' is rather less than the yot's wet sails...... speak to any of the 'top end' radar reflector inventors at the boat shows, and examine their complex but convincing proof.

The MCA's free leaflet tells us of sensible but now mandatory requirements, which some of us have been ignoring. SOLAS V Regs, for example, call for us all to have radar reflectors of REEA ( see above ) of 2.5 square metres or more.

[ QUOTE ]
Regulation 19 para.2.1.7 requires radar reflectors to be carried, where practicable, by ships under 150 GT. For UK-flagged this includes pleasure vessels.

The following notes gives further guidance on the choice of a radar reflector for small vessels....

2.) An important parameter of a radar reflector is it's echoing area, or equivalent radar cross-section, as this determines the amount of the radar energy which is reflected back. Reflectors to the above standards have a maximum echoing area of at least 10 m² with a minimum echoing area of at least 2.5 m² over 240° of azimuth. Orientation of the reflector must follow manufacturers recommendations if it is to be effective

* The Performance Standards are currently under review ( I'll bet! )

[/ QUOTE ]

The inference from that is that Coded Boats still using 'el cheapo' corner reflectors are illegal - in that they are in breach of the IMO and UK Regulations.

Marine radar works at 'centimetric wavelengths'. The human eye is at least 5 Orders of Magnitude more sensitive and discriminating, auto-compensating for gain and contrast in respect of illumination changes, stereoscopic, polychromatic, and coupled to arguably the fastest organic CPU on the face of the planet with huge working memory, storage and heuristic interpretation capabilities. On most small craft there are usually at least two of these complex sensor systems systems operating in the visible light and near IR spectrum, and more often 4 or 6.

Many operators fail to use these superbly-effective devices as the designer intended, preferring the scant results from a vastly inferior design used intermittently.

"See and be seen...."

There really is no substitute for the real thing.....

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[johnphilip]

I have just spent a very sobering time reading the report and it shows many ways in which both leisure and ship sailors can be led into this situation. Major future cosiderations include:-
Crotch straps on lifejackets. Can we get the valise packed liferaft out of a shallow cockpit locker quickly enough? Active radar reflectors, AIS B, Epirbs.
Unlikely to have happened with the experienced Ouso crew but I admit to being caught out by the situation when a ship approaches from over your quarter while you are staring ahead. Other among you will agree that the ship coming from behind is the most difficult to judge which way to go to keep clear. With the ship gradually changing course a few minutes before the incident it must have been near impossible to judge.
How many of us in the very seconds between normal traffic situation changing to sudden collision danger will have gathered our wits to make an effective call on the VHF .
Years ago (pre DSC ) Idid try to call a ship approaching us from astern near the Twinn buoy off Belgium. The result was about 4 different responses I could not sort out.

 

[Bergman]

Agree about the Mk1 eyeball. That too seems to have been working at somewhat less than optimum on that night.

But to get back to radar.

Why would the MAIB recommend turning down the clutter control periodically?

I can only assume that this would would enable a skilled operator to see things that would be otherwise hidden in part by the clutter but also more significantly by the anti clutter system. If the "useful" signal was completely, totally lost in clutter than there would be no point in periodically turning back the control.

I do not know but I assume that the recording taken by the "black box" was effectively a recording of what was seen on the screen - which would not show anything that could be seen with anti-clutter control removed - cos it wasn't!

The recommendation must imply that some signal or reflection from a small and indistict target is going to be received among the clutter. Assuming this is the case then making the reflection clear and visisble becomes a question of signal processing.

Stepping back many years, you may remember a programme on TV called Tomorrow's World. It was hosted by Raymond Baxter.

I clearly remember seeing a demonstration of a "new" radar. The radar scanned an aircraft and effectively "drew" a picture of the thing on screen. Although limited in resolution it was clearly a twin engined aircraft (in fact it was a Canberra). If signal processing was so capable so many years ago - must be close on 30 years back - then with modern digital techniques it must be possible to do better than simple acceptance of a limitation that kills people!

I accept what you say about military radars and the problems with maintenance and operator traing. However I would suggest that military usage puts demands on both the equipment and the operator that are very different to the bridge of a ferry. Perhaps looking at other related disciplines may help, for example looking at radio astronomy will show a number of techniques for extracting useful signals from a high noise background. There are doubtless other, better examples.

In the end the issue comes down to signal processing and with modern digital techniques it must be possible to significantly improve on the performance that was apparent on PoB.

 

[achwilan]

I agree with you. One obvious outcome of many years of technical progress in detection area is that current operators are inclined to relie a bit too much on their hardware capabilities (anti-clutter is an example). 30 years ago, operators had to "read" their radar picture , and were trained for that; that's a declining art as we can see here; so human factor is 80% as usual... (suggested in MAIB rpt : disconnect anti-clutter...).

 

[peterb]

We had an interesting time last year trying to find Pye End Buoy (off Harwich) with a small boat radar in a force 5. Found that if you watched very carefully one bit of clutter kept on coming up in the same place. But you had to watch <u>very</u> carefully, and we knew roughly where it was. Pye End By has a small reflector, but adjusting the anti-clutter level didn't seem to make any difference to the contrast between the buoy and the surrounding waves.

 

[bilbobaggins]

[ QUOTE ]
In the end the issue comes down to signal processing and with modern digital techniques it must be possible to significantly improve on the performance....

[/ QUOTE ]

I would agree in large measure with much of your comment. There are many more considerations, of which a few....

Maritime radars perform to internationally-agreed IMO standards, for essentially merchant marine purposes. There certainly is kit available that will 'count the rivets on the hull', but I'm of the opinion that such would still be prohibitively expensive for any suggestion of retrofit on merchant vessels.

....And the 'target' must *still* provide a sufficient Radar Equivalent Echoing Area to bounce back enough rf energy, so that the 21st century MilSpec anti-submarine warfare stuff fitted to a cross-channel ferry will have a signal strong enough, and persistent enough, to be processed. A steel-hulled 30' fishing boat from Weymouth - in a lumpy sea - might well reflect a sufficient signal for a good rad operator to pick it up with careful use of the manual controls, but a 25' GRP sailboat may well not ever provide enough signal to be processed.

I'm afraid that the short-term answer for us is to make our wee boats considerably less 'stealthy'. That's very much in our interests. So also is an attitude of zero complacency by all of us. The ball is, for now, firmly in OUR court.....


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