Radar Reflector

[Fr J Hackett]

I fitted a Echomax 230 BR in place of a Firdell Blipper 4 years ago because it was the only passive reflector that could satisfy the RORC regs at that time (despite numerous boats passing scrutiny with a Blipper which did not!) As to it's effectiveness all I can say is that I was picked up at 12 miles (visability less than 2) by a customs cutter in open water some 50 miles South of the Lizard. Out of curiosity I asked at what distance they had picked me up after we had got the formalities of identification over with. Whether it was down to the natural radar signature of the boat or the Echo max I don't know. I was also picked up at about 3 miles in thick fog in the Ushant TSS when I was in the middle of several vessels running AIS and radar and called a potential close encounter up on VHF ( thanks AIS ) the only time I have ever had to do it, he told me that I was clearly visable on radar and he had been tracking me for 10 minutes and would make the nessessary course adjustment.

 

[RUSSH]

There is no requirement to carry a radar reflector. The recommendation is included in the MCA's MGN 349 (M+F)

SOLAS says "shall", but SOLAS is not law. The MCA publication is a recommendation and says "should"

I'm no expert. That much I know for sure. But below is from SOLAS alluded to in the above MGN.


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 and supersede Merchant Shipping Notice M.1638.

1.) Reflectors meeting the standards laid down in British Standard BS 7380:1990 (ISO standard 8729: 1987) meet IMO performance standards*. Radar reflectors which were type tested and approved to the earlier DOT Marine Radar Reflector Specification, published in 1977, also comply with the IMO standards.

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.

3.) Regulation 19 takes account of the fact that reflectors built to the above standards are relatively large and may not be practical for fitting to smaller vessels. The Agency considers that fitting reflectors meeting IMO standards to vessels of 15m and above length should be practicable.

4.) Owners and operators of craft vessels of less than 15m in length should fit reflectors with the greatest echoing area practical. In all cases, the reflector should be mounted as high as possible for maximum detection range, following the manufacturer's instructions.

5.) It should be noted by Master and Operators of all vessels that even the 10 m_ reflectors referred to above will be difficult to detect in sea clutter on radar displays. Masters of all vessels are reminded that this should be taken in to account when setting lookouts and determining safe speed as required by Rules 5 and 6 of the International Regulations for the Prevention of Collisions at Sea.

6.) Electronic radar target enhancers are now marketed by some manufacturers. Radar enhancers can be considered as “other means” in the Regulation. These have a larger equivalent radar cross-section for a physically smaller size than radar reflectors and produce a response on a radar display, which is stronger and more consistent, but does not increase the apparent size of the target. Some navigation buoys are being fitted with electronic radar enhancers and seafarers should be aware this improves their detection range. Mariners should note that radar enhancers currently available do not operate in the radar “S” band.

7.) Owners and operators should note that under Regulation 18 equipment meeting the requirements of Regulation 19 must be type approved. However by virtue of Regulation 1.4, the Agency allows United Kingdom vessels which are too small to fit reflectors meeting the IMO standards to fit equipment suitable for the type and size of vessel.

I think the key word is practical and I guess none of it matters until the inquiry or coroners court!

 

[Ubergeekian]

Anything is better than nothing, but judging by the post-Ouzo investigations into passive reflectors, they're only just better than nothing.

You can download the report here

Is there any experimental evidence to back up their prediction that no reflector of any sort can be seen at 4nm range, but that almost any size of reflector is clearly visible at 6nm?

 

[Ubergeekian]

I have read the QinetiQ report - when it first came out - and it convinced me of what I said in my first post: passive reflectors are next to useless.

Most of the passive reflectors they tested gave a solid 2m^2, which was, according to their predictions, quite enough to be seen. Certainly not as good as an active system, but a hell of a lot better than a bare hull and mast. They only deprecated two reflectors: the 4" and 2" tube ones.

 

[boatmike]

There is no requirement to carry a radar reflector. The recommendation is included in the MCA's MGN 349 (M+F)

SOLAS says "shall", but SOLAS is not law. The MCA publication is a recommendation and says "should"

Well maybe that's true. I was under the impression it was in fact a legal requirement. But if you were in a collision in fog and NOT complying with SOLAS or MCA you would be on a very sticky wicket and I don't fancy answering an enquiry by saying "It's not a legal requirement" so the point is rather irrelevant I would have thought.

 

[boatmike]

Most of the passive reflectors they tested gave a solid 2m^2, which was, according to their predictions, quite enough to be seen. Certainly not as good as an active system, but a hell of a lot better than a bare hull and mast. They only deprecated two reflectors: the 4" and 2" tube ones.

I think that bears out my own experience too Uber. One fortunate thing about cats is they don't sail at a high angle of lean and actually make rather good radar platforms. Usually I see most other yachts on radar at about 2 miles in practice. Occasionally less, but seldom more than 4. Sometimes I don't see other small craft at all on radar until very close and Mk 1 eyeball usually then registers the absence of any reflector at all. Perhaps this range is very small when a tanker is on a collision course but it's better than now't. I therefore have a permanently mounted Ferdell Blipper and when in traffic or fog use the SeaMe. I could I suppose chuck the blipper now I have the SeaMe but anything that relies on electricery can go tits up when you need it most so I leave it there.... As you say, better than bare hull and mast.

 

[idpnd]

There seems to ba a lot more science in the Luneberg lens type of reflector than in any other passive type.

I understood the aforementioned report favoured the trilens. I find the active reflectors to be too expensive and opted for an ais transmitter (pretty much same price as an active reflector) and a medium sized trilens.

 

[Madhatter]

"ang "on a minute, most of the kit you are all talking about cost more than my wee little boat !!

Pardon my ignorance but do aluminium mast reflect radar signals ?

 

[RUSSH]

Well maybe that's true. I was under the impression it was in fact a legal requirement. But if you were in a collision in fog and NOT complying with SOLAS or MCA you would be on a very sticky wicket and I don't fancy answering an enquiry by saying "It's not a legal requirement" so the point is rather irrelevant I would have thought.

I'm with boatmike. I too believe it is a legal requirement. The relevant Regulation in SOLAS uses the word "requires"

"Regulation 19 para.2.1.7 requires radar reflectors to be carried, where practicable....."

but then gives the sort of opt out "where practicable". Given that I easily managed to fit a radar reflector, (echomax same as on RNLI Atlantic RIBS), to a 5.4M RIB in order to get it coded. You would probably struggle to suggest it's not practicable to fit one to anything larger.

But as I pointed out I'm no expert. Perhaps someone else can give a definitive view on whether it is a legal requirement or perhaps it's one of they wishy washy grey areas? I've gone for better safe than sorry.

As an aside I think there are 2 other legal requirements arising out of SOLAS V that apply to pleasure craft. One is to have a passage plan for each voyage the other is a copy of the distress signals.

 

[VicS]

My understanding is also that it is a legal requirement to carry a radar reflector and also the distress signals and to prepare passage plans where applicable.

 

[PerformanceSailor]

Reflections....

"ang "on a minute, most of the kit you are all talking about cost more than my wee little boat !!
Pardon my ignorance but do aluminium mast reflect radar signals ?

Actually, you ask a good question... turns out that the round shape of a typical sailboat mast has a very low echo potential. This is a case where our natural intuition can misinform us....

I recall being surprised that when I and my friend were talking on the radio and I could visually see him about a half mile away, the radar return was very poor. Wow, though, when he pulled out his old aluminum Davis reflector from inside and placed it inside the combing on a seat - Big Dot on the screen! His boat is a 33 foot racer/cruiser with a tall rig, too.

LB

 

[Madhatter]

Actually, you ask a good question... turns out that the round shape of a typical sailboat mast has a very low echo potential. This is a case where our natural intuition can misinform us....

I recall being surprised that when I and my friend were talking on the radio and I could visually see him about a half mile away, the radar return was very poor. Wow, though, when he pulled out his old aluminum Davis reflector from inside and placed it inside the combing on a seat - Big Dot on the screen! His boat is a 33 foot racer/cruiser with a tall rig, too.

LB

Could you put folded tinfoil inside the mast ??

 

[l'escargot]

Well maybe that's true. I was under the impression it was in fact a legal requirement. But if you were in a collision in fog and NOT complying with SOLAS or MCA you would be on a very sticky wicket and I don't fancy answering an enquiry by saying "It's not a legal requirement" so the point is rather irrelevant I would have thought.

From the MCA Site:

"SOLAS V For Pleasure Craft

On 1 July 2002, some new regulations came into force, which directly affect pleasure craft users. These regulations are part of Chapter V of the International Convention for the Safety of Life at Sea, otherwise known as SOLAS V. Most of the SOLAS convention only applies to large commercial ships, but parts of Chapter V apply to small, privately owned pleasure craft. The following requirements apply to all craft, irrespective of size. If you are involved in a boating accident and it is subsequently shown that you have not applied the basic principles outlined in this document, you could be prosecuted.

VOYAGE PLANNING
Regulation V/34 ‘Safe Navigation and avoidance of dangerous situations’, is a new regulation. It concerns prior-planning for your boating trip, more commonly known as voyage or passage planning. Voyage planning is basically common sense...

RADAR REFLECTORS
Many large ships rely on radar for navigation and for spotting other vessels... If your boat is less than 15m in length, you should fit the largest radar reflector you can. Whatever size your boat is, the radar reflector should be fitted according to the manufacturer’s instructions, and as high as possible to maximise its effectiveness.

LIFE SAVING SIGNALS
Regulation V/29 requires you to have access to an illustrated table of the recognised life saving signals...

ASSISTANCE TO OTHER CRAFT
Regulations V/31, V/32 and V/33 require you:

to let the Coastguard and any other vessels in the vicinity know if you encounter anything that could cause a serious hazard to navigation, if it has not already been reported. You can do this by calling the Coastguard on VHF, if you have it on board, or by telephoning them at the earliest opportunity. The Coastguard will then warn other vessels in the area.

to respond to any distress signal that you see or hear and help anyone or any boat in distress as best you can.

MISUSE OF DISTRESS SIGNALS
Regulation V/35 prohibits misuse of any distress signals. These are critical to safety at sea and by misusing them you could put your or someone else’s life at risk.

NAVIGATION
With respect to navigation and collision avoidance any vessel that proceeds to sea, irrespective of size, is required to comply with the Merchant Shipping (Distress Signals & Prevention of Collisions) Regulations 1996. It is of paramount importance that all vessels at sea comply with the International Regulations for the Prevention of Collisions at Sea. These are contained within the Merchant Shipping regulations that also set out the penalties for non-compliance, which could be a fine of up to £50,000 in serious cases...

MANNING
Provided it meets the following requirements a pleasure vessel which is less than 3000 GT has been exempted from the Merchant Shipping (Safe Manning, Hours of Work and Watchkeeping) Regulations 1997:..

CREW AGREEMENTS, HEALTH AND SAFETY AT WORK AND FIRST AID KIT REQUIREMENTS
Any pleasure yacht of any size and with 5 or more paid crew, undertaking non-coastal voyages will require crew agreements and crew lists...

POLLUTION
The requirements of the international pollution prevention regulations (MARPOL) apply to all vessels but for pleasure vessels no survey is required..."

Here:http://www.mcga.gov.uk/c4mca/mcga07...pleasurecraftandsmallships/pleasurevessel.htm

The fact that you could be prosecuted for non compliance would suggest that it is a legal requirement.

 

[Ubergeekian]

Pardon my ignorance but do aluminium mast reflect radar signals ?

Yes, but not in the right direction. Imagine lobbing ping pong balls at your mast. The very few that hit it straight in would bounce back at you, but almost all would hit a curvy side and get bounced off at an angle.

Now imagine lobbing the balls into the corner of a cube. Whichever side it hit first would reverse its motion in one direction, the next would reverse its motion in a second perpendicular direction and the third would whizz it back the way it came.

For "ping pong ball" now read "radar photon".

 

[Ubergeekian]

The fact that you could be prosecuted for non compliance would suggest that it is a legal requirement.

I wonder how small they would go. None of the Wayfarers at Kirkcudbright seem to have radar reflectors, and I'm not planning to put one on my Hunter 490 - which is 1" shorter than a Wayfarer.

 

[Coaster]

...The following requirements apply to all craft, irrespective of size.

...If your boat is less than 15m in length, you should fit the largest radar reflector you can. Whatever size your boat is, the radar reflector should be fitted according to the manufacturer’s instructions, and as high as possible to maximise its effectiveness.

Thank you for this information.

Perhaps the forum can advise me on the best radar reflector to fit to my youngest daughter's new kayak and which reflector is best for our inflatable dinghy?

 

[RUSSH]

Thank you for this information.

Perhaps the forum can advise me on the best radar reflector to fit to my youngest daughter's new kayak and which reflector is best for our inflatable dinghy?

I'm sure your query is tonge in cheek. But just in case. If it's not practicable to fit a reflector to a particular vessel under the specified length then you can't and you are not required to.

 

[bbg]

Most of the passive reflectors they tested gave a solid 2m^2, which was, according to their predictions, quite enough to be seen. Certainly not as good as an active system, but a hell of a lot better than a bare hull and mast. They only deprecated two reflectors: the 4" and 2" tube ones.

Selective interpretation. They said 2m^2 gave a significant chance of being seen "inside 2nm". That is closer than I would like as a first contact.
All passive reflectors had null or near-null returns at certain angles. That doesn't inspire confidence.

I think it is also important to recognise that the results on their own are somewhat meaningless. In order to make a fully informed decision, it would also be important to know that the radar return of the yacht is - but we don't have that data. What we do have is anecdotes of people saying "I brought this on deck and the radar signature improved". That is valuable information and suggests that even passive reflectors do work to a degree.

What I can take away from the report is that all of the passive reflectors gave RCS returns which are smaller than the physical size of my boat (and my boat ain't big). The SeaMe gave a return which was many times larger than the size of my boat.

One other advantage of an RTE is that I can mount it on the transom on a pivoting support. When I tack the boat I can tack the RTE, keeping it more nearly upright. I know that mounting it on the transom reduces the distance at which it can be "seen", but keeping it upright will make it more effective (and keep weight off the top of the mast).

I will continue to carry a cigar reflector (mounted under a spreader) and an octahedral in a flat pack - because my class rules require these. But the only thing I will rely on is the RTE.

 

[Robin]

I fitted a Echomax 230 BR in place of a Firdell Blipper 4 years ago because it was the only passive reflector that could satisfy the RORC regs at that time (despite numerous boats passing scrutiny with a Blipper which did not!) As to it's effectiveness all I can say is that I was picked up at 12 miles (visability less than 2) by a customs cutter in open water some 50 miles South of the Lizard. Out of curiosity I asked at what distance they had picked me up after we had got the formalities of identification over with. Whether it was down to the natural radar signature of the boat or the Echo max I don't know. I was also picked up at about 3 miles in thick fog in the Ushant TSS when I was in the middle of several vessels running AIS and radar and called a potential close encounter up on VHF ( thanks AIS ) the only time I have ever had to do it, he told me that I was clearly visable on radar and he had been tracking me for 10 minutes and would make the nessessary course adjustment.

We once called Ushant Traffic Control when approaching Chenal Du Four in thick fog to ask about visibility in the Four itself. They asked us for our position and then told us they had us on their radar at 15mls range, that was in a Westerly 33 foot ketch with a Firdell Blipper.

I have to say practical experience over many years of yacht radar use has me questioning the test results that say reflectors are not very good. I certainly agree about the Mobri tube ones, so often fitted horizontally even on French boats, but otherwise we have always found yachts with good reflectors properly mounted to show at around 4mls out, if the radar is properly tuned and set for the conditions and range in use and if it is monitored rather than just glanced at occasionally. Yachts without hoisted or fitted reflectors would show a very intermittent echo, easily missed without continuous monitoring unless the set had 'track' or 'trail' in use which retains a shadowy image on screen to show target movement. We once came across a wooden ketch with wooden masts in rough seas and fog that didn't show on radar, but passed visually by about 25yds away.. I would expect big ship radar to pick up yachts at better than we could on yottie sets, simply because they have a higher and more stable platform and much more powerful sets, but whether the return is good enough to register on their ARPA displays at the same range is debatable, and I guess continuous monitoring might be asking too much of some bridge crews when automatic electronic alarms are available from their ARPA?

 

[Ubergeekian]

Selective interpretation. They said 2m^2 gave a significant chance of being seen "inside 2nm". That is closer than I would like as a first contact.

First contact is different. If you look Figure 1 on page 7, you'll see that although they say you need 2m^2 to have a 50% chance of detection inside 2nm, radar cross section was thought much less critical at greater differences. At 3 miles, for example, they predicted 80% for 2m^2 and 95% for 10m^2. If first contact was at 6nm, a 2m^2 RCS reflector would give a 97% chance of detection and a 10m^2 one 100%.

However, there model also says that no reflector of any size could be seen at 4nm. I would be very interest to know if people who use radar have seen this effect.