Attaching Radar Reflector

[dlochner]

Very interesting position taken by US Sailing on being "lulled into a false sense of security". I work with data for a living, so I'm usually pretty skeptical until I see what the data says. I own a Davis reflector, and I'm hoping to get a friend to turn on his radar for me and see what I look like with the reflector hoisted in various positions, from various bearings and ranges. I have modest expectations, but hope to get some repeatable results which will work for my boat. Like everyone else who owns a radar reflector, our hope is that it provides some greater level of reflectivity. I just want to KNOW what I'm getting, rather than hoping.

If you read the full report there is a considerable amount of data. The tests were done in a controlled condition on land, so reflectivity could be accurately measured. In the other article, from Yachting Monthly, they compared on the water tests with the controlled condition tests. For most of the reflectors images from the radar screen are shown. All in all, the data is pretty compelling.

As a side note, the report was on the US Sailing website, I am not at all certain US Sailing has an official position on reflectors. CEC, ORC, and the USCG have standards which some reflectors meet.

 

[jssailem]

it was odd how many aluminum fishing boats would appear out of the fog, visually, that were not on screen (or were so intermittent that it was hard to ID them as a firm target.

I know that experience. This one came out of the fog speeding to the fishing ground doing 30 something. Visibility was about 50-70 yards.

That is @LeslieTroyer in Mahalo guiding the fisherman back to my boat. I was dead in the water after getting hit.

I think the angles when he was bow on served to minimize his radar reflection. He was not seen on our combined radars. Only visual observation helped to mitigate a catastrophic collision.

 

[tfox2069]

If you read the full report there is a considerable amount of data. The tests were done in a controlled condition on land, so reflectivity could be accurately measured. In the other article, from Yachting Monthly, they compared on the water tests with the controlled condition tests. For most of the reflectors images from the radar screen are shown. All in all, the data is pretty compelling.

As a side note, the report was on the US Sailing website, I am not at all certain US Sailing has an official position on reflectors. CEC, ORC, and the USCG have standards which some reflectors meet.

Agree - reading the report now. Its here:

https://www.ussailing.org/wp-content/uploads/2018/03/2007-Radar-Reflector-Test.pdf

 

[jssailem]

Reading through this report, the Davis appears to be average in performance. A bit better when healing. Much better than the Plastimo Tube in the tests. It is better to be placed high than on the deck.

Nothing appears to be "perfect". We are back to the concept of compromise that so often is a part of our boating lives.

Stay alert. Of note the test was looking for 5 hits out of 10 by a trained radar observer. Makes you wonder what it is like for novice boat owner.

 

[JohnShannon]

The one that is really cool is the Sea-me active reflector, this has a huge cross section but probably illegal in the USA. Also only works in one of the two radar bands. This investigation was the result of the sinking by a ferry of a small sailboat.

 

[Bob S]

Working on the boat today I found this unassembled in the port lazerette.

I was curious about mounting and found this post. These things have sharp edges. The backstay will keep it away from the sails but I don't know about you but my topping lift sometimes wraps around my backstay. My mast is on saw horses so mounting it should be easy. Might as well use it.

 

[jssailem]

Bob, that one is not intended for the back stay.
The backstay on has a cut in it so that it attaches flat against the stay.

see the hole in the center.
I have attached the instructions manual for your review.

 

[dlochner]

The usual place for a radar reflector is suspended from the port spreader. It will take 2 blocks on the spreader to get the halyard away from the sharp edges of the reflector.

 

[Ken Cross]

So I've had my H36 for a year now, and have been learning the radar lately. Given this thread, I thought you might find a recent experience interesting. I've been running my Garmin GMR 18 HD radar during the daylight to both learn its functions, and to see what things look like on radar when I can actually see them during the day (so I can understand what I'm looking at on the radar in periods of reduced visibility).

Two weeks ago, in broad daylight, I had a Catalina 38 motor past me with its Davis radar reflector up above its spreaders, in plain unobstructed view of my radar. You can see the boat, less than 1/4 mile away, on my port bow as the yellow blob. By contrast, you can see a buoy with its own reflectors (admittedly more than the Davis) in the upper left of the photo. When I zoomed out I was surprised to find that other boats painted a very similar profile to the Catalina with the Davis reflector, essentially indicating no significant difference with or without the reflector.

Not scientific, just an anecdote at this point, but I'll continue to watch with interest.

/QUOTE]
Someone (Practical Sailor I think) did some testing a few years ago and found many radar reflectors were really poor performers.
the ones they liked were the ones that are made from flat aluminum pieces forming a ball. These are the type you see all the time. (Like the one shown by Jsaalem above).
The smaller profile ones were said to be nearly useless.

Ken

 

[FastOlson]

I also recall reading the PS evaluation article. One takeaway was that having a reflector of any kind was always better than not having one. We have used the round shape in reply 27 for a decade in a prior boat, on its backstay.
Current boat has a tubular one on a shroud, above the first spreader.

Anecdotal evidence: back when bought this boat in the mid 90's it came with an early Apelco LCD radar, and it worked well. A memorable test was when motoring along about a half mile away from a buddy in a similar size sailboat and finding that I could not get his boat to solidly display on our screen -- so I called him on the VHF and asked him to bring up his uninstalled reflector from below decks. As soon as he brought it into the cockpit and fitted it together, his boat showed a strong return on our screen.
We were both convinced.

Like a lot of things in life, "perfection is the enemy of the good".... so do your due diligence, and go ahead and put up a reflector so your boat has a better chance of showing up.

 

[dlochner]

I also recall reading the PS evaluation article. One takeaway was that having a reflector of any kind was always better than not having one. We have used the round shape in reply 27 for a decade in a prior boat, on its backstay.
Current boat has a tubular one on a shroud, above the first spreader.

Anecdotal evidence: back when bought this boat in the mid 90's it came with an early Apelco LCD radar, and it worked well. A memorable test was when motoring along about a half mile away from a buddy in a similar size sailboat and finding that I could not get his boat to solidly display on our screen -- so I called him on the VHF and asked him to bring up his uninstalled reflector from below decks. As soon as he brought it into the cockpit and fitted it together, his boat showed a strong return on our screen.
We were both convinced.

Like a lot of things in life, "perfection is the enemy of the good".... so do your due diligence, and go ahead and put up a reflector so your boat has a better chance of showing up.

A radar reflector won't make your boat invisible on radar, it just might not make your boat as visible as you think. Some are better than others and all have their weak points.

There have been a couple of good evaluations of radar reflectors by Practical Sailor and others. A internet search will yield them. There was one highly rated reflected that is no longer made. I forget the brand.

 

[dLj]

In some earlier thread on radar reflectors, and after I read the PS article, I posted a question that was never answered. No big deal, I'm just posting it here again in case someone would like to check it out and tell me if indeed it's true.

Many years ago sailing with a good friend of mine, the question came up about radar reflectors. I asked him about the commercially available reflectors and he told me basically the same that the PS article said when written years later. Some are ok, some don't do much. But he went on to say if you really want a good radar reflector, take a gallon jug filled with water and hoist it up as you would a commercial reflector. That would give you an excellent radar reflector.

I've always wanted to check that statement out. Because it's sure a lot cheaper to take a plastic gallon jug left over and fill it with water and hoist it up. Darned easy to replace also if anything happened to it.

Anyway, as I don't have radar, I have no way to check this, but if anyone out there that does and wishes to give it a try, I'd love to find out.

dj

p.s. I just read this thread from the beginning and observe this is the "earlier thread" I allude to in my first sentence.

 

[Bob S]

Whether it work or not I don’t think you would want that much weight up high.

 

[dLj]

Whether it work or not I don’t think you would want that much weight up high.

I'd think if you have a set-up where you can run it up with a pulley system on your spreaders, you could hoist it when you are nearing higher traffic areas, or running in fog and give yourself a great light-up for other boats radar - if indeed it works. I mean really, a plastic gallon of sea water only weighs about 9 pounds (approximately, including the container and rope and fasteners). I don't see how that's going to do much, especially if you are only using it when you feel its needed.

I know for me, if I actually knew the answer and indeed it gives great visibility to radar to my boat for others, I'd go through the exercise of putting it up and down when going into or out of shipping lanes, or running in fog, that sort of thing.

dj

 

[JamesG161]

My radar by Raymarine® tells me if they see me.

I have confirmed this up to 5 nm from IC tug boats.

Newest models include AIS too.

Todays radars on larger vessels are very sophisticated.
Jim...

 

[Terry Cox]

Used to mount ours on the back stay, but wind would cause it to oscillate making noise while trying to sleep in the aft cabin. Moved it to the port side spreader flag lanyard that raises it to the first spreader.