Do I need a radar reflector?

[Adelie]

For passive reflectors Large Viking Tri Lens is the best on the market, 16” octahedral in catch rain position is 2nd best, as large as you can fit.

This is assuming you are on a sailboat that is heeled. On a multihull or power boat that doesn’t heel then others become more viable.

https://www.ussailing.org/wp-content...ector-Test.pdf

[dougweibel]

I would certainly agree that an active system will be seen far more often than a passive reflector. However, I would not recommend an active reflector to the OP without knowing his sailing plans. Every boat does not need the best equipment in every category. I certainly wouldn't recommend someone spend the money for an active reflector if they only rarely expect to sail in poor visibility. I would in that case still recommend having a passive reflector, at least stored in the lazarette or wherever. The three-plate spherical reflectors take up hardly any room when collapsed and if you suddenly find yourself in poor visibility only take a couple minutes to rig and run up a flag halyard.

OTOH if my home cruising ground were Maine I'd want radar, an active reflector, an AIS transceiver and a fog horn built into my loud hailer.

[RaymondR]

Interesting thread.

The three targets on the aft quarters in the image below between the 1/2 nm and 1 nm range rings are nav markers on posts. They are about 2 1/2' high and 2' wide and made from flat plates in a X form.

The target directly astern just beyond the 1 nm range ring is a car carrying ferry and more than 100' long.

Probably as good a demonstration of the effectiveness of decently sized reflectors but how would you install something like these on a sail boat?

[StuM]

Originally Posted by freshalaska

Fog horns help if heard or you can call out a pan pan with you position and heading.

Please learn the purpose of a pan pan call and when it should be used.

[Tenedos]

My view on this has drastically changed after we did a coastal sail along the California coast last year from San Francisco down to Mexico and back.

My view prior to the trip: Radar reflectors don't matter that much.

My view now/after the trip: DO GET a reflector, ignore all the chatter around whether they are effective or not.

For reference, I do have an AIS transceiver, a radar that I installed for this trip and a chart plotter at the helm that overlays radar and AIS.

Here are the things I observed during our trip:

First of all, not everyone has an AIS transponder, in fact for pleasure boats and many fishing boats we came across, we found that to be quite rare.

In poor visibility and especially at night passages, we found the radar to be invaluable. There have been numerous instances at night where there was no visual contact, nor was there anything on AIS but the radar warned us about nearby vessels.

Now, why do I think radar reflectors matter? For the vessels that we could make visual contact after seeing them on radar, there was a very significant difference on their radar footprint. Tiny recreational fishing boats showed up large, large looking boats barely showed up etc. I don't know what reflectors they used (if any) but the radar footprint was clearly not correlated to the size of the boats.

I now do carry two cylindrical radar reflectors on two shrouds. Are they effective? I have no idea but if hell feels better.

[a64pilot]

Originally Posted by RaymondR

Interesting thread.

The three targets on the aft quarters in the image below between the 1/2 nm and 1 nm range rings are nav markers on posts. They are about 2 1/2' high and 2' wide and made from flat plates in a X form.

The target directly astern just beyond the 1 nm range ring is a car carrying ferry and more than 100' long.

Probably as good a demonstration of the effectiveness of decently sized reflectors but how would you install something like these on a sail boat?

An issue with very effective reflectors is that they are very directional, the more effective they are, the more directional. It’s sort of like a spotlight, very bright if it’s on target, but not at all if it’s not.
How this relates to boats is as we roll around our target will appear and disappear, looking more like normal wave echos etc than an actual target. Then when we heel, it’s very likely that unless the reflector is gimbal mounted to stay level that it won’t reflect at all, or actually it does reflect, but up into the sky or into the water.

So with any passive reflector you have to choose between a reflector that will give a good strong return, but only in a very narrow cone vs one that will return over a broad range but do so very weakly.

It’s Physics your up against and it takes in my opinion a reflector about 2’ on a side to give good / great performance, and that’s too big for most boats. Of course even bigger is better, but it’s also important to note that a reflector that is twice as big doesn’t have twice the reflection, it’s many times more than twice. I suck at math, but trust me a 2’ reflector will reflect many, many times as much energy as a 1’ reflector.
So I run my Radar, and I have a good AIS and antenna, with no blind spots.
A friend has a Ketch. Separate AIS antenna mounted on the Mizzen, he can’t transmit or receive AIS directly ahead. We found that out buddy boating back from the Bahama’s, we couldn’t see each other when he was only a mile or so behind me. If he turned 20 degrees or so we would both pop up on each other’s screens.
I believe that most things that I worry about running me down will both show up on my Radar and they have AIS, meaning ships.
However really foggy days where I cruise are about as rare as total eclipses too, so that’s another reason, if I sailed where there was frequently fog and ships, I’d have a dual band active reflector, both X and S band.

[Lodesman]

Originally Posted by Breaking Waves

You have chopped off a pretty important part of the Canadian law . . . the whole 'unless' section . . .

I challenge your characterization of that part of the rule as "pretty important" - it's called Cruisersforum, not Kayakersforum or Inlandlakesforum.

[freshalaska]

Yes stewM I do know the difference and did correct my own mistake. I do not make a pan pan call when calling my position in the fog.

[Breaking Waves]

Originally Posted by Tenedos

t
I now do carry two cylindrical radar reflectors on two shrouds. Are they effective? I have no idea but if hell feels better.

Please, please read the test reports. I posted links earlier. You will learn a lot. And one thing you will learn is those shroud tube reflectors are the worst possible.

ofc if they simply 'make you feel better' it's all good

Originally Posted by Lodesman

I challenge your characterization of that part of the rule as "pretty important" - it's called Cruisersforum, not Kayakersforum or Inlandlakesforum.

Quite a number of local coastal 'cruisers' could/would fall into those exceptions. And you are being disingenuous when you quote a law, but only include the part that suits you and don't mention you are leaving out the part that does not suit your story.

Reading further in the Canadian bulletin its pretty obvious they want boaters to read the reports and realize that the basic facts that yachting size passive reflectors don't meet the simple iso requirements for rcs and only perform at that 'lower than iso standard' with excellent placement/position . . . . and that if you really want a significant increase in radar visibility only an active unit will do it.

A64 is again correct . . . if you could mount a 2 1/2' trihedral reflector in the optimum position you would have something . . . . but yea that's not going to happen on most of our boats. Note: the rcs goes up with the 4th power of the side length of a trihedral.

[Tenedos]

Originally Posted by Breaking Waves

Please, please read the test reports. I posted links earlier. You will learn a lot. And one thing you will learn is those shroud tube reflectors are the worst possible.

I had read them before buying, and I decided to buy them ;-)

To be clear, I get the tube types are the "worst" among the options but I cannot see how they would harm. From what I understand, they are most susceptible to angles they have, hence I put two on two shrouds at different angles, so they can cover a broader range of heeling angles.

[landlockedgm]

Turn your radar on during the day and watch, even yours will show any boat. Any radar on a big boat will see you if they are looking. My Garmin always shows any kind of boat with good range.

[Breaking Waves]

You really read this and still bought it? Well, ok, then at least you knew what you were getting.

"The two Mobri tube reflectors performed as might be expected, and were essentially invisible. Only the larger 4" diameter (2" radius) device came anywhere near detectability, with an average return at a 0° angle of heel of just over 1 m 2 , with no deep nulls. On S-band, the average return was almost 0.5 m 2 , not enough to be detected, but better than most. When heeled, however, things fall apart and the return drops to a few duck units (see fig. 8). The smaller Mobri is invisible under all conditions, and, with its minimal windage, might make a nice addition for the Stealth Bomber."

That is Stan Honey's writing, who knows his stuff in this area as well as anyone in the world, has no axes to grind and does not pull his punches.

[Calif.Ted]

Don't know if it was the reflector or not but I once hit a fog bank under sail with a large whale watching vessel behind me, after a while couldn't tell if he was closing on me so I radioed. He said not to worry I was making a nice bright target and to call back if I ran into the whales.

[CaptTom]

The experts all say the tube models don't work. The fishermen use the "high flyer" reflectors on their gear shown in one of the earlier posts. Their livelihood depends on them finding their gear.

On my last boat, I had a large (maybe 10"-12" across") aluminum reflector mounted in the "catch rain" position tucked in a stowage area behind a layer of fiberglass (the outer hull.) Everyone said it showed up like as a very strong target on radar. I'm pretty much sold on the cheap commercial grade relectors.

[landlockedgm]

Stop wasting money and buy something you really need.