Do I need a radar reflector?

[a64pilot]

You have actually an excellent point and that is if a Radar can’t see your mast, rigging etc. that it’s also very likely to not see a consumer Radar reflector, cause the RCS of a mast and rigging isn’t small, and being roundish is actually sort of an advantage, the perfect reflector that will always reflect at any angle is a ball, but the reflection is weak, corner reflectors work by focusing the signal and returning it, exactly like a flashlight reflector, but they are very directional, they have to be angled just right and heeling or rolling will most likely take it out of the correct position often.
Most Radar reflectors are sold not based on actual performance, but what the consumer wants, and they don’t want a big corner reflector that would work cause it’s too much windage, will get caught in stuff, as well it’s just plan ole ugly.
What I would like or have is about a 2’ corner reflector that would fold flat and be stored and that I could bring out when it’s needed. I contemplated having a few court out at the laser where I used to work, but never found the pattern.
But between my Radar and AIS, I have never been surprised by another vessel.
I’ve almost been run down by a Commercial fishing boat that as it went by you could see there was no one in the wheel house, but I saw it coming, and a Radar reflector would not help if no one is looking.

However none of them cause any harm, just most don't actually increase your boats RCS by much, often not enough to matter.

For a ships ARPA to work it needs a strong and constant return, returns that come and go which most directional reflectors will are often discounted as wave returns.

I think the active dual band reflector is about $1,000, odd that as far as I know there is only one brand? I guess being seen isn’t all that high a priority? However I’m constantly astonished at how many million dollar yachts do not transmit AIS.

[markpierce]

If you had a metal boat, a radar reflector would be unecessary.

[markpierce]

Originally Posted by roland stockham

Only real way to know is to go on another boat with radar and see what your boat looks like at close range and about 3 miles. If you cant see it then you are radar invisible. If possible check it in fog or light rain as well.

[a64pilot]

Military Radar isn’t at all any comparison. The Longbow Radar that I was most familiar with, if I flipped the “zeroize” switch, it would do over a Million dollars worth of damage by burning circuit cards in the Radar Processor box, so how much did the Radar cost? Who knows, but it is a phenomenally good Radar, to begin with it’s pretty big, and a big antenna with Radar really, really helps.
Aircraft Radar isn’t any real comparison either, because there is no ground clutter with aircraft, their background is just space, so no returns at all, except the aircraft, and ground clutter or sea state is extremely difficult to pick out a target on the ground or on the ocean.
With aircraft look down Radar one way was with a Doppler notch, meaning anything moving less than a set speed would be ignored, but a sailboat on the ocean, that won’t work.

Picking us out of the Ocean with the waves around us etc, is actually a very difficult thing for Radar to do, it’s sort of like finding Waldo. In any real sea state I don’t think a ship Radar is likely to see us without an active reflector, even if we had a steel hull, we are tiny compared to a ship and his Radar has a look down angle that makes it even tougher, easier for us to be hidden in the sea state.

[contrail]

FWIW, I used to be a strong radar reflector proponent. Then, one day in my current boat, a 45 foot cat, I was sailing along with no reflector and a cruise ship went by. I asked if he could see me on radar (because I had no reflector up), and he laughed and said they had been watching me from as far as 16 miles away. That made me wonder about the mast (71 feet) and all the other metal. I eventually theorized that perhaps the outboard (which rides on the dinghy in high davits - it's about nine feet above sea level) was the reflector. That dinghy was a fiberglass RIB. Now it's an aluminum RIB, which should add to the reflecting surfaces. Anyway, after that encounter, I didn't worry so much about the reflector. It's pretty well buried in a locker. It is also possible that since my boat is a cat, which doesn't heel much, some of the normal assumptions are incorrect.



On the other hand, I have a B&G Broadband 4G radar, and if I manually tune it, I can pick up mooring buoys (plastic), and their dinghies. And, on my old JRC radar, I could pick up the outboard on an inflatable at one mile. So I am with those who think there may be more reflective surfaces than we think.

[AndyEss]

This is a really interesting and pertinent discussion. Thanks A64Pilot for sharing your thoughts and experiences. I did a lot of contracting work at US Air Force Bases and once had my mobile engineering test laboratory working directly in line with an Army flat panel (.phased array) weapons targeting mobile radar set looking at the air force dropping ordnance at a weapons range 70 miles away.
We were blasted with so much energy my computer keyboard typed gibberish by itself and occasionally the electric solenoid controlled hydraulic system would randomly activate a circuit - muy peligroso.
We finally pulled down the mostly wooden overhead back door of our laboratory, lined it with aluminum foil, and wrapped the PC keyboard in aluminum foil so we could get our engineering work done.

So far, what I have concluded from your, Mr, Hawley’s and others input, is those cute, inobtrusive tube reflectors are far less than useless as they apparently provide a really excellent level of false security.

[capt jolly]

In my fishing years b4 satnav/gps etc etc we perfected the art of making small dan bouys with only 1 or 2 miles effectiveness so the competition couldnt see our secret spots.
We had all sorts of tricks but by far the cheapest and easiest we found was simple ali cans, 2 or 3 crumpled and rammed down the pole was enough to pick out on low range. If you wanted really good ones for say 10 miles we used onion bags or similar with 10 or so and put out a signal like a ship!! A bag of old cans up your rig for a quick fix will not be outdone by expensive stuff. it all comes down to the kinks and angles that pick up the signal and throw it back out.

[GeneM]

When I worked on ships, I found that Radar reflectors worked well. I could tell when a sailboat had a strong radar blip.

It's only needed at night or in fog, because the boat is visible during the day. It's a good idea to also show a strong light to an approaching ship to be sure.

[HankOnthewater]

Post #8 and #16 showed the same document, although from different links/sources.
Here is another PDF file, as attached, although a bit older (from 1995), but it still makes valid points.

My opinion: to me it would not be high priority, particularly where/how I sail.
Disclaimer: I have one half way up the mast. Others tell I am visible on their radar.

[Lodesman]

Originally Posted by AndyEss

. My question is whether this RCS is actually greater than the reflective surface of a mast 60 ft long and 12 inches wide. Most masts are also elliptical rather than round, so they should reflect better on their major axis. Sail track, fittings, blocks, sail headboards, masthead lights, all should add to the rigging RCS, especially for the shorter wavelength X-band.

The problem with a mast is it has to be perpendicular to the line of sight to the radar antenna, for it to reflect back to that antenna. This means practically, that return is strongest at a very particular angle of heel, from the beam and falls off exponentially at any other angle of heel. The odds improve if they are looking at you bow or stern-on; and as previously mentioned a catamaran has an advantage.

[Lodesman]

Originally Posted by AndyEss

those cute, inobtrusive tube reflectors are far less than useless as they apparently provide a really excellent level of false security.

All equipment has limitations - and those tubes are exceptionally limited. But they do serve a purpose - they may satisfy a legal requirement if nothing else. One of these things came with my boat. I bought a large octahedral and mounted it in the approved "catch rain" orientation, so the cylindrical reflector is entirely supplementary. I mounted it to my MOB pole, which itself is attached by QR to a mizzen shroud. It is visible by my radar out to a couple miles, but it does help that I have an idea of where I'm looking and tune the radar to best effect - as I would if we had a MOB.

[boatpoker]

"Do I need a radar reflector" ...... Yes I do.

Certified RADAR/ARPA/MARPA operator.

[Breaking Waves]

Originally Posted by Lodesman

those tubes are exceptionally limited. But they do serve a purpose - they may satisfy a legal requirement if nothing else.

Well, looking at the UK requirement . . . probably not in most cases.

items 4 & 5 are relevant

"4.) Regulation 19 takes account of the fact that reflectors built to the above standards may not be practical for fitting to very small vessels. However whenever physically possible reflectors should meet the IMO standards."

If you really wanted to meet this regulation, and you have 12vt available, you could with an active unit. They are not hard to mount and are less intrusive that the big passive units. Clearly the Tubes come no-where close to the iso requirement

5.) Owners and operators of very small craft where fitting reflectors meeting IMO standards is deemed impracticable should fit reflectors with the greatest echoing area possible. In all cases the reflector should be fitted as high as possible for maximum detection range, following the manufacturer's instructions.

So if you 'can't' fit an active unit, then you are required to fit the unit with the greatest possible echoing area, and most clearly that is not a tube unit. Only if there is absolutely no possible way to fit one of the other units does the tube meet this.

The tubes also don't pass the current OSR standard, which enforcement officials often look to in order to judge what is practical for yachts.

So bottom line I don't think a tube actually passes the UK requirements for most of us.

The tubes may pass some law somewhere, but that would seem to be a poor reason to be using the worst possible choice.

[Lodesman]

Originally Posted by Breaking Waves

The tubes also don't pass the current OSR standard, which enforcement officials often look to in order to judge what is practical for yachts.

So bottom line I don't think a tube actually passes the UK requirements for most of us.

The tubes may pass some law somewhere, but that would seem to be a poor reason to be using the worst possible choice.

Do you understand the difference between "should" and "shall"?
I'm curious where you do your boating, and why you feel confident opining on what passes legal muster in various jurisdictions?

The tubes do function, but are limited in the practical sense to short ranges. For some smaller vessels and other uses they might be more practical than better larger devices. There are obviously much better options for larger vessels.

[Breaking Waves]

If you go down that "should" path, then this regulation is entirely toothless. Anything at all will qualify as a radar reflector - including your mast or a paper napkin.

That is clearly not the intent.

A more sensible interpretation would be to suggest that items which yachting itself, thru the OSR's, judge to be acceptable reflectors meet the rule and are in fact radar reflectors, and items which do not meet the OSR definition of an acceptable reflector are not.

But as always it is possible to dance upside down on the head of a pin with such legal questions.

I am puzzled by your defense of the tubes - they are very very clearly the worst possible choice in most cases. The 2" tubes essentially don't work at all and the 4" tubes work only thru a very very narrow angle range. The racing community looked at them and eliminated them as a choice. You are normally a seamanship and best practices sort of guy. Your stance here is odd in that context.