Do I need a radar reflector?

[boatpoker]

Originally Posted by kelpline

If you have a friend whose boat has a radar, sail your boat about 2 miles away and ask the friend if your boat can be seen on their radar.

and have him sail in circles as the reflection will change dramatically with aspect.

[leon.opit]

IMHO having spent years cruising on yachts from 10m to 14m passive reflectors are next to useless. I habitually ask passing ships what my echo looks like, especially on night passages when I am getting a bit bored, becalmed etc. I have used big mast mounted reflectors, tube, stay mounted reflectors and no reflector. The responses from the ships would indicate that the relative angle of my hull to them is what really makes a difference. What really works is an 'active reflector' a small very low power piece of electronics that emits a radar signal when it detects that it has been 'illuminated' by another radar, known as 'transponding'. From responses I can say that these really work well(at least the good models) and seem to make us appear as quite a substantial vessel which is always agood thing! Of course they cost more but if you are regularly in traffic, especially at night, I would say they are a good investment. I have no commerical interest in these devices.

[Ken Pole]

FWIW, most military vessels understandably do not transmit AIS.

[a64pilot]

Originally Posted by Rorzech

WHY wouldn't a 4 X 8 foot piece of that reflective Mylar bubble wrap they use as radiant heat reflective insulation. just make a 4 foot diameter tube with it around your mast. When the fog lifts just roll it up and stow it. It should stand out on radar like a metal boat !

Although it’s silver in color, it’s actually plastic.

[a64pilot]

Originally Posted by Ken Pole

FWIW, most military vessels understandably do not transmit AIS.

As a Retired Military Officer, I don’t understand why, certainly in times of war or even “heightened tensions” or off the coast of Somalia if patrolling for pirates etc, but why do so in Civilian shipping lanes and waters? Do they run lights off at night too?

Them not running AIS in peacetime would be similar to me flying a Military Aircraft transponder off in my opinion. There is no training value in doing so, but there is certainly a safety concern.

[Kerryf]

I nearly got run over in the English channel by a container ship. Calm seas and thick fog. The boat was a 34 foot fiberglass Island Packet sailboat. I had just installed one of those tube radar reflectors. I raised the ship on VHF and asked if he could see us on radar. After a moment, while he tuned in his set, he reported that he could see us now. He passed less than 50 feet from us.

So often this is the case and it's happened to me on radar equipped ships I've driven, I see a small boat ahead that is not showing up on the radar. After disabling Autotune and micro adjusting the gain etc I can get it to show up.

I swore I would never go to sea as a passive observer again, relying on others to avoid me. At a minimum have an AIS transponder, it pings all modern radars and ECD's. Preferably in times of bad visibility: man the radar, make sure its tuned in correctly. Be active about your life preservation.

I saw a cruise ship pull into St Thomas USVI one morning back in the late 80's with a small yacht mast entangled in its anchor. The captain stated he had no idea.

[a64pilot]

Originally Posted by boatpoker

and have him sail in circles as the reflection will change dramatically with aspect.

Even then it only tells you what you look like to another small boat with that particular Radar, mounted as it is.
A Ship Radar is of course completely different, it’s much better, higher power and mounted up much higher, the higher mounting makes it harder to pick you out in any appreciable sea way as it’s looking down and you don’t break out vertically from the sea state.

We used to train against a Roland missile system unit in Germany, when they mounted their Radar on a hill top, they could see a long ways, and it was excellent for detecting airplanes, but helicopters can get in and amongst the trees and often they couldn’t see us and we could “get” them.

However if they put themselves down in a valley, they couldn’t see as far of course but they were nearly invulnerable, I had one “get” me when I was actually ground taxiing under a set of large power lines, as soon as my rotor system came in his line of sight, he had me.
The reason is ground clutter, when on a hill we could hide in the ground clutter, but him looking up we didn’t have any ground clutter.

Same with a ship, his Radar mounted up high like that he has a look down angle at us and we can easily “hide” in 5 or 6 ft or larger waves, maybe even smaller ones. Another ship of course cannot, and his Radar is I bet optimized and designed to see other ships, not so much little boats.

[369thegoose]

Originally Posted by Discovery 15797

You don't require one by USCG regulation, and no a radar tx/rc does not act as a reflector.

But I was specifically asked if I had one in my most recent survey...which would imply that insurance companies might require one if the surveyor notes that one is not onboard.

Slug and BreakingWaves are both correct. They work do some degree, but they generally do not paint a consistent target, so you must be vigilant. Active units are best. The EchoMax Active-XS reflector is about $1,000. Probably worth the expense if you are in an area with lots of fog and high vessel traffic.



Passive reflectors don't have to be especially large. A flat 3' square metal plate will return a radar cross section of about 10,000 square feet when viewed perpendicular to the surface. This is the key...the best return is when the target is perpedicular...which is why passive radar devices return intermittent targets...they are small and their small plate is not always perpendicular to the radar antenna.

Fog doen't affect the effectiveness of a passive radar reflector...it is a passive device. The strength of the radar rx/tx and the rx ability to minimize clutter and noise caused by atmospheric conditions like rain, sea state, etc. may affect the ability of your radar to discern the return from a passive reflector.

Also, you should not call pan pan when maneuvering in dense fog. Maybe "sécurité, but not "pan pan." But if you're in an area where you have occasional fog and don't have radar...you probably shouldn't be underway even if you have AIS, or you should be moving 'dead slow."

And blow the horn continually

[Aethelwulffe]

Those things in the image are only radar reflectors secondarily. Primarily, they are DAY SHAPES. They are actually very poor corner reflectors (radar reflectors) compared to the intentionally capsule shaped, non-dayshape multiplex corner reflectors that look kinda like a fender. Those, you send up the mast, and they really give a big blip. That dayshape you have means you are at anchor...don't put it up unless you are at anchor. If you are at anchor, don't stay that way unless you do put it up...and on a signal halyard off your spreader, not on the main or something.

1. A single ball day-shape indicates a vessel (or object that is not a buoy , daymarker or other navigational feature with its own shape indicator) that is at anchor.

2. The Cylinder you had actually means "vessel constrained by draft".


You can check the ColRegs https://www.navcen.uscg.gov/pdf/navRules/navrules.pdf for this and about a hundred other basic rules and specifications required for responsible navigation. There is no provision in the rules of the road for AIS. That may be required (someday) to be an AB, ABYC, or other published safety standard compliant boat, and for all I know, T-Boat certs and above may require that by now, but those day shapes are still very much a thing to professional mariners, and of course international law. Learn them. They are great. Nobody is expecting you to keep a set of signal flags on board, but when you at least learn basic navigation (at least the Colregs!), things like these mystery "radar balls" suddenly get meaning, then you start to notice them everywhere else, and all the sudden you advance from seaman recruit to seaman apprentice.

[avant]

Yes you do.

[Lodesman]

Originally Posted by Aethelwulffe

Those things in the image are only radar reflectors secondarily. Primarily, they are DAY SHAPES. .

Maybe check the annex in the rules you posted:

6. Shapes

(a) Shapes shall be black and of the following sizes

don't paint your reflectors, unless using them as dayshapes.

[StuartWeibel]

A radar reflector is an inexpensive bit of insurance. I carry one and I have AIS as well, and I am pleased to have them. If you are unsure of the effectiveness of a given reflector, why not ask about your visibility from time to time on the radio? I've done this enough to know that my small vessel's radar signature is clearly visible and thus doing its job. The two technologies together give me a high degree of confidence.

[psaltydogs]

Radar reflectors don't work. The cylindrical ones are too good to be true, and they don't work. Small vessels, even steel ones like mine, are invisible to big vessels with radar. If you accept this as the truth in every situation, it will help to protect you from collision. My boat has a radar reflector because they are required in Canada. I thought of putting on a second one, because if one is good, two must be better. But other vessels still won't see me.

[mstrebe]

I was a former Electronic Warfare Technician in the Navy and a current sailboat owner with a Radar who frequently travels the busy shipping lanes of Southern California. I've worked with Radar my entire adult life including reflectors, chaff, and radar jamming.

Here's the deal:

It depends on the size and type of your boat. Any sailboat with an aluminum mast reflects radar just fine. So do sport fishers with a tower and any boat over 30'. Those are all reasonably visible on any pulsed radar and any FMCW radar set made in the past 30 years.

But small console fishing boats 26' and smaller do not show up in even moderate seas. Basically, if the average wave-height is not much lower than your freeboard, a fiberglass boat with no metal topside will be lost in the noise of the sea clutter.

Regardless, a radar reflector is not the correct answer. The correct answer is an AIS transceiver and proper navigation lights. AIS is smaller, more reliable, weighs less, has no maintenance, and is far more useful. It does not depend on the quality of the transmitting radar or the sea-state to operate properly. Anyone with a radar also has an AIS receiver. Anyone without an AIS receiver also does not have a radar.

But Nav lights are the most important of all. I can't tell you how many times I've come up on little sport fishers bobbing 20 miles offshore with no lights on, not moving, no wake, and no consistent radar return and had to steer away at the last minute as my own nav lights reflected off their fiberglass.

Yes, they both require power. If you lose power in the dark on your boat, get your can of air horn out, keep watch all night, and be prepared to blast it at everyone who comes near. You need rescue anyway.

But those idiots aren't reading this forum so...

[Talbot]

Something goes wrong and you are involved in a collision in fog, and you do NOT have a radar reflector of some type, you can bet that the other side will get a non-maritime judge to understand the requirements of SOLAS and you will be at fault regardless of actual actions at the time.

As for effective radar reflectors The lens type work extremely well, but not in all circumstances. A yacht heeled over is not their strong point.
The narrow tubes are marginally better than wrapping a broom handle in foil!
The large diameter cylinders are expensive but not very esthetically pleasing However, they are the most effective. Furthermore, you need to mount them as high as possible to cope with deep wave blanking of the radar signal.