radar reflectors

What's the reason that most boats like ours do not have radar reflectors. Is it because there is more mass higher above the water providing a larger target, so not as necessary or because of the lack of a good location to put it.?

Probably. Don't forget that most of our boats have a lot of metal in them from engines and generators that are usually at least partially above the waterline to metal masts and booms on many boats to outboard motors on our dinghies, galley stoves, hot water heaters some of which, like ours, are completely above the waterline, the propane tanks in the locker on the flying bridge, and so on.

Our radar can "see" thing like birds that happen to fly through the beam to the six-inch or so fender washers that are part of a lot of the commercial crab pot float rigs around here. This is assuming the water is calm. Compared to those things our boat is the USS Nimitz in terms of its radar reflectivity.

We have a radar reflector on the port mast stay of our boat but I'd be willing to bet that if we took it down it would not make one bit of difference to the radar return from our boat.

I have one one the round Davis reflectors wired under the radar mount on the mast. Like Marin I doubt it makes much difference but it is not in the way or causing me any problem so I'll leave it there.

Our reflector is a Davis, too. It's position puts it out of the way and we installed it on the premise that "it can't hurt and it might help."

Being a steel boat with lots of ninety-degree angles, the Coot is a radar reflector.

markpierce said:

Being a steel boat with lots of ninety-degree angles, the Coot is a radar reflector.

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Yes, I would think the Coot shows up on radar displays like one of the Golden Gate Bridge piers. With all the traffic in the Bay this would seem to be a real advantage on foggy days.

You should have one.
In high traffic areas, to be in compliance with the rules, you not only have to own one, you have to have it properly mounted where it can be "seen" by other boats' radar.

So, to answer the OP's question: ignorance.

Your radar reflector is that big hunk(s) of metal in your engine room.

Keith:

Not always. On a trip through fog, in a line of 6 boats (we were traveling together, so all going the same speed, some of us didn't have radar, so we were staying close enough to see the boat ahead) we were called by a passing fisherman who graded the quality of the return he got from each of us as he approached and passed us. One boat, the one with the most cast iron in the bilges, gave him no return until he could see it visually. The others, as you might expect, showed up according to the quality and position of the radar reflector.

Our boat originally had a wood mast and boom but was replaced with a steel mast with a platform for the radar, I thought this would suffice. I'll have to get some one to try and see me so I know for sure.

Keith said:

Your radar reflector is that big hunk(s) of metal in your engine room.

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Which in most of our boats is below the water line...

I once had a "light boat" captain working the Baton Rouge area tell me that the "plastic" boats without radar reflectors were difficult to see in the fog, even with his commercial radar unit.

The "best " I have tested , (with my VP pals and a damn good radar ), is the old WWII collapsible units for life rafts.

These are only a few bucks each (when they can be found) and will last for a few months if always left up.

Mount high and you can be seen for close to 200 miles! Or at least to the edge range of a waterborne radar.

Great insurance for Maineaic cruisers ,
where amateurs will be operating in fog after reading DA Book that came with their new toy..

koliver said:

You should have one.
In high traffic areas, to be in compliance with the rules, you not only have to own one, you have to have it properly mounted where it can be "seen" by other boats' radar..

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What rules (link please) would those be?

What rules (link please) would those be? __________________
Ron

I knew you would ask. I am presently thousands of miles from my boat, where I keep all of the materials given to me when I trained for the CCGA Courtesy Examinations (now RCM-SAR CE) which include the Colregs and some Coast Guard stuff. I don't want to try quoting from memory, and I can't look it up from where I am now (Palm Desert, CA enjoying the sun and warm temps).
You may have different rules where you boat on the right coast, but where I boat, RR is a "must have". Without one, no annual sticker to show that you comply with all the current rules.

I suggest that everyone who thinks they have a good radar signature check it out for real. I am often amazed at how even relatively large fiberglass vessels can still have a very weak signature. Our 64 mile Furuno radar is great yet these "stealth" vessels sometimes are there with next to no signature. After a near collision in thick fog at the entrance to the Narragansett some years back I fitted a reflector and a very loud air horn with automatic fog signaller. I fitted a large Trilens on the mast. The Trilens is reported to be the best passive reflector but "active" units are reported to be better. Some reflectors are not worth the space they take up (there is very good UK report from MAFFI). As I see it being seen on another vessel's radar is cheap insurance. Yes, we also have AIS!!

International Collision Regulations Rule 40 - A vessel that is less than 20 metres in length or is constructed primarily of non-metallic materials shall be equipped with a passive radar reflector.

koliver said:

What rules (link please) would those be? __________________
Ron

I knew you would ask. I am presently thousands of miles from my boat, where I keep all of the materials given to me when I trained for the CCGA Courtesy Examinations (now RCM-SAR CE) which include the Colregs and some Coast Guard stuff. I don't want to try quoting from memory, and I can't look it up from where I am now (Palm Desert, CA enjoying the sun and warm temps).
You may have different rules where you boat on the right coast, but where I boat, RR is a "must have". Without one, no annual sticker to show that you comply with all the current rules.

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I get a Coast Guard Auxilliary safety inspection every year and radar reflectors have never been mentioned. I will say this though; Runabouts, center consoles, and sport cruisers don't typically come from the factory with radar reflectors and I don't recall ever seeing on that's been added to one of these boats.

The previous owner of my boat left a folding radar reflector on it, but I've never used it.

Chrisjs said:

As I see it being seen on another vessel's radar is cheap insurance. Yes, we also have AIS!!

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Very good idea.

Previous owner installed a cylindrical device on the mast. I have never asked anyone if it improves my "signature" .. then again, I can only recall two times we were out in conditions of really low visibility.

boatpoker said:

International Collision Regulations Rule 40 - A vessel that is less than 20 metres in length or is constructed primarily of non-metallic materials shall be equipped with a passive radar reflector.

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OK. According to a random website conversion program, that's sixty-five feet, seven and one-third inches. At 31' LOA, I'm well under that requirement. Actually, I don't know anyone with a boat that big.

edit: Opps, my bad!

rwidman said:

OK. According to a random website conversion program, that's sixty-five feet, seven and one-third inches. At 31' LOA, I'm well under that requirement. Actually, I don't know anyone with a boat that big.

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Every boat under 20 metres regardless of build material is required to have a reflector under that rule. (there are a few exceptions ... canoes etc.).

boatpoker said:

Every boat under 20 metres regardless of build material is required to have a reflector under that rule. (there are a few exceptions ... canoes etc.).

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You're right, I read it wrong. Still, the vast majority of these boats don't have radar reflectors. and the Coast Guard Auxilliary has never mentioned it. I don't believe it's on their printed checklist.

So what now? Everyone on the river gets a citation? The guy pulling his kids in a runabout? The guy in the 18' CC fishing near the bridge? The bunch partying at the sandbar?

rwidman said:

You're right, I read it wrong. Still, the vast majority of these boats don't have radar reflectors. and the Coast Guard Auxilliary has never mentioned it. I don't believe it's on their printed checklist.

So what now? Everyone on the river gets a citation? The guy pulling his kids in a runabout? The guy in the 18' CC fishing near the bridge? The bunch partying at the sandbar?

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There are exceptions, you'd have to read the whole thing but essentially if you are in an area where radar is commonly used, underway between dusk or dawn or in "unfavourable environmental conditions" near traffic patterns .... should should have one.

I've done a number of tests over the years and have found as other posts suggested that some boats due to shape, material or sea conditions can disappear from my 5kw radar for long periods of time. I once nearly ran over a 30' Police RIB in heavy fog. He was not sounding the appropriate signal and did not have a reflector. Too bad I didn,t hit him, I could have retired on the proceeds.

I believe rule 40 as stated is a Canadian rule only (says Canadian Additional) right in their rules.

I don't see a rule 40 in eithe US or The IMO rules....could be wrong...but couldn't find it in either of those.

And yes a good idea if your RADAR signature stinks.

psneeld said:

I believe rule 40 as stated is a Canadian rule only (says Canadian Additional) right in their rules.

I don't see a rule 40 in eithe US or The IMO rules....could be wrong...but couldn't find it in either of those.

And yes a good idea if your RADAR signature stinks.

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Yes, sorry rule 40 is the Canadian version. I believe you'll find the IMO version at Annex Res A.384(x). There isn't much difference. Nothing is US rules. Given the cost, I have never been without one.

boatpoker said:

.......... Given the cost, I have never been without one.

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I have a folding one, just no good place to mount it.

A lot of the Davis radar reflectors I see on boats are mounted wrong. Davis describes the correct mounting as "Catch Rain".
Many years ago Practical Sailor Magazine did a test of a bunch of different radar reflectors (RR). The cheap foil covered Davis gave the best return. Their aluminum RR came in second. Their returns were much better than all of the much more expensive RRs.
Here is a link to a Davis publication that discusses RRs: http://www.davisnet.com/product_documents/marine/manuals/00155-010_IM_00152_153_157.pdf

We have a Mobbri radar reflector mounted on our radar arch and it does give a good radar "bounce." It was made in Denmark and uses aluminum elements arranged at 45 degs. and 22.5 degs to one another inside a plastic cylinder 500 mms long.

For those that don't want to mount a RADAR reflector lining the inside of your flybridge fairing (if u have one) can be as good or better (especially if the foil is crinkled and not smooth) than a commercial reflector.

Many of the tube type have failed tests miserably when they first came out...if you have one make sure you get a couple good checks on it if you are counting on it.