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Old 13-02-2013, 13:18   #46
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Re: Radar Reflector Review,to Have or Not to Have?

I believe my SeaMe presents a 60m3 surface area when painted by a radar, which is far, far beyond the 8m3 of the most expensive, big tri-lens. I bought it for less than a boat-dollar and it is the best thing you can buy when going to fog-prone areas besides a good radar... which I also bought.

My only problem is that we're not going to that fog anymore because we changed our plans


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Old 13-02-2013, 13:53   #47
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Re: Radar Reflector Review,to Have or Not to Have?

http://www.toerzeilers.nl/documentat..._juni_2012.pdf

a link to a test of reflectors
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Old 13-02-2013, 14:29   #48
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Re: radar reflector review,to have or not to have?

Take a look at the tests that the reflectors failed. THe test refers to IMO Resolution MSC. 164(78) which sets the standard for the tests. To quote in part:

3.1 The radar reflector should have a “Stated Performance Level” measured in square metres
radar cross section (m2 RCS) of at least 7.5 m2 in X-band and 0.5 m2 in S-band mounted at a
minimum height of 4 m above water level.

Now I don't know about you but 7.5 m2 is a large surface area.

When you compare the surface area of a mast to that of a reflector you are mixing apples and oranges. The surface area of the mast that can be counted is the portion that returns a signal to the transmitting antenna. Only that part has a direct return signal. The rest of the mast is reflecting only by scatter.

Lastly, because the reflectors do not meet ISO8729 and thus IMO Resolution MSC. 164(78) it does not mean that they are ineffective. It just means that they do not meet the (a SOLAS) standard. They still increase your radar footprint and may save your life.

Regards

PS here is a link to the actual Maib testing

http://www.maib.gov.uk/cms_resources...s%20report.pdf
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Old 14-02-2013, 03:01   #49
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Re: Radar Reflector Review,to Have or Not to Have?

Now that the OP's OP has been resolved it's time to say that there is a lot of Horsepoo in this thread. Clearly some posters have no idea of how radar (radio) waves work.

Very simply put, the radar signal has to be reflected back to the radar antenna (scanner). It is similar to the way light needs to be reflected back to your eyes if you want see something in the dark when using a torch (flashlight)

A metal mast doesn't do this. Well it might if it is vertical but once heeled over, it doesn't. Simple physics. However a good radar reflector will reflect some of the signal back.

Using the light analogy for a moment, a radar reflector to radar waves is somewhat like retro-reflective tape is to light.

But if you don't want to believe me, read what radar knowledgeable people say:
The Radar Reflector Site
In particular http://www.theradarreflectorsite.org...tedByRadar.pdf and http://www.theradarreflectorsite.org...tedByRadar.pdf

or
Corner reflector - Wikipedia, the free encyclopedia
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Old 14-02-2013, 03:13   #50
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Re: Radar Reflector Review,to Have or Not to Have?

Still not convinced!

Last year the Australian Navy bought a good supply of Plastimo Octahedral reflectors and gave them to Indonesian fishing boats (wooden vessels) that were operating legally in the waters between the NW Aussie coast and Indonesia.

The naval vessels had significant movements in this area (due to foreign people smuggling activities) and wanted to be sure that the Indonesian fishing vessels were radar visible.

Of course the navy might know jack about radar .
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Old 14-02-2013, 06:50   #51
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Still not convinced!

Last year the Australian Navy bought a good supply of Plastimo Octahedral reflectors and gave them to Indonesian fishing boats (wooden vessels) that were operating legally in the waters between the NW Aussie coast and Indonesia.

The naval vessels had significant movements in this area (due to foreign people smuggling activities) and wanted to be sure that the Indonesian fishing vessels were radar visible.

Of course the navy might know jack about radar .
And not likely to be providing them with batteries and Seamee active reesponders. Anything better than nothing. And high quality radar and operatives searching is different from normal commercial traffic I would guess.
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Old 14-02-2013, 07:08   #52
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Re: Radar Reflector Review,to Have or Not to Have?

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And not likely to be providing them with batteries and Seamee active reesponders. Anything better than nothing. And high quality radar and operatives searching is different from normal commercial traffic I would guess.
I guess so (and gives the friendlies a different radar signature from the others)
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Old 14-02-2013, 07:43   #53
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Re: Radar Reflector Review,to Have or Not to Have?

I've always been impressed how well offshore fish traps and floats show up on our radar (24" antenna) with small trihedral reflectors (maybe 10"?) at the top of an 8 foot pole. We routinely detect them a few miles away. Detection range and success for sailboats is less consistent - sometimes many miles and sometimes inside a mile.
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Old 14-02-2013, 08:41   #54
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Re: Radar Reflector Review,to Have or Not to Have?

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Originally Posted by cfarrar View Post
I've always been impressed how well offshore fish traps and floats show up on our radar (24" antenna) with small trihedral reflectors (maybe 10"?) at the top of an 8 foot pole. We routinely detect them a few miles away. Detection range and success for sailboats is less consistent - sometimes many miles and sometimes inside a mile.
Most of my offshore commercial fishing customers use radar reflectors. These are for eel traps set way offshore. The boat is a "Deadliest Catch" style 80 footer..

One thing I can assure folks of is that these fishermen WILL NOT spend money on anything that "does not work"...... That's about $30.00 per buoy in added cost..... But yeah, "I read a study, and they don't work."....
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Old 14-02-2013, 08:59   #55
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Re: Radar Reflector Review,to Have or Not to Have?

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That is not the catch rain position. The horizontal plates do absolutely nothing.


I understand and agree with your advice; however, I am likely to leave it as it is. You'll notice the photos of the fisherman's bouys in the post above and see that they are also positioned as mine. These, in this position, present a great display on radar screens, as mine does. Once again, your advice is sound, but likely not significant in the conditions that are met in my cruising experience.
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Old 14-02-2013, 12:15   #56
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Re: Radar Reflector Review,to Have or Not to Have?

Thank you Wotname and EVM1024 for inserting some important points about the reality of radio wave reflection off tilted masts vs corner reflectors and the fact that failure to meet a stringent standard doesn't mean that they don't do a great job!

Mainsail's practical experience and photo proof show that you guys are right on the money.
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Old 14-02-2013, 12:25   #57
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Re: Radar Reflector Review,to Have or Not to Have?

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Originally Posted by Maine Sail View Post
Most of my offshore commercial fishing customers use radar reflectors. These are for eel traps set way offshore. The boat is a "Deadliest Catch" style 80 footer..

One thing I can assure folks of is that these fishermen WILL NOT spend money on anything that "does not work"...... That's about $30.00 per buoy in added cost..... But yeah, "I read a study, and they don't work."....

*SNAPS*
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Old 14-02-2013, 12:49   #58
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Re: Radar Reflector Review,to Have or Not to Have?

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Thank you Wotname and EVM1024 for inserting some important points about the reality of radio wave reflection off tilted masts vs corner reflectors and the fact that failure to meet a stringent standard doesn't mean that they don't do a great job!

Mainsail's practical experience and photo proof show that you guys are right on the money.

This is really true. The specs are SOLAS standards. Take SOLAS vs USCG spec flares. One could hardly argue that USCG spec flares are useless. SOLAS are much better of course but Useless?

On another parallel. Could one argue that a glass that does not have a full pint in it is useless for Ale?
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Old 14-02-2013, 13:34   #59
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Re: Radar Reflector Review,to Have or Not to Have?

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This is really true. The specs are SOLAS standards. Take SOLAS vs USCG spec flares. One could hardly argue that USCG spec flares are useless. SOLAS are much better of course but Useless?

On another parallel. Could one argue that a glass that does not have a full pint in it is useless for Ale?
Yep - great metaphor.

I tell my students that using a DR is the worst method of determining where you are, but it beats doing nothing.
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Old 14-02-2013, 13:38   #60
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Re: Radar Reflector Review,to Have or Not to Have?

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Could one argue that a glass that does not have a full pint in it is useless for Ale?
By the same token, I would argue that drinking ale out of a teacup is a bit silly.

I think we'll all agree that a container ship doesn't need a radar reflector. By the same token, we might also agree that the smaller the boat, the more important the reflector. This is where Mainsail's argument about the reflectors being added to fishing buoys looses its persuasiveness. The reflector adds considerably to the surface area of the buoy itself. Right?

Put that same reflector on my 46 foot sloop, and I doubt you'll notice a gain in reflectance. Not only do I have large topsides, but above the coaming I have a solar bimini built of 1.5" stainless tubing; a stainless traveler arch; an aluminum wind generator on its own aluminum mast; a permanently mounted stainless BBQ; davits holding a 10' RIB with a 15hp outboard and a lead starting battery; a huge mass of metal on the bow associated with anchoring, including 300' of chain above the water line, a double anchor roller holding a monster Rocna, and a horizontal windlass; stainless pushpit, bow pulpit and stancheons; six large winches; a solid vang (aluminum); and an antique bronze bell. Oh yeah, there's also that mast thingy.

That's a lot of target.
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