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Old 14-02-2013, 13:44   #61
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Re: Radar Reflector Review,to Have or Not to Have?

why not try it out with a friends' boat that has radar?
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Old 14-02-2013, 13:52   #62
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Re: Radar Reflector Review,to Have or Not to Have?

I sailed up to Maine and back a couple of years ago with a cheap Davis Echomaster reflector in the catch-rain position and an AIS receiver.

Spent a good bit of time on the VHF in thick fog (including sailing into New York harbor). Commercial ships seemed to be able to track me very clearly from several miles away.

Plus one for the cheap radar reflector.
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Old 14-02-2013, 14:05   #63
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Re: Radar Reflector Review,to Have or Not to Have?

Bash

All of those rounded surfaces are simply going to scatter any radar beam. Some, but not much, may reflect back.

Almost everything you mention is close to the waterline. Radar reflectors should be mounted as high as possible.

In Canada, they are required:

Quote:
Radar reflectors are required for boats under 20 m (65’7”) and boats that are built of mostly non-metallic materials. A radar reflector is not required if:

the boat operates in limited traffic conditions, daylight and favourable environmental conditions, and where having a radar reflector is not essential to the boat’s safety; or
the small size of the boat or its operation away from radar navigation makes having a radar reflector impracticable.
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Old 14-02-2013, 14:16   #64
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Re: Radar Reflector Review,to Have or Not to Have?

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Originally Posted by jackdale View Post

In Canada, they are required:
I've certainly heard of Canada. You folks have interesting laws. I'm told that in British Columbia, it's illegal to kill a Sasquatch.
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Old 14-02-2013, 14:45   #65
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Re: Radar Reflector Review,to Have or Not to Have?

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Originally Posted by Bash View Post
I've certainly heard of Canada. You folks have interesting laws. I'm told that in British Columbia, it's illegal to kill a Sasquatch.
In BC it is illegal to kill any mythical creature.

In your state apparently:

It is a misdemeanor to shoot at any kind of game from a moving vehicle, unless the target is a whale.
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Old 14-02-2013, 15:46   #66
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Re: Radar Reflector Review,to Have or Not to Have?

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Originally Posted by evm1024 View Post
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?

Agreed (totally)

On another parallel. Could one argue that a glass that does not have a full pint in it is useless for Ale?
Disagree (totally)

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Originally Posted by Bash View Post
...............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.
As jackdale has posted, your metal items are more likely to scatter than return radar. Please read this link http://www.theradarreflectorsite.org...tedByRadar.pdf

Quote:
Originally Posted by s/v Jedi View Post
why not try it out with a friends' boat that has radar?
Exactly, very good advice

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Originally Posted by jackdale View Post
That is not the catch rain position. The horizontal plates do absolutely nothing.

Interestedly there are some instances when edge on and double catch water are better. Have a look at the diagrams of returns in this link (especially page 4).
http://www.theradarreflectorsite.org...PassiveRTE.pdf
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Old 14-02-2013, 17:28   #67
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Re: Radar Reflector Review,to Have or Not to Have?

Relief holes will allow caught water to drain, FWIW without sacrificing much in performance.
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Old 14-02-2013, 20:25   #68
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Re: Radar Reflector Review,to Have or Not to Have?

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Relief holes will allow caught water to drain, FWIW without sacrificing much in performance.
There is a hole at the centre through which the halyard line is fed. The only time I had one chafe was the result of a clam shell in the reflector. Damn gulls.
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Old 14-02-2013, 20:55   #69
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Re: Radar Reflector Review,to Have or Not to Have?

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Originally Posted by stevensuf View Post
They did tests in one of the uk yachting mags im sure googling will find it, but most of the passive ones returned fairly weak signals, the biggger drum style plastimo ones almost met the iso standard ie the best was a just fail.

I agree with he fog around Gibraltar, twice got caught in it for almost a full day once, spanish coastguard appeared out of nowhere, **** a brick, large motorboat as well , never heard a thing, bloody stealth mode.

About the only time so far i really wished i had radar.

Bet they had you on radar whilst stalking.
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Old 14-02-2013, 21:19   #70
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Re: Radar Reflector Review,to Have or Not to Have?

I have spoken to ships and tugs at sea a few times and asked if they saw me on radar. In a boat with a 45' aluminum mast I was frequently told no until we got quite close.

Once in the Straights of FL on a very rough night I was talking to a couple of tugs pulling a long train of barges. At a mile, our nearest point of approach neither could pick me out of the sea clutter on radar, even playing with their settings. The round section of an aluminum mast just doesn't reflect the signal back to the radar transmitter/receiver.

I jury rigged a reflector with some foil from the galley, duct tape and a couple of boxes and they picked up up over 4 miles away.
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Old 14-02-2013, 21:45   #71
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Re: Radar Reflector Review,to Have or Not to Have?

A few miles east of my location is Tyndal Air Force Base and a contiguous off shore missile test range. Any vessel in the range must be able to clear the area in 90 minutes if asked to do so.

While sailing through the area on a friends Choey Lee the Air Force radio man hailed the boat, advising a missile firing was scheduled. Upon hearing the estimated time to clear the range was greater than 90 minutes he said, "Captain, do you have a radar reflector deployed?".

The answer was affirmative and the response was, "Captain, please remove the reflector immediately."



And for what it's worth, based on my experience working in a classified career field (Electronic Countermeasures) in the USAF, I'm pretty sure the radar reflectors pictured in this thread are effective.

The main reason being that regardless of orientation, they present two or even three surfaces to the incoming signal that work together to increase the probability that the signal will be reflected directly back toward the incoming signal's direction.

A curved surface perpendicular the the signal will always have one "spot" facing the signal.

A flat surface NOT perpendicular to the signal will never reflect back, think F117 stealth fighter.

If a one square foot metal surface was held facing a ship with radar, it would reflect a signal with a strength greater than any typically equipped sailboat. Regardless of how much mast and stainless arches were present.

It's all about how much surface area is available perpendicular to the incoming signals direction.

Sorry I'm rambling, but put me in the "yes it works" camp.
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Old 15-02-2013, 06:20   #72
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No, it is not about showing surface area perpendicuar to incoming radar beams.

Back to school...

Microwave radio waves (=radar) behave like light, i.e. straight lines, no bends.
They reflect off metal surfaces like light does off mirrors.

Now imagine a beam hitting a radar reflector and see how it bounces around the surfaces before being reflected straight back at the source. Next, turn it a bit for a different entry angle and see that it still gets reflected straight back.

Now imagine a mast and see how that reflects the beam.

Science people, you all learned this in school, use that knowledge
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Old 15-02-2013, 07:12   #73
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Re: Radar Reflector Review,to Have or Not to Have?

I agree with what you say Jedi, except the first sentence.

If a surface directly faces the source, the beam reflects directly back to it.

Also, given that the sum of the angles of a triangle equal 180 degrees, a beam that strikes two surfaces of a reflector describe a very elongated triangle back to the source was well.

The more surface area that accomplishes this, the greater the signal strength.

A round mast could only have a thin line of area facing back to the source, and then only if the boat is upright, not healed. A radar reflector has a greater chance of reflecting a usable signal back to the source because of the triangulation described above.

If you are saying a mast would create a stronger reflection than a radar reflector then I guess I would say maybe not always, with qualifications based on variations of the position of things. And would say I think the reflector is more likely to create a stronger signal than the mast.

This is my opinion, based on an Air Force training school designed to help me understand how to work on equipment used to deceive and defeat radar signals from hostile aircraft and ground based missile sights. I had the highest average grade ever achieved at that year long school in fifteen years, sharing that honor with three other people. Which resulted in being asked to stay and join the faculty.

Not saying I'm right, just saying it's my educated opinion.
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Old 15-02-2013, 07:42   #74
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Quote:
Originally Posted by four winds

If a surface directly faces the source, the beam reflects directly back to it.

A round mast could only have a thin line of area facing back to the source, and then only if the boat is upright, not healed.
Yeah, i did my back of the envelope calcs assuming a vertical mast. Don't do this at home, boys and girls, if you have one hull.
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Old 15-02-2013, 07:42   #75
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Re: Radar Reflector Review,to Have or Not to Have?

Even the really cheap ones work well - they just don't last as long. I have seen and communicated with sailboats that had radar reflectors and showed up on my screen much better than 70+ foot wooden shrimp boats with very large steel outriggers.
If shape and reflection wasn't 'everything' I wonder what they used as their base philosophy when designing stealth technology
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