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Old 19-10-2012, 09:14   #1
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Radar Reflectors

There''s a big question buzzing round as to whether radar reflectors are effective or not, following a recent report from Qinetic.

Seems to me that since the question still remains, it's better to hedge your bets and have something rather than nothing, and at the same time not spend a fortune. So hows this for a cheap and cheerful solution?

Backstay Mount for Octahedral Ra
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Old 19-10-2012, 09:26   #2
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Re: Radar Reflectors

If the angles are exactly 90 degrees and it is made of metal it should work just fine. There will be a lot of debate on whether or not they are necessary. My opinion is that for larger boats they are unnecessary. It certainly does not hurt to put one up, other than a little added windage and the cost.

The best way to be seen is with an AIS transceiver, although the downside to that is the cost and power draw.
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Old 19-10-2012, 09:32   #3
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Re: Radar Reflectors

Some years ago Practical Sailor tested a bunch of radar reflectors and decided that the cheap mylar covered foam one made by Davis was as good as or better than any of the more expensive ones.
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Old 19-10-2012, 09:44   #4
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Re: Radar Reflectors

even crumpled aluminum foil in a tube is good..works great--even better then the traditional ones
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Old 19-10-2012, 09:53   #5
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Re: Radar Reflectors

Hi Zeehag
Yes I remember hearing about that. There was a theory going round, for boats with a hollow wooden mast only, that you could shove a length of crumpled aluminium foil up inside the mast and it would produce a great signal response.
I don't know if it were ever proved though. No good inside an aluminium mast of course, and there aren't many hollow wooden masted boats about.
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Old 19-10-2012, 10:04   #6
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Re: Radar Reflectors

pantha--there are a bunch of around--love my hollow box spruce masts---love to park next to a sloop with tall aluminum masts in lightning... i feel soo safe.....have wood mastheads..lol
i keep my regulation radar reflector on mizzen head, and i keep my radar just 6-8 ft below it. mounted on my hollow box mast at a reinforcing box built into these masts...

always have something with which to light up the sails in darkness....
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Old 19-10-2012, 10:37   #7
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Re: Radar Reflectors

Actually, this Coast Guard report favors a tinfoil hat. See figure 2.

http://www.seagrant.umaine.edu/files...al/05raref.pdf

I've been told my boat left a big echo, so I don't worry about it.
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Old 19-10-2012, 12:29   #8
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Re: Radar Reflectors

Quote:
Originally Posted by panthablue View Post
There''s a big question buzzing round as to whether radar reflectors are effective or not, following a recent report from Qinetic.

Seems to me that since the question still remains, it's better to hedge your bets and have something rather than nothing, and at the same time not spend a fortune. So hows this for a cheap and cheerful solution?

Backstay Mount for Octahedral Ra
There are many good tests of passive radar reflectors (just a few: test 1, test 2, test 3) and they all suggest they are not very effective (on typical sail boats).

Essentially in waves, a boat (small, low freeboard, wooden, little/low rigging) with a poor radar return will probably look like wave, whether it has a passive reflector or not. And a boat (larger, metal, high free board and deck house, large rig) with a good radar profile will look like a target whether it has a reflector or not.

AIS is the number 1 way to be seen (by ships at least) today. An active radar reflector is #2. In my mind a passive radar reflector is a bit like a good luck charm - it can make you feel good but is probably not really doing anything useful.
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Old 19-10-2012, 13:42   #9
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Re: Radar Reflectors

The Tri-Lens (large) has gotten a good write up but is pricey compared to the Davis.
In fact, if cost is a factor, a pair of Davis reflectors on either side of the spreader may be the way to go since all boats roll, pitch, and yaw at sea.

http://www.tri-lens.com/practical_sailor.txt

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Old 19-10-2012, 15:19   #10
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Re: Radar Reflectors

Quote:
Originally Posted by panthablue View Post
--- There was a theory going round, for boats with a hollow wooden mast only, that you could shove a length of crumpled aluminium foil up inside the mast and it would produce a great signal response.
I don't know if it were ever proved though. ---
I think the Pardeys did that and received favorable reports from other vessels regarding their radar signal.

I'm not aware of any scientific reports regarding that though.
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Old 19-10-2012, 15:27   #11
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Re: Radar Reflectors

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Originally Posted by zeehag View Post
--love my hollow box spruce masts---love to park next to a sloop with tall aluminum masts in lightning... i feel soo safe.....have wood mastheads..---
Hi Zee -

Interestingly enough, I read an article quite a few years ago on the wood vs aluminum mast subject. Written by people with various fancy degrees and using terminology that was over my head, they concluded that aluminum masts were slightly less likely to be struck by lightning than wood masts.
The reasoning, as best I remember, had to do with the metal masts having a very slightly better ability to disperse charges building up.

Maybe so, maybe not. Food for thought though.
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Old 20-10-2012, 05:01   #12
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Re: Radar Reflectors

Chaff strips for distorting radar returns are tuned to half the transmitter wavelength....so for most small boat radars for civilians, 15mm strips. For the rest, a list of radar bands here:

Radio Bands and Radar Bands Frequency Chart
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Old 20-10-2012, 07:05   #13
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Re: Radar Reflectors

rsmike--i hear ye, buddy---and i am avoiding everything with a fast and bright light show---hopefully those guardian angels who guided us thru gom in lightning storms will continue to keep watch for a lil bit, yet--we will all know when they go off duty....that stuff is scary...


i do have jumper cables in water from shrouds , just in case....
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Old 20-10-2012, 08:05   #14
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Re: Radar Reflectors

Quote:
Originally Posted by panthablue View Post
There''s a big question buzzing round as to whether radar reflectors are effective or not, following a recent report from Qinetic.

Seems to me that since the question still remains, it's better to hedge your bets and have something rather than nothing, and at the same time not spend a fortune. So hows this for a cheap and cheerful solution?

Backstay Mount for Octahedral Ra
might be weary of it on our boat as the backstay is also our SSB antenna. at present, our backstay is a prescribed length for the tuner to work with, adding something that would be a varable to the resistance might cause issues........
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Old 20-10-2012, 08:13   #15
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pirate Re: Radar Reflectors

2 x 2 litre coke bottles filled with short twists of 'Bacofoil'....
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