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Old 12-11-2017, 07:31 PM   #1
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radar radiation danger

One of the things I did since the picture below was taken was to replace the old Raytheon radar dome with a new Garmin unit. According to the manual, the Garmin dome looks "down" 12.5 degrees, which puts the lower portion of the radiation beam uncomfortably close to anyone steering at the helm on the flying bridge. I could always steer down below when using the radar, but the visibility is better on the flying bridge with a whole lot less engine noise. My questions are:
  • If I purchased a radiation dosimeter at Walmart, would that tell me if a helmsman on my fly bridge is getting dangerously high radiation from the radar?
  • Do you think some thin aluminum on the bimini would significantly reduce the radiation levels?
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Old 12-11-2017, 07:52 PM   #2
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Depending on the wavelength you may try this:



or this



L
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Old 12-11-2017, 08:01 PM   #3
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The radar manual will tell you what the safe distance is from the dome. It's based on the same standard that cell phones follow to minimize brain cooking while talking on the phone.

I think you will find the safe distance is something like 1 meter. So unless you will be hugging your radar dome, it's just not an issue.
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Old 12-11-2017, 08:05 PM   #4
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There should be a spec for how far away from the antenna is safe for people to be. I would start with that.

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Old 12-11-2017, 08:35 PM   #5
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Are you sure it's not a solid state radar? Only reason I am asking is you said it's new and many of the new units are solid state. If it is, it puts out about the same radiation as a cell phone.
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Old 12-11-2017, 09:12 PM   #6
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you should never leave anything as important as your family's health to an internet forum....

but..

The Canadian Coast Guard has a brochure their marine radar that says the safe distance is .2 meters.

http://www.bcmea.com/CMS_Content/HS_..._June_2013.pdf

and....

a beam that is 12 degrees does not reach your helm.
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Old 12-11-2017, 09:34 PM   #7
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If you have the radar on it's probably already poor visibility so you won't lose any by moving to lower helm. You should be a minimum of 1 meter from the center beam of an RD218 and you shouldn't look directly into the beam.

I would guess the mast mount is keeping the beam well above your head.
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Old 12-11-2017, 09:58 PM   #8
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Quote:
Originally Posted by seattleboatguy View Post
...If I purchased a radiation dosimeter at Walmart, would that tell me if a helmsman on my fly bridge is getting dangerously high radiation from the radar?
Not unless you have a super-scary radar that emits x-rays or gamma radiation!
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Old 12-12-2017, 12:11 AM   #9
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Dude! You're in Norfolk VA, home of the worlds largest navel fleet, with cruisers, destroyers ,tankers and assorted aircraft all sporting radar's with who-knows how many kilowatts of power output! I wouldn't worry too much about the health hazards of your little 4kW x-band unit. Just a short trip across the Elizabeth river probably exposes you to more radiation from other radars than yours outputs in a lifetime.
Hell, the microwave you have in your galley is probably almost as much power as a small radar & we'll stand right in front of them nonchalantly waiting for our popcorn to pop!
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Old 12-12-2017, 01:02 AM   #10
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Quote:
Originally Posted by Benthic2 View Post
you should never leave anything as important as your family's health to an internet forum....

but..

The Canadian Coast Guard has a brochure their marine radar that says the safe distance is .2 meters.

http://www.bcmea.com/CMS_Content/HS_..._June_2013.pdf

and....

a beam that is 12 degrees does not reach your helm.
One other piece of information that shouldn't apply but can. The above distance is based on a radar transmitting while rotating. One of the reasons for minimum risk is that it's not in one place long. Now, most radars today will not transmit when stationary, but there have been instances of technicians locking them and testing. If transmitting in a stationary position, the distance is 6 meters. So, just be wary and don't allow that to take place, if your unit will even do it.
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Old 12-12-2017, 01:21 AM   #11
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Furuno actually has more extensive warnings and show distances at which you'd have 10 W/sq meter and 100 W/sq meter. The maximum distance they show 100 W is .5 meter as it varies by radar. However, they show 10 W up to 5.3 meter. They comment that if it's installed at a close distance in front of yout wheelhouse, you may need to halt transmission over a sector of it's revolution. So, variable answers and I would confirm with my radar manufacturer. We have radars of all sizes and shapes and some require 4 times the distance of others.

The table I'm talking about is on page 2 of this document.

http://www.furuno.com/files/Manual/1..._4D_4A-25A.pdf
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Old 12-12-2017, 03:17 AM   #12
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To SBG:
No and no.
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Old 12-12-2017, 05:17 AM   #13
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I run mine only in low visibility such as night or fog. Yours is up on the mast like mine. 12.5 degrees down keeps it well above your head on the bridge helm.
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Old 12-12-2017, 05:49 AM   #14
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This is another pretty good discussion of the subject, written in plain English.

WHO | Electromagnetic fields and public health: radars and human health

According to this, the power density needed to produce known health effects is 1000 Watts/Square meter. The Furuno table posted by bandb lists power densities that are fractions of that threshold.

Bottom line, according to the WHO: for modern marine radars, if you’re not staring into the beam and are a meter or so away from the antenna, the risks are minuscule.

Quoting:

  • To produce any adverse health effect, RF exposure above a threshold level must occur. The known threshold level is the exposure needed to increase tissue temperature by at least 1oC. The very low RF environmental field levels from radar systems cannot cause any significant temperature rise.
  • To date, researchers have not found evidence that multiple exposures to RF fields below threshold levels cause any adverse health effects. No accumulation of damage occurs to tissues from repeated low level RF exposure.
  • At present, there is no substantive evidence that adverse health effects, including cancer, can occur in people exposed to RF levels at or below the limits set by international standards. However, more research is needed to fill certain gaps in knowledge.
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Old 12-12-2017, 05:54 AM   #15
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The Furuno radar techs at manufacturer training for electronic installers answered my specific question about this....

He said your head would get hit by the turning array before you were close enough to do any harm.

The safety warnings are great and way overkill usually because in the case of these small radarrs the warnings can be overkill without affecting the vast majority of practical installations.
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Old 12-12-2017, 06:39 AM   #16
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I was on the Carl Vinson carrier during a tiger cruise. I had to wrap my video camera in foil otherwise horizontal lines appeared at every sweep of the ships radar.
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Old 12-12-2017, 07:16 AM   #17
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To answer the OP, the answer is no, don't worry about it, especially with that radar. Went through this discussion with the Furuno guys when we toyed with the idea of adding a second radar in addition to the 6kw open array unit already on the arch. It's good practice to use it when conditions are clear, as discussed in another thread. That way you can really learn how to use and interpret it when visibility is awful.
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Old 12-12-2017, 07:28 AM   #18
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Quote:
Originally Posted by BandB View Post
Furuno actually has more extensive warnings and show distances at which you'd have 10 W/sq meter and 100 W/sq meter. The maximum distance they show 100 W is .5 meter as it varies by radar. However, they show 10 W up to 5.3 meter. They comment that if it's installed at a close distance in front of yout wheelhouse, you may need to halt transmission over a sector of it's revolution. So, variable answers and I would confirm with my radar manufacturer. We have radars of all sizes and shapes and some require 4 times the distance of others.

The table I'm talking about is on page 2 of this document.

http://www.furuno.com/files/Manual/1..._4D_4A-25A.pdf
That's good information. It sounds like Furuno's manual may be more helpful than the manual that came with my Garmin "GMR 18 HD". One of the interesting things about the Garmin manual is that they first say that the beam is 12.5 degrees above and below horizontal. Later, they say "a radar beam can normally be assumed to spread 25 degrees above and below". It seems a little confusing. Also confusing (to me at least) was the "IEEE C95.1-1992" spec they reference. That 108 page spec never mentions the word "radar". The Garmin manual does say to keep your compass and VHF cables 1 meter from the radar dome, and also to keep your SSB, electronics and cables more than 2 meters from the path of the radar beam.

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Old 12-12-2017, 08:25 AM   #19
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Just to clarify a bit: a dosimeter measures ionizing radiation (basically gamma, xray) which is very high energy. Can actually knock electrons out of orbits. Radar radiation is microwave frequency radio frequency which is no where near enough energy to ionize. Dosimeter won't pick it up.
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Old 12-12-2017, 08:39 AM   #20
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Quote:
Originally Posted by Benthic2 View Post
and....

a beam that is 12 degrees does not reach your helm.
This observation seems to have gotten lost in the ensuing chatter. If you were standing up on your tiptoes way forward near the windscreen with your head touching the forward part of the bimini, you might be in the radar beam. But then you would be about 10 feet away from it.

So your radar installation looks quite safe to me.

David
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