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Old 24-07-2008, 04:59   #1
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Do Radars Fry your Brains?

I had an interesting conversation today with my coxwains teacher, he said the position of the radar dome is very important, as it can do damage to us humans.

Anyone have any thoughts on this?

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Old 24-07-2008, 05:17   #2
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Marine RADAR systems operate in the high radio frequency (RF) and microwave range. Unlike X-rays and nuclear radiation the emissions are non-ionising radiation and do not penetrate the human body, but can cause heating of the surface, particularly of the skin and eyes (cornea).

The only proven biological injury from RADAR is the result of its very short wavelength radio waves, commonly called microwaves. Like microwave ovens, high exposures to RADAR emissions cause heating in exposed tissue. If the heating is sufficient, the tissue dies. Normal blood flow provides cooling, so long exposures in very close proximity to radar emissions are usually required for significant injury. Exceptions to this are the eyes and testes, where blood-flow cooling is weak.

There have been several claims of other biological injuries from microwaves, including induction of cancer. However, none of these have been confirmed by independent research.

Don't mount your radome in any location that will expose crew to RF, especially long-term and near exposures. The RADAR signal travels in a more or less horizontal pattern.Mounting the antenna atat least five feet above anyone’s head should satisfy radiation safety concerns.

The International Commission on Non-Ionizing Radiation Protection, and others, have published guidance on exposure to non-ionising radiation.

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Old 24-07-2008, 05:34   #3

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... and be courteous.

It's a good idea to turn radars off while at the dock, in an anchorage or on mooring.

Of course, it's not cruising sailors that keep them on for hours after they arrive... it's usually a large power vessel.
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Old 24-07-2008, 05:51   #4
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Are Microwaves Hazardous?
They can be if the intensity is sufficiently high. Microwaves are absorbed by living tissue and their energy is converted to heat that may easily damage some organs, particularly the eyes, which may develop cataracts. It has also been shown that long-term exposure to low levels of microwave radiation can induce a variety of physiological effects in small laboratory animals. The importance of these effects and their relevance to the case of human exposure are not yet fully understood. Microwaves may also interfere with cardiac pacemakers.

The maximum safe levels of exposure to microwaves are specified by the ARPANSA Radiation Protection Standard - "Maximum exposure levels to radiofrequency fields - 3kHz to 300GHz" Persons on or about the craft, other than personnel specifically involved in the installation or maintenance of the radar should not be exposed to average levels higher than 10 W/m2 or to peak levels exceeding 10,000 W/m2.

What are the Radiation Levels Associated with these Radars?
Obviously they vary according to the particular make and model. However, calculations based on information supplied by the manufacturers and measurements carried out by this and other laboratories(1) indicate that at 1 metre from, and at the same height as the antenna, peak levels of approximately 0.5 W/cm2 may be encountered. The average intensity may be between 0.5 and 0.8 mW/cm2, when the antenna is stationary. The average intensity drops to safe levels (i.e. below 0.2 mW/cm2) at a distance of several metres from the antenna. At points above or below the horizontal plane containing the antenna, the radiation level is lower than that measured at a corresponding point on that plane. However, it must be noted that the radar has a rather large vertical beamwidth, i.e. microwave radiation is beamed also above and below the horizontal plane. This allows the radar to track obstacles on the water surface even during strong rolling movement of the vessel. At 1.5 metres from the antenna and 50 cm below the antenna level, the average intensity can still be in excess of the 0.2 mW/cm1 limit.

During normal operation the average exposure is reduced, because the radar antenna rotates and a person is exposed only when the beam sweeps past.(See footnote 1) For example, a person standing one metre away from a 1.2 m (4') rotating antenna is exposed to less than 20% of the average radiation level in the beam.

Safe Practice
Exposures to microwave radiation above the recommended limits are most likely in the immediate vicinity of the antenna when it is stationary. When the antenna is rotating, as required for normal operation of the radar, average exposure is below the recommended limits, even at points as close as one metre.

Some radars are designed to prevent microwave emission unless the antenna is rotating. Other models, however, lack this safety feature. In these cases some care is required on the part of the operator to prevent unnecessary exposure of personnel. Operating procedures should be adopted which ensure that no microwave radiation is emitted except when the antenna is rotating.

A rule of good practice which applies to all small marine radars is that equipment should be turned off when not required, particularly in areas of high population density (e.g. at dockside).

Note: Also put a sign..."Man up mast" beside Radar controls if you plan on climbing up there
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Old 24-07-2008, 06:12   #5
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I love the radars that are mounted on the cabin top right in front of the flybridge.

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Old 24-07-2008, 06:13   #6
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The COE lockmasters along the Mississippi River in New Orleans will tell operators to turn off their radars before entering the lock.
Once I did see a large CG vessel at dock, people were up in the vicinity (close) of a huge open array antenna which was rotating, seemed strange maybe the transmitter was off, just the antenna rotating?
I don't own a radar yet my brain has been fried for some time now!
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Old 24-07-2008, 16:39   #7
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One of the first studies was in 1978 showing the effects of radiation from power lines on the incidence of leukaemia in children. This has largely since been supported by other research and accepted by the ICNIRP referred to.
It is true that research on concerns about such things as cell phones and their towers and the effects on health have shown mixed or inconclusive results.
However this needs to be viewed in the light of some of the difficulties of doing such research.
1. there are ethical difficulties in experimenting on humans to see what doses they can withstand.
2. Gross manifestations ie those easily detected and measured, eg brain tumours occur naturally at a low rate and may take a considerable time to become evident. This means that very large subject groups must be followed for very long periods.
3. This introduces a cost problem as funding would be difficult to obtain. There is also in the publish or perish industry a desire for results which can be obtained quickly at limited cost and published preferably with significant results.
4. Consequently many studies are small budget and scale with limited controls, scope, and duration. That they lack the power to detect significant results is no surprise to more sophisticated researchers, however the negative results are often misinterpreted as correctly showing no effect, rather than being inadequate investigations.
5. As many studies are not truely experimental the results can only show correlation which is not proof of causation. They then can be criticised as not providing proof. However they can be suggestive.
6. There is considerable difficulty in defining the quasi experimental and control groups, eg specifying what their actual exposure was for what time versus other sources, and that they are otherwise matched. For example how long did children live under high tension powerlines and does that also mean that they were from poorer households with other complicating factors.
I understand that there is considerable variation between countries in relation to various safety standards.
Without going into detailed technical arguments on a practical level one might be prudent to limit exposure as much as practicable, by height and limiting use.
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Old 24-07-2008, 17:28   #8
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I guess then that the takeaway is that I should have the radar installed up the mast rather than on a transom post. Any issues re fast approaching boats from astern with such an arrangement?
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Old 24-07-2008, 21:59   #9
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Regarding radiation and the human body...

When I was in the Navy, we took great care to stand clear of ANY radar!

Has everyone seen the latest...
PITTSBURGH, Pennsylvania (AP) -- The head of a prominent cancer research institute issued an unprecedented warning to his faculty and staff Wednesday: Limit cell phone use because of the possible risk of cancer.
Cancer expert warns employees on cell phones -

FDA says cell phones are OK, but research says no... Who ya gonna believe???

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Old 24-07-2008, 23:18   #10
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By what possible mechanism can a microwave cause a cancer? They're too big by many orders of magnitude. Radar waves are even bigger.

Worried about heat? Are we kidding? We're sailors. We spend the equivalent of years in the Sun, a source of UV waves, which actually are small enough to cause a cancer.

Originally Posted by cnn
Still, Herberman cites a "growing body of literature linking long-term cell phone use to possible adverse health effects including cancer."
This is NOT "the research". The FDA, and the research both say no. The scientifically astute wonder why Haberman's 'growing body of literature' isn't taking the form of an actual peer-reviewed meta study.
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Old 24-07-2008, 23:55   #11
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I used to be tuna spotter and if any one turned on the radar I could immediately feel a [particular nausea . I wolud notice the nausea first before seeing the radar being on.
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Old 25-07-2008, 00:15   #12
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When I was in Navy here in Aust, there were (still would be) very strict rules about going aloft. You would have to get all the keys to the various antenna (HF Radio, Radar, Missile guidance radar, Electronic warfare equip) so they could not be operated before climbing aloft - would even have to get them from other ships if close by.

At sea you would not be allowed on deck aft of the bridge if the missile guidance radar was operating. If you have seen any video of warships at sea you may have seen some interference to the picture & a funny sound every few seconds as the radar beam goes past - very dangerous stuff....

Once had a green peace protester stowaway on our ship hiding very high on the TACAN platform (aircraft navigation system) and came down a day or so after being at sea - he was dead a few months later..

Small vessel stuff is obviously less powerful, but I think exposure over a long period of time would have some detremntal effect on ones health...
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Old 25-07-2008, 04:34   #13
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They Ain't Called "Radar Ranges" for No Reason!

During my tour in Viet Nam (1965-66) for awhile we operated out of a compound in Ca Mau, in IV Corp, that had a sizable radar installation. Once in awhile the Zoomies that ran the thing would crawl up and hang a sandbag from the center cone of the dish for a few sweeps. It seems that one fellow's mother would deep freeze Nathan's Hot Dogs and rolls and would send them to him in heavily insulated packages. Placed in the sandbag, three sweeps made for quite warm, 6 sweeps for pretty hot, 9 sweeps for blazing etc.

On one occasion Charles decided to lob some 82mm into the position while a bag was hanging on the dish and of course it was forgotten in the ensuing melay--at least until the cotents exploded--which was subsequently reported as a morter hit to the dish by a Zoomie Bird that didn't realize what was up.

I would judge that one should avoid exposure to the beam...

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Old 25-07-2008, 06:22   #14
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Originally Posted by anotherT34C View Post
By what possible mechanism can a microwave cause a cancer? They're too big by many orders of magnitude. Radar waves are even bigger.

Worried about heat? Are we kidding? We're sailors. We spend the equivalent of years in the Sun, a source of UV waves, which actually are small enough to cause a cancer.
UV doesn't penetrate the skin to a great depth - and we know it causes damage; prudent sailors recognize this hazard and take steps to protect against it. Microwaves penetrate deep into the body, where they heat the tissues. It is highly debatable that this would ever cause cancer, but whether it does or not, common-sense would rule that "cooking" ones internal tissues, especially the brain cannot be a good thing.
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Old 25-07-2008, 07:17   #15
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Originally Posted by chris_gee View Post
One of the first studies was in 1978 showing the effects of radiation from power lines on the incidence of leukaemia in children. This has largely since been supported by other research and accepted by the ICNIRP referred to...
Interesting speculation, but I'm having trouble understanding how this relates to the question about radars.

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