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Old 05-03-2007, 17:34   #1
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RADAR in the marina

Hopefully this isn't too stupid a question. I have heard that turning on radar in the marina was dangerous to passerbys but an internet search gave conflicting opinions. One said that this was an old wife's tale and there was absolutely no danger, another said as long as nobody was standing right in front of the boat and stayed there awhile that it wasn't a problem, yet another seemed that doing so would doom everybody in the marina to a horrible death. Opinions?

I'm doing an offshore class next weekend and wanted to practice using the radar and gps before we went out so it looked like I knew what I was doing
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Old 05-03-2007, 17:54   #2
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This really depends on the radar set in use, but for most civilian small vessel radars a safe distance from the transmitter is 1 metre (3 feet). You don't have to worry about your head exploding if you stray closer than that, but try not to linger about. The radiation is non-ionizing, so you don't have to worry about glowing in the dark, but over-exposure can result in heating (think microwave ovens), the long-term effects on humans are not really known.
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Old 05-03-2007, 18:10   #3
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sans, How low is your array? It must be down on the deck if you are that worried. At that height it is not too practical. So the first thing I would do is get it as high as possible for proper use.
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Old 05-03-2007, 20:24   #4
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Take a chicken wing - put it in front of your radar, turn it on and leave it for fifteen minutes - you'll have your answer.
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Old 05-03-2007, 21:03   #5
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I don't know about cooking a chicken wing. The formulas for field density at various distances from the transmitter are somewhat complex. Suffice it to say, there is an RF field created by the transmitter. Low power units like the ones we use are not particularly dangerous, certainly not beyond a few feet. But you will still be getting nuked, perhaps only a fraction of a watt per revolution at 5 feet. I won't get in the line of an active transmitter closer than 20 feet.

Now the high power radars the military uses are a different story altogether. The surface search radars are not much more powerful than commercial versions. The air search radars are not permitted to be activated in port, let alone the continuous wave illuminators that can fry seagulls that land nearby. The primary effect of radar radiation hitting your body is nothing more than heat. Anecdotally, there may be other issues, but none have been scientifically proven. A good friend of mine was accidentally nuked by an Aegis air search radar. He felt no immediate ill effects, but five years later, he developed a rare blood cancer. He had no family history of this disease, and blames the radar exposure. Of course this can't be proven one way or another, but you won't find me in front of a transmitter. I even buy flip out cell phones.

Brett
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Old 05-03-2007, 23:00   #6
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In intense Microwave energy, the major concern is to the eye. Being filled with mostly fluid, it is very prone to damage. The energy can cause catarachs.
However, for a Radar to cause this much damage, you need to be right up close to the transmitter looking into it. 3ft is considered a safe range for all "civilian" transmitters. But that has a good fudge factor. You can safely get much closer than that, but the 3ft is a good rule.
As already stated, just what long term affects there maybe are simply not known. There are many reports of people under power lines with higer % of cancer than those that don't live under them. There are reports of CellPh's causing tumours. But so far there has been no provable scientific information available that any electromagnetic radiation can or can not cause health issues. If it is ever proven it can, we have major problems to deal with. Your local TV transmitter and radio stations will be putting out more radiation than anything else around you.
You certainly would want to wear lead underwear if you are infront of the big military scanners though.
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Old 06-03-2007, 01:45   #7
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Electromagnetic fields and public health:
Radars and Human Health ~ World Health Organization fact sheet
WHO | Electromagnetic fields and public health: radars and human health
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Old 06-03-2007, 04:52   #8
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I think all have given you good advice - but practically if you do fire up the radar in the marina you are going to get so much clutter from close vessels the screens going to be virtually unreadable.
Good luck with the exam - but suggest this last minute testing might not be of much value.
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Old 06-03-2007, 10:51   #9
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Thanks so much for the great information. This is a 41’ Hunter so I’m sure the radar transmitter is located at least as high as the spreaders, so I’m now not too concerned about running it in the marina. Also how the docks are oriented I will see anybody well before they get to the boat so I’ll just plan on shutting the radar off if anybody is walking down the dock.

You’re right John, I’ll get lots of clutter in the marina but I was mainly wanting to learn the “navigation” of this system; which buttons to push to access which screens. I’ve used many radar systems but it seems that each one is subtly different in its operation. We’ll be leaving in the dark and since I’m already half blind at night, I didn’t want to be fumbling trying to get the #$%^ right screen to display.
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Old 19-10-2008, 15:44   #10
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Are you serious????

I was on watch with an owner of a vessel I was Chief on.

One clear and non-stormy night I noticed him on the wrond side of the channel.

That was when I found out he was colorblind......

I didn't leave the wheel much that nite.


Quote:
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Thanks so much for the great information. Weíll be leaving in the dark and since Iím already half blind at night, I didnít want to be fumbling trying to get the #$%^ right screen to display.
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Old 19-10-2008, 17:06   #11
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Isn't that one reason why Red Markers are Triangular (in the USA) and Green Square? And this person got his coastal piloting training from...?

s/v HyLyte
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Old 19-10-2008, 18:28   #12
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Quote:
Originally Posted by SanSailer View Post
will see anybody well before they get to the boat so Iíll just plan on shutting the radar off if anybody is walking down the dock.

You don't need to bother doing that.

But.......

Give them a hug and if they feel too warm turn your power down.
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Old 20-10-2008, 07:44   #13
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It depends on the radar, but in this case, it's probably just a typical 4kw pulsed radar. The only danger would be to someone looking directly into the antenna from a distance of less than 3 feet. Radar scanners should normally be installed at least 1 foot above eye level for this reason. Your not going to cook anything with this radar. That 4 thousand watts of power is peak power. The average output at the widest pulse length will be less than 2 watts. It's perfectly ok to run your radar in the marina without danger to anyone around. As far as clutter in the marina is concerned, well that's what your STC (sea clutter) is for. I can run the radar's on the Naval Academy sloops in Santee basin and with the STC adjusted right, I can make out the goalposts on the soccer field next door as well as the outline of the Severn river just fine. Depends on how landlocked you are, the terrain, and the height of your scanner.

Eric
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Old 20-10-2008, 08:45   #14
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There are three variables that determine relative safety of EMF, power, distance and frequency.

The more power, the worse.
The greater the distance, the better by a factor of the inverse distance squared.
The higher the frequency, the worse.

I read somewhere you get more EMF exposure by standing in the sun than standing next to typical yacht radar.

I don't worry about it.
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Old 20-10-2008, 11:44   #15
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There are some jobs that just shouldn't go to the color blind. Such as bomb squad, pilot, navigator, etc.
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