Odd Radar Mounting

If I ever see this guy I'll tell him there's a lot of curious guys on TF w some questions.

Looks wobbly.

You guys have it all wrong. The purpose of mounting a radar in the bow pulpit is so they can use it to see if the anchor has dug in well.

It's definitely designed to keep anybody from anchoring near them. I'll bet it works too.

No Mast said:

You guys have it all wrong.

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Probably right.


If Eric manages to get the old boy to sign up and respond to this thread we may all have a new way to mount radomes.

LarryM said:

Mark,

This is an 'apples to oranges' comparison of completely different technology.

A 3G Broadband FMCW (Frequency Modulated Continuous Wave) radar radiates just 0.165 Watts Calculated Average Power. That's about 1/10 the 1.6 watts maximum allowed in the US.

In contrast, a small, Garmin GMR18HD 4KW radar radiates 2.235 Watts Calculated Average Power, about 13.5 times that of the 3G Broadband radar.

The Garmin's average effect is only 2.235 Watts, and that's only if you hug the radome, or about 50% more than your mobile phone (1.6 watts maximum in the US). The radiation is not cumulative. It is microwave radiation, same as from your microwave oven and quite similar to that of your mobile phone, although slightly different frequency. You will pick up more radiation speaking in your mobile phone, sitting too close to an old TV, standing within 3 feet of the microwave or spending a day in the sun than you will from standing next to a 4 kW radar.

It's just not the same thing.

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Larry,
You are not quite right about the 4kw radar. Although the average power is indeed just a few watts, the peak power is 4 kw. That has the capability to damage cells. An analogy might be that you can stand in the rain all day with no damage but the same amount of water falling in a bucket all at once would probably kill you. Also microwave ovens go to great lengths to keep radiation inside the oven by elaborate sealing and gasketing of the door. They are generally about 600 watts and in the same frequency range as radar. Standing in the sun brings up the issue of ionizing versus non-ionizing radiation. Radar is non-ionizing and the jury is still out on just what damage it can do to people but most choose to play it safe where high powers are concerned.

Paul

No Mast said:

You guys have it all wrong. The purpose of mounting a radar in the bow pulpit is so they can use it to see if the anchor has dug in well.

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ok so now that is logical

Paul Swanson said:

Larry,
You are not quite right about the 4kw radar. Although the average power is indeed just a few watts, the peak power is 4 kw. That has the capability to damage cells. An analogy might be that you can stand in the rain all day with no damage but the same amount of water falling in a bucket all at once would probably kill you. Also microwave ovens go to great lengths to keep radiation inside the oven by elaborate sealing and gasketing of the door. They are generally about 600 watts and in the same frequency range as radar. Standing in the sun brings up the issue of ionizing versus non-ionizing radiation. Radar is non-ionizing and the jury is still out on just what damage it can do to people but most choose to play it safe where high powers are concerned.

Paul

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Paul,

That is not my understanding of how RF radiation from radar affects humans. Everything I have ever read or learned in school says that Maximum Average Power is what we are exposed to when we are in near an operating radar.

There is a well written piece entitled "Hazardous to Your Health?" printed in Power & Motoryacht Magazine addresses the current thinking on marine radar safety. I believe it mirrors my original observations.

The World Health Organization published "Electromagnetic fields and public health: Radars and Human Health Fact sheet N°226" which discusses how RF as it relates to public health. It addresses Marine Radar among other sources of RF radiation.

I believe consumer microwave ovens operate at 2.45 GHz and between 600 and 1,100 Watts. The Garmin GMR18 operates at 9.41 GHz with 4,000 Watts of Peak Power but Maximum Average Power of only 2.3 watts. Here is a link to Garmin's FCC Application for the GMR18 Radar where these specifications can be confirmed.

The manufacturers rhetoric is more dismissive of the dangers than it should be yet, every manufacturers instructions contain warnings that advise users to minimize direct exposure to the emissions.

I personally 'choose to play it safe' as you mentioned.

From my factory training as a field tech from Raymarine, Furuno, and Simrad.....

The answers about radiation exposure were all the same...don't be stupid..but none will harm you.

The 4 kw , unless you can get it to be on and non pulsing and non rotating (a rare combination)..... the dosage is for only a fraction of the time....

Much like a microwave on defrost or ultra low power setting where the microwaves are only generated in very small bursts.

If that radar is set up with a dead zome where the rest of the boat is like in many of these installs that are body level...there is even less radiation as it would only be scatter back.

You are probably getting more radiation from the sportfish that comes back to his slip with his 25kw bird finding radar still on to look cool.

The owner of the marine elecronics shop where we have purchased all the electronics for both our US boats told me that the only way one could be in danger from the radiation from a typical recreational boat radar like a Furuno would be to hold one's head against the radome of an operating radome for a week.

Marin said:

The owner of the marine elecronics shop where we have purchased all the electronics for both our US boats told me that the only way one could be in danger from the radiation from a typical recreational boat radar like a Furuno would be to hold one's head against the radome of an operating radome for a week.

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Maybe you're onto something here. "Oh no honey, it's fine, just lay back down and keep sunbathing... Just keeeeeeep sunbathing..."

Northern Spy said:

Maybe you're onto something here. "Oh no honey, it's fine, just lay back down and keep sunbathing... Just keeeeeeep sunbathing..."

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Hey in Florida they slather on the baby oil and line the beach recliner in tin foil...well done by 1400.

....should work with microwaves too if the tin foil is crinkled correctly...

Safe? Sure it's safe, no worse than sunbathing!

Just climb up there any time, and hey, the view is great!

LarryM said:

Safe? Sure it's safe, no worse than sunbathing!

Just climb up there any time, and hey, the view is great!

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I bet you could cook a turkey at 100 paces with some of that equipment.

I tried to look for the safety zone just north of the Aleutian Island Shemya where they had I think...a Cobra Dane RADAR.


The safety zone extended quite a ways off the coast...but I don't see it on the nautical charts anymore.


Maybe decommissioned...but that baby was supposed to be a butt kicker of a RADAR.....supposed to see stuff lifting off the ground in Russia.

Larry,
I think you are mostly right. Since radar frequencies are well below the "ionizing" frequency the major effect is heating. (ionizing radiation will destroy cells, i.e. ultraviolet) In that case the average power is what is important. However, some argue that the brain and nervous system as well as the eyes operate on electrical impulses. The higher peak power can possibly induce voltages that would interfere with the normal functions of these systems. Even after 70 years of radar use this is still an open issue. I personally would not stand in front of a pulse radar but would be much less concerned with a CW/FM radar which has very low peak power.
Paul