Low radar arch

[MikeJ42]

My radar is the exact same height as my head on the flybridge. I see that lots of modern boats seem to have low radar arches. Is this to give the impression of sleekness?
I feel that the only time I can use my radar is when sitting downstairs…and if its foggy or dark (when I really need it) I'll want to be upstairs. I know I am 'supposed' to be using it all the time, but its never turned on.
Even the Scanstruts pedestals only raise it a matter of inches. Surely its not a good idea to sit 10ft in front of it? Am I worrying unduly?

 

[omega2]

They do say the rays will fry your brain, I know that commercial ships shut down and post warnings at the bottom of the mast ladders. Maybe a lead helmet will will protect you?? Use the radar as often as you can even in in 20/20 vis then you wuill know what you are looking at when you need it in earnest.

 

[Wiggo]

In brief, yes, you can ignore the thing. At 10', the energy you absorb from it is negligible. I seem to recall working out many years ago that if you glued an egg to the front of a 4kW scanner, it would be soft boiled in less than 35 years.

 

[benjenbav]

Apart from any health risk, surely these sleek low-mounted designs spend most of their time looking at the f/b helm rather than anything outside the boat?

 

[Wiggo]

The helm is pretty radar transparent (as is most of the boat, hence the need for radar reflectors), and far too close to affect the radar picture in any event. The biggest issue with installation is ensuring that the radar scanner is aligned to allow for the boat's running trim, otherwise it spends most of its time looking at the sky.

 

[timbartlett]

Am I worrying unduly?

You are certainly safer if you drive from downstairs -- but mainly because it gets you out of the hazardous radiation from the sun.

Radar only transmits for about 0.1% of the time, and you are in the "beam" for about one hundredth of the time. You receive so little energy that it will not cook you in a month of Sundays. You are at more danger from your mobile phone -- and a lot more danger from the Sun. Plus there's the fact that some of the energy from the sun is at frequencies high enough to (potentially) cause mutations within the cells of your body (cancer) which radar isn't.

You are worrying unduly.

 

[MikeJ42]

You are certainly safer if you drive from downstairs -- but mainly because it gets you out of the hazardous radiation from the sun.

Radar only transmits for about 0.1% of the time, and you are in the "beam" for about one hundredth of the time. You receive so little energy that it will not cook you in a month of Sundays. You are at more danger from your mobile phone -- and a lot more danger from the Sun. Plus there's the fact that some of the energy from the sun is at frequencies high enough to (potentially) cause mutations within the cells of your body (cancer) which radar isn't.

You are worrying unduly.

Thank you (I think), but I now have many more questions...

 

[PaulGooch]

I'd recommend all of you with fly bridges wear full radiation suits

 

[kid's inheritance]

and a lot more danger from the Sun. .

Surely only if you are a professional footballer who's bonked your teammates wife?

 

[omega2]

I'd recommend all of you with fly bridges wear full radiation suits

but if from Essex carry on as are!!

 

[Jeepster]

You are certainly safer if you drive from downstairs -- but mainly because it gets you out of the hazardous radiation from the sun.

Radar only transmits for about 0.1% of the time, and you are in the "beam" for about one hundredth of the time. You receive so little energy that it will not cook you in a month of Sundays. You are at more danger from your mobile phone -- and a lot more danger from the Sun. Plus there's the fact that some of the energy from the sun is at frequencies high enough to (potentially) cause mutations within the cells of your body (cancer) which radar isn't.

You are worrying unduly.

No he's not!!! You obviously know absolutely nothing about high power microwave RF and its effect on the human body...He is completely right to very worried about having his head in line with the Radar antenna.
This is a quote from a warning given at the start of a Furuno radar manual:
"The radar scanner emits electromagnetic radio frequency (RF) energy which can be harmful, particularly to your eyes. Never look directly into the scanner aperture from a close distance while the radar is in operation or expose yourself to the transmitting scanner at a close distance.
Distances at which RF radiation levels of 100 and 10 W/m2 exist are given in the table below. Note: If the scanner unit is installed at a close distance in front of the wheel house, your administration may require halt of transmission within a certain sector of scanner revolution. This is possible—Ask your FURUNO representative or dealer to provide this feature."

It then shows a table showing minimum safe distances to be away from the antenna...For a 4kw radar you should be no less than 1.2m away...Thats 4 foot away and that rises to 1.7m, almost 6 feet away, for a 6kw radar.
It will cook his eyes before his head but it WILL cook him if he gets close enough!

 

[timbartlett]

No he's not!!! You obviously know absolutely nothing about high power microwave RF and its effect on the human body...He is completely right to very worried about having his head in line with the Radar antenna.

Please do not be gratuitously rude. As it happens, I have studied this particular topic in some depth. It appears that you have not. If you want to get picky about it, I accept that marine radar is not intrinsically safe, but "not intrinsically safe" is not the same as "dangerous".

Here's a slightly edited extract from an article I wrote for an american magazine a couple of years ago:-

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has set exactly the same limits as the FCC, but has added some practical guidelines expressed in terms of power density. According to ICNIRP, the FCC’s “general public” limit corresponds to a power density of 10W/m2, while its “occupational” limit equates to 50W/m2.
Counting the pulse
Pulsed radar transmits pulses. Each pulse lasts for less than a millionth of a second, and there are only a few hundred of them per second, so a typical yacht radar is transmitting for only about 0.05% of the time, reducing the average power output of a 2kW radar to a much more docile-sounding 1W.
That power, though, is concentrated into a beam – but not the well-defined fan-shaped beam of navigation text books! It has blurred edges and stray waves escaping at all sorts of odd angles. And it’s not really fan-shaped, either: for a few inches, close to the antenna, the sides of the beam are almost parallel to each other.
This means that at the surface of the radome, the beam of a typical 2kW radar covers an area of about 0.06m2. The 1W average output of a 2kW radar, spread over an area of 0.06m2, works out at a power density of about 22W/m2.
But the beam is constantly rotating. So even if you are right next to the radome, you can never be in the beam for more than about 30% of the time.
So even if you are actually touching the radome of a 2kW radar, you are subjecting yourself to an average power density of about 7 Watts per square metre – well on the right side of the ICNIRP’s general public limit.
Doing the same calculation for a 4kW radar with a 24inch scanner gives a power density of 10W/m2.

You don't specify which particular manual you plucked your figures from, but I concede that power densities in the order of 10w/ms are possible within a metre or so of a medium-power radar. But only if you take the worst case scenario: transmitting on long pulse, with the highest possible PRF, with the scanner stationary and with the subject located right in the centre of the main lobe. Such a combination of circumstances is highly unlikely. The chances of maintaining it for long enough to cause any damage is virtually zero.

 

[Jeepster]

Please do not be gratuitously rude. As it happens, I have studied this particular topic in some depth. It appears that you have not. If you want to get picky about it, I accept that marine radar is not intrinsically safe, but "not intrinsically safe" is not the same as "dangerous".

Here's a slightly edited extract from an article I wrote for an american magazine a couple of years ago:-


You don't specify which particular manual you plucked your figures from, but I concede that power densities in the order of 10w/ms are possible within a metre or so of a medium-power radar. But only if you take the worst case scenario: transmitting on long pulse, with the highest possible PRF, with the scanner stationary and with the subject located right in the centre of the main lobe. Such a combination of circumstances is highly unlikely. The chances of maintaining it for long enough to cause any damage is virtually zero.

Apollogies if I came over as rude...Just could'nt understand why someone could be so completely dismissive of the risks...And yes, there are risks.
However, if you noticed at the end of that Furuno radar manual warning it states that it is possible to turn off the beam over the part of its sweep corresponding to the position of the operator and that with some authorities it is a legal requirement...As long as he did'nt stray from his seat he'd be ok, but when he gets up to go down from the flybridge he might pass the beam again but of course for a much shorter period than before when the beam was 360 degrees. I dont know if Radar systems by other manufacturers can be made to do this but he should certainly look into it.

 

[paultallett]

My vote still goes to the lead helmit...... I can just see that catching on with the fashionista amoungts us!!

On a much more serious note, why do alot of FB boats have 'upstairs' BBQ's when it's very clear that to cook your burgers it would be much easier just to pop the radar on and put the plate in front of the scanner??

I'll get my coat................

 

[Wiggo]

However, if you noticed at the end of that Furuno radar manual warning it states that it is possible to turn off the beam over the part of its sweep corresponding to the position of the operator

Errm, wouldn't that leave a rather inconvenient radar blind spot dead ahead of the boat? Not the most useful of features IMO...

Surely a simple tinfoil helmet connected to ground with a suitable earthing strap would be easier (and lighter) than a lead helmet? It's only electromagnetic energy, not ionising radiation we're trying to stop here, unless you have a radar that operates in the X-Ray band.

 

[timbartlett]

It's only electromagnetic energy, not ionising radiation we're trying to stop here, unless you have a radar that operates in the X-Ray band.

Don't confuse people with all that scientific jargon. It's radiation innit? And of course everybody knows that radiation makes you swell up and turn green.
And still these lackadaisical Health and Safety chaps allow radar manufacturers to go on making these dangerous things and boatbuilders to go on fitting them.
Despite all the well-publicised accounts of motorboaters turning into giant lizards.

 

[Wiggo]

True, true. No point in letting inconvenient facts get in the way of a story, eh? Giant lounge lizards, I guess. Fits with the whole mobo/drug dealer/pimp lifestyle...

 

[oGaryo]

nuts!!! protect them that is if my experiences working in proximity of the raydomes stuck on the front of fighter aircraft is anything to go by.. want kids? then don't walk in front of the things.

Suspect those systems were a tad more powerful though but I guess the advice still applies.. never never never hang upside down from your radar arch whilst underway with the rader on