Radar
Moderators: CaptPatrick, mike ohlstein, Bruce
Radar
I see some radar domes mounted on the front on the fly bridge on B31's. With todays new radars, is this ok? Seems like the beam would shoot right through who ever is driving the boat on the bridge. I have a Bimini on my bridge. I would prefer no radar arch. Is the radar mounted on the front ok? what is every ones thoughts?
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trace elements
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Re: Radar
I was reading about this yesterday. Per Garmin, you should be a minimum of 4-16" away from the dome depending on the model. Otherwise, they state it is safe.
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Tony Meola
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Re: Radar
They might say it is safe, but I probably would not do it. You really are pretty close to that dome when it is mounted that low.
1975 FBC BERG1467-315
Re: Radar
Here is an article on the subject from Gamefisherman web site:
MARINE RADAR: HEALTH MYTHS DEBUNKED
People hear the word “radiation” and it freaks them out – and rightfully so. I can’t tell you how many times I’ve heard a captain, mate, or owner talk about staying away from a working radar with fear of turning brains into “scrambled eggs”, and have even heard people say they get a headache if they get too close.
We did some research to find an answer to the ever-debated question once and for all: is marine radar hazardous to your health?
Short answer: According to the World Health Organization (WHO), not really – it’s all in your head (pun intended). To produce health defects, exposure would be 1000 W/m2 or more, and marine radars on pleasure boats don’t reach more than 10 W/m2. You would also have to stand directly in front of the very narrow beam for a significant amount of time, and that’s impossible while it’s spinning.
“People hear the word radiation and it scares them because we’re sending out a little blip of energy and it’s energy that’s coming home,” says Eric Kunz, senior product manager for Furuno USA. “But it’s not the same kind of energy. Nuclear radiation is associated with change in the biological structure of a cell.”
Long answer: Absorption of radio frequency (RF) fields in tissues is measured by Specific Absorption Rate (SAR). An SAR of at least 4 W/kg is needed to produce known adverse health effects in people exposed to RF fields in this frequency range.
RF fields above 10 GHz are absorbed at the skin surface, with very little of the energy penetrating into the underlying tissues. The basic dosimetric quantity for RF fields above 10 GHz is the intensity of the field measured as power density in watts per square metre (W/m2). Exposure to RF fields above 10 GHz at power densities over 1000 W/m2 are known to produce adverse health effects, such as eye cataracts and skin burns.
Peak powers of marine radars can reach up to 30 kW, with average powers ranging from 1 to 25 W. Under normal operating conditions, with the antenna rotating, the average power density of the higher power systems within a metre of the antenna is usually less than 10 W/m2. In accessible areas on most watercraft, these levels would fall to a few percent of present public RF exposure standards.
Also keep in mind, radars send electromagnetic waves in pulses (not continuously), and they are directional and very narrow like the beam of a spot light (RF levels fall off rapidly outside of that main beam), meaning this makes the average power emitted much lower than the peak pulse power.
“Uninformed boaters often equate a marine radar with a microwave oven, and their body as a frozen bean burrito,” says Jim McGowan, marketing manager for the Americas for Raymarine. “It’s true that both systems use microwave energy, and generate that energy using a device called a magnetron. For comparison purposes, most microwave ovens range in power output from 0.8 kilowatt (800 watts) to 1 kilowatt. The burrito analogy doesn’t hold up though because of a fundamental difference in the way a microwave oven works versus a marine radar. In order to heat your burrito, from the inside out no less, a microwave uses continuous-wave microwave energy. That means its magnetron is on and hammering away with 1 kilowatt of energy for its entire cook cycle. The microwave energy actually excites the molecules in the food, causing them to move faster and generate heat. This is what warms the food. The longer the exposure to the continuous-wave energy, the faster the molecules go and the hotter it gets.” That sounds unpleasant, to be cooked from the inside. But it doesn’t happen to boaters.
“The magnetron marine radar works differently in that it uses pulsed microwave energy,” McGowan says. “That is, the radar scanner actually turns itself on and off thousands of times a second. It does this so it can send a pulse, then listen for its faint echo returning. Depending on the range selected, the radar’s pulse could be short, long, or somewhere in between. But, even with a long pulse, the radar is only actually radiating for a few thousandths of a second at a time. Because of that constant on/off effect, the marine radar never generates power long enough to get the molecules moving in whatever objects are in the path of its beam. No heat means no cooking, burritos or otherwise.”
Consensus: You’re more likely to be hit by a spinning radar than fried by one.
Jokes aside, everyone has their own beliefs and superstitions, so use radar at your own risk and do your own research on the specific model you run, but please don’t be “that guy” still spinning at the dock.
For updated and more in-depth information about how marine radar could effect your health, visit the World Health Organization’s website here: https://www.who.int/news-room/q-a-detai ... the%20body.
Thank you to Jason Y. Wood of Power and Motoryacht for the quotes above.
MARINE RADAR: HEALTH MYTHS DEBUNKED
People hear the word “radiation” and it freaks them out – and rightfully so. I can’t tell you how many times I’ve heard a captain, mate, or owner talk about staying away from a working radar with fear of turning brains into “scrambled eggs”, and have even heard people say they get a headache if they get too close.
We did some research to find an answer to the ever-debated question once and for all: is marine radar hazardous to your health?
Short answer: According to the World Health Organization (WHO), not really – it’s all in your head (pun intended). To produce health defects, exposure would be 1000 W/m2 or more, and marine radars on pleasure boats don’t reach more than 10 W/m2. You would also have to stand directly in front of the very narrow beam for a significant amount of time, and that’s impossible while it’s spinning.
“People hear the word radiation and it scares them because we’re sending out a little blip of energy and it’s energy that’s coming home,” says Eric Kunz, senior product manager for Furuno USA. “But it’s not the same kind of energy. Nuclear radiation is associated with change in the biological structure of a cell.”
Long answer: Absorption of radio frequency (RF) fields in tissues is measured by Specific Absorption Rate (SAR). An SAR of at least 4 W/kg is needed to produce known adverse health effects in people exposed to RF fields in this frequency range.
RF fields above 10 GHz are absorbed at the skin surface, with very little of the energy penetrating into the underlying tissues. The basic dosimetric quantity for RF fields above 10 GHz is the intensity of the field measured as power density in watts per square metre (W/m2). Exposure to RF fields above 10 GHz at power densities over 1000 W/m2 are known to produce adverse health effects, such as eye cataracts and skin burns.
Peak powers of marine radars can reach up to 30 kW, with average powers ranging from 1 to 25 W. Under normal operating conditions, with the antenna rotating, the average power density of the higher power systems within a metre of the antenna is usually less than 10 W/m2. In accessible areas on most watercraft, these levels would fall to a few percent of present public RF exposure standards.
Also keep in mind, radars send electromagnetic waves in pulses (not continuously), and they are directional and very narrow like the beam of a spot light (RF levels fall off rapidly outside of that main beam), meaning this makes the average power emitted much lower than the peak pulse power.
“Uninformed boaters often equate a marine radar with a microwave oven, and their body as a frozen bean burrito,” says Jim McGowan, marketing manager for the Americas for Raymarine. “It’s true that both systems use microwave energy, and generate that energy using a device called a magnetron. For comparison purposes, most microwave ovens range in power output from 0.8 kilowatt (800 watts) to 1 kilowatt. The burrito analogy doesn’t hold up though because of a fundamental difference in the way a microwave oven works versus a marine radar. In order to heat your burrito, from the inside out no less, a microwave uses continuous-wave microwave energy. That means its magnetron is on and hammering away with 1 kilowatt of energy for its entire cook cycle. The microwave energy actually excites the molecules in the food, causing them to move faster and generate heat. This is what warms the food. The longer the exposure to the continuous-wave energy, the faster the molecules go and the hotter it gets.” That sounds unpleasant, to be cooked from the inside. But it doesn’t happen to boaters.
“The magnetron marine radar works differently in that it uses pulsed microwave energy,” McGowan says. “That is, the radar scanner actually turns itself on and off thousands of times a second. It does this so it can send a pulse, then listen for its faint echo returning. Depending on the range selected, the radar’s pulse could be short, long, or somewhere in between. But, even with a long pulse, the radar is only actually radiating for a few thousandths of a second at a time. Because of that constant on/off effect, the marine radar never generates power long enough to get the molecules moving in whatever objects are in the path of its beam. No heat means no cooking, burritos or otherwise.”
Consensus: You’re more likely to be hit by a spinning radar than fried by one.
Jokes aside, everyone has their own beliefs and superstitions, so use radar at your own risk and do your own research on the specific model you run, but please don’t be “that guy” still spinning at the dock.
For updated and more in-depth information about how marine radar could effect your health, visit the World Health Organization’s website here: https://www.who.int/news-room/q-a-detai ... the%20body.
Thank you to Jason Y. Wood of Power and Motoryacht for the quotes above.
Re: Radar
My friend Wolfgang....eh, I'll skip the story and leave it as a brilliant electronic technician whose communication antennas dot the world, a person called in to repair radars on ships, the SI Ferry blah blah blah... told me on more than one occasion, don't be in front of an array.
A summary from WHO below sounds to be inconclusive in my opinion. Yes, you're not going to be immediately cooked...but maybe more of sous vide slow cook. I would not worry about a quick occasional ride, but to sit at the helm for hours taking a cruise or trolling with an array shooting at my_______ (fill in the blank), I'd err on the side of caution placing the array a bit higher or lower.
https://www.who.int/news-room/questions ... tion-radar
In Summary
RF fields cause molecules in tissue to vibrate and generate heat. Heating effects could be expected if time is spent directly in front of some radar antennas, but are not possible at the environmental levels of RF fields emanating from radar systems.
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.
A summary from WHO below sounds to be inconclusive in my opinion. Yes, you're not going to be immediately cooked...but maybe more of sous vide slow cook. I would not worry about a quick occasional ride, but to sit at the helm for hours taking a cruise or trolling with an array shooting at my_______ (fill in the blank), I'd err on the side of caution placing the array a bit higher or lower.
https://www.who.int/news-room/questions ... tion-radar
In Summary
RF fields cause molecules in tissue to vibrate and generate heat. Heating effects could be expected if time is spent directly in front of some radar antennas, but are not possible at the environmental levels of RF fields emanating from radar systems.
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.
Re: Radar
I don't support the article one way or the other. Just one info source.
But having my hands burned by RF at one time when someone keyed up when putting up the antenna with a linear amp attached, we are being bombarded by rf and microwaves everyday of which there is nothing we can do.
There's never a bad reason for being extra careful though or erroring on the side of caution.
But having my hands burned by RF at one time when someone keyed up when putting up the antenna with a linear amp attached, we are being bombarded by rf and microwaves everyday of which there is nothing we can do.
There's never a bad reason for being extra careful though or erroring on the side of caution.
Re: Radar
Yes, we are bombarded with RF and microwaves evereyday, but from a distance...aside from the phone in my pocket, which also gets placed to my ear on calls.
I'd think the closer to the point the signal or wave emanates the more power it has...but I'm only guessing.
I think we are on the same page, I'm not going to line myself in tin foil or worry about that I cannot control, but if I have a choice of placing my radar array in front of my helm seat or placing a bit higher than my body, to be safer than sorry, I'll place it higher...even if a bit less snazzy. That said, mine sits on a short pedestal on my tower floor, just below the helm, around shin level. However, when used 99% of the time I'm at the lower helm where the radar display is...the other 1% I don't worry about.
I'd think the closer to the point the signal or wave emanates the more power it has...but I'm only guessing.
I think we are on the same page, I'm not going to line myself in tin foil or worry about that I cannot control, but if I have a choice of placing my radar array in front of my helm seat or placing a bit higher than my body, to be safer than sorry, I'll place it higher...even if a bit less snazzy. That said, mine sits on a short pedestal on my tower floor, just below the helm, around shin level. However, when used 99% of the time I'm at the lower helm where the radar display is...the other 1% I don't worry about.
Re: Radar
We have come a long way to just have this discussion. When I was a child my parents took me to a shoe store which was showing off its new foot sizing machine. The salesman turned it on and had me place my foot in the slot. Looking on the screen we could see the bones in my foot. It was an early primitive X ray machine! I'm glad they weren't sizing me for pants or a hat.
Everything I read says the new radar technology is safe but I still err on the side of caution wherever practical. In the next 10-20 years we will learn so much more, some of which will leave us scratching our heads "what were we thinking?".
Everything I read says the new radar technology is safe but I still err on the side of caution wherever practical. In the next 10-20 years we will learn so much more, some of which will leave us scratching our heads "what were we thinking?".
Doug Pratt
Bertram 31 Amberjack
FBC hull #315-820
Bertram 31 Amberjack
FBC hull #315-820
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Tony Meola
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Re: Radar
Heck they are still arguing over the effects of cell phones on us, or sitting on top of a bank of batteries in an electric car.
I would err on the side of safety and raise it up.
I would err on the side of safety and raise it up.
1975 FBC BERG1467-315
Re: Radar
I would kind of agree with the article but for a slightly different reason, the radome is spinning 360 degrees, if sitting directly behind, you are only getting the beam 60-90 degrees so 1/4 or less of the time. The other part is that the beam is fairly compact the closer you are to the radar.
https://www.thehulltruth.com/attachment ... 1313671829
personally I wouldn't want the exposure facing my head or privates, if it were at shin level I wouldn't see an issue
https://www.thehulltruth.com/attachment ... 1313671829
personally I wouldn't want the exposure facing my head or privates, if it were at shin level I wouldn't see an issue
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Tony Meola
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- Location: Hillsdale, New Jersey
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PeterPalmieri
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- Location: Babylon, NY
Re: Radar
If you are primarily a fisherman and are running radar all the time I would want it on a top. If you are a cruiser with a Bimini top or no top and you are going to only occasionally put on the radar in the fog or for a quick ride home at night I wouldn’t have a problem mounting it on the front of the bridge. That’s just my opinion.
1969 31 Bertram FBC "East Wind" hull #315939
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PeterPalmieri
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Re: Radar
I’m mounting mine overhead as I plan on running it all the time. But if it’s really just a nav tool at night or in the fog, kind of an emergency thing I’m guessing you won’t have kids up there.
That being said kids can’t even drink from a garden hose anymore so I’m guessing a lead radiation suit is necessary.
That being said kids can’t even drink from a garden hose anymore so I’m guessing a lead radiation suit is necessary.
1969 31 Bertram FBC "East Wind" hull #315939
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Marshall Mahoney
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Re: Radar
I was running down river in my buddies center console in a low hanging fog. If I stood on the gunnel of the boat I could see pretty good over the fog. It took me 30 minutes to realize that I was eye to eye with his open array radar. I got off of the gunnel and was throwing up over the side 20 min later. Psychosomatic? Probably. But I have never been seasick in my life (not counting the Grand Isle Tarpon Rodeo of course). I blame the radar.