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Guest
Guest
I notice many flybridge boats have their scanner directly behind the crew. Are there any safety implications here?
Geoff
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Geoff
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mainshiptom
Well-Known Member
You will also notice that it is only used when the boat is being driven from down stairs postion ! No people sholud be up on deck when in use ! A skipper responsibility !
I have a rader on my boat , there is no screen above and I can only use when down below, some boats would also have a switch on deck so when people are up on deck the rader can not be switched on, quite simple to install.
Tom
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I have a rader on my boat , there is no screen above and I can only use when down below, some boats would also have a switch on deck so when people are up on deck the rader can not be switched on, quite simple to install.
Tom
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Wiggo
Well-Known Member
Yes, positioning the radar directly in front of the crew restricts visibility and IS a safety hazard.
Seriously, look at the power consumption of a radar set. Typically 50W for a 2kW scanner (that's 50W continuous). So it's putting out 6% of the power of your microwave oven. And it's rotating. The beam width is about 6 degrees, or 1/60 of a circle, so if you sit six feet in front of it, it's about the width of your head. So in each rotation, you spend only 1/60 of the time exposed to the beam.
That means you are exposed to less than 1W of emitted microwave radiation. The power falls off with the square of the distance, and your microwave cooks food from 6" away, or 0.5 feet. You are 6 feet away, or 12 times as far, so the received power at your head falls by a factor of 144.
So, it's the equivalent of trying to cook with a 5.8mW microwave. I'll take my chances...
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Seriously, look at the power consumption of a radar set. Typically 50W for a 2kW scanner (that's 50W continuous). So it's putting out 6% of the power of your microwave oven. And it's rotating. The beam width is about 6 degrees, or 1/60 of a circle, so if you sit six feet in front of it, it's about the width of your head. So in each rotation, you spend only 1/60 of the time exposed to the beam.
That means you are exposed to less than 1W of emitted microwave radiation. The power falls off with the square of the distance, and your microwave cooks food from 6" away, or 0.5 feet. You are 6 feet away, or 12 times as far, so the received power at your head falls by a factor of 144.
So, it's the equivalent of trying to cook with a 5.8mW microwave. I'll take my chances...
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david_bagshaw
Well-Known Member
Also , you recieve more radiation from a mobile phone, when it is glued to the ear !!
<hr width=100% size=1>David
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jimi
Well-Known Member
Suppose it could be handy on a chilly day as a sort of patio heater for the helm?
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KevB
Well-Known Member
Don't the COL regs say something about all nevigation/collision equipment fitted to a boat should be used at all time when underway?? Well if that's the case then flybridge boats should only be driven from downstairs.
I think what you will find also is that even if the dome is above head height the beam is angled down so as to focus on the horizon when the boat is on the plain?
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I think what you will find also is that even if the dome is above head height the beam is angled down so as to focus on the horizon when the boat is on the plain?
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G
Guest
Guest
Mobile phones clearly cause brain interference, witness the way users walk in random patterns and shout while using them.
Geoff
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Geoff
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tcm
...
at last a point of agreement, kevb. I think they do say "all available" or whatever, which means if you have radar it shd be ON.
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Moose
Well-Known Member
What about a 10kw 48" Scanner?
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L' Moose
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L' Moose
BarryH
Well-Known Member
Your boasting again. Just 'cos you've got 35mm nuts
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BrendanS
Well-Known Member
What about a 10kw 48\" Scanner?
Your antlers get toasted !!!!! /forums/images/icons/laugh.gif
Wasn't there a thread on this quite some while back, and it was pointed out that if in the litigious US, radars can be mounted just above peeps heads, there can't be too much harm. I think (probably woncky memory, and can't be bothered to go search) that Kim was gonna get the magazines to look into it.
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Your antlers get toasted !!!!! /forums/images/icons/laugh.gif
Wasn't there a thread on this quite some while back, and it was pointed out that if in the litigious US, radars can be mounted just above peeps heads, there can't be too much harm. I think (probably woncky memory, and can't be bothered to go search) that Kim was gonna get the magazines to look into it.
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Wiggo
Well-Known Member
Re: 10kW 48\" array
5 times the output and a slightly narrower beam width, so more concentrated power, so let's say the equivalent of a 35mW microwave. Impale an average jacket spud on an antler, and it should cook in approximately 100 days.
Actually, the 50W consumption on my 2kW set includes the power to drive the display and its backlight as well, so perhaps a round 4 months for that spud.
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5 times the output and a slightly narrower beam width, so more concentrated power, so let's say the equivalent of a 35mW microwave. Impale an average jacket spud on an antler, and it should cook in approximately 100 days.
Actually, the 50W consumption on my 2kW set includes the power to drive the display and its backlight as well, so perhaps a round 4 months for that spud.
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jimi
Well-Known Member
RYA RC98
Radar transmits very short pulses of microwave energy which could cook parts of the human body exposed to it, especially the eyes and gonads. In small craft radars, however, the power is so low and the pulses so short that there is no significant hazard to a healthy adult. There is a possible risk to anyone using a cardiac pacemaker, which may be affected by the pulses.
To be on the safe side:-
Avoid lingering in the radar beam or looking straight at the scanner while the radar is transmitting
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Radar transmits very short pulses of microwave energy which could cook parts of the human body exposed to it, especially the eyes and gonads. In small craft radars, however, the power is so low and the pulses so short that there is no significant hazard to a healthy adult. There is a possible risk to anyone using a cardiac pacemaker, which may be affected by the pulses.
To be on the safe side:-
Avoid lingering in the radar beam or looking straight at the scanner while the radar is transmitting
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Observer
Well-Known Member
<blockquote><font size=1>In reply to:</font><hr>
Don't the COL regs say something about all nevigation/collision equipment fitted to a boat should be used at all time when underway
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Colregs actually says "by all available means appropriate in the prevailing circumstances".
So, for a typical pleasure boat, not necessary to use radar in daylight and good visibility. I would say always necessary in fog and probably also at night.
But then there is also the issue of the extent to which monitoring a radar screen can detract from effective visual lookout. It is quite hard, in pilotage waters, where there is a primary need to see and avoid unlit navigation marks (in addition to other traffic and lit buoys), for one person to keep an effective radar watch as well as visual lookout. So effective use of radar requires a second person who is fully competent to monitor the radar or to take the helm. On night passages, I usually concentrate on visual lookout. I think I would always have radar switched on but how much I use it (at risk of reducing night vision or distracting from visual lookout) is another matter.
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Don't the COL regs say something about all nevigation/collision equipment fitted to a boat should be used at all time when underway
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Colregs actually says "by all available means appropriate in the prevailing circumstances".
So, for a typical pleasure boat, not necessary to use radar in daylight and good visibility. I would say always necessary in fog and probably also at night.
But then there is also the issue of the extent to which monitoring a radar screen can detract from effective visual lookout. It is quite hard, in pilotage waters, where there is a primary need to see and avoid unlit navigation marks (in addition to other traffic and lit buoys), for one person to keep an effective radar watch as well as visual lookout. So effective use of radar requires a second person who is fully competent to monitor the radar or to take the helm. On night passages, I usually concentrate on visual lookout. I think I would always have radar switched on but how much I use it (at risk of reducing night vision or distracting from visual lookout) is another matter.
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Wiggo
Well-Known Member
Re: Lead codpiece
I never go to sea without one.
However. A radar may fire 1200 pulses per second, each one lasting 1.5 microsecs. In that 1.5 microsec pulse, the radar will emit 0.003 Joules of energy. It rotates at 24 rpm, so each rev takes 2.5 seconds, or 480 pulses per revolution. At 6 feet distance, your head presents a target aproximately 6 degrees of arc wide, and the set fires 4 pulses every 3 degrees, so you will be hit by eight pulses.
Actually, it is higher than that, since each pulse is spread over 6 degrees, so you would actually receive 8 pulses per rev of the scanner, or 192 pulses per minute. Your dosage is therefore 192 x 0.003 = 0.576 Joules per minute, or 0.0096 Watts.
You can considerably increase your dosage by running round the flybridge in circles, ensuring that you stay in front of the beam. This is clearly far easier with an open array than with a radome scanner, although you could modify the top of a radome to allow you to mount a small 'telltale', perhaps made from a wire coathanger and a small piece of plastic.
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I never go to sea without one.
However. A radar may fire 1200 pulses per second, each one lasting 1.5 microsecs. In that 1.5 microsec pulse, the radar will emit 0.003 Joules of energy. It rotates at 24 rpm, so each rev takes 2.5 seconds, or 480 pulses per revolution. At 6 feet distance, your head presents a target aproximately 6 degrees of arc wide, and the set fires 4 pulses every 3 degrees, so you will be hit by eight pulses.
Actually, it is higher than that, since each pulse is spread over 6 degrees, so you would actually receive 8 pulses per rev of the scanner, or 192 pulses per minute. Your dosage is therefore 192 x 0.003 = 0.576 Joules per minute, or 0.0096 Watts.
You can considerably increase your dosage by running round the flybridge in circles, ensuring that you stay in front of the beam. This is clearly far easier with an open array than with a radome scanner, although you could modify the top of a radome to allow you to mount a small 'telltale', perhaps made from a wire coathanger and a small piece of plastic.
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Wiggo
Well-Known Member
I try and keep it on at all times, since in broad daylight it strikes me as good practice to 'spot' radar targets by eye. At night, I find that the radar shows the relative positions of buoys and other vessels, when the Mk I eyeball does not give any depth perception - spot the light by eye, cross check on the radar to identify how far off it is, cross check the plotter to determine if it is a buoy or a boat. If the latter, then you have something that needs special attention.
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Observer
Well-Known Member
Yes agreed. Depth perception is the main problem at night and radar will facilitate differentiation as you described.
Use in daylight with good vis. would vary according to traffic I suggest. If there is a large number of targets on the screen (typical Solent weekend) there is a risk of distraction. If some targets/traffic but not so as to require frequent course changes, good opportunity to practise and improve radar lookout skills.
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Use in daylight with good vis. would vary according to traffic I suggest. If there is a large number of targets on the screen (typical Solent weekend) there is a risk of distraction. If some targets/traffic but not so as to require frequent course changes, good opportunity to practise and improve radar lookout skills.
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CliveWright
New Member
Not again .... I see that KevB is beating the drum against those of us with flybridge boats .... come on Kev ... you know you want one!
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