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Old 19 October 2004, 12:26   #31
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A frame height

Thank you Brian for your input. The problem we would have in going higher is really a proportional one and that of equal weight distrubution, however I have today discussed with our electronics guys in Chatham and this is for sure a mixed debate. Their offcial viewpoint is Do not stand in front of the transmission from the radome for a indefinate period of time. Given the type of craft I have and its uses I will helm this from the seating posistion as opposed to standing up therefore absolutely plenty of height even at the helm in the standing up I am below the Radome.

Unlike the smaller Ribs i intend to "drive " in the seated posistion 90% of the time especially for extended voyages. The need to stand is not the same as for example in "platypus " my old 6.3 mt demo craft. I guess there will always be those who advocate and those who do not. At the end of the day its down to common sense.I think our central A frame system is the best compromise i have seen on a open 9mt Rib though.

David B
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Old 19 October 2004, 12:58   #32
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Quote:
Originally Posted by Brian
David B
Any chance of getting a slightly higher A-frame. It still looks a bit low to me if the brain fryers are to be believed.

Everyone else as well as David B.
I still maintain there isnt a problem. No expert has come on here to tell us that we are going to be death-rayed. The HSE police are quiet on the subject. Nobody has posted any actual anecdotal evidence of damage to humanoids.

I reckon we are OK.
Obviously the risk IS small but not to be ignored all together!!!

As to evidence there is plenty if you know where to look and sort out the actual science from the hype from the luddites!!!

From the HSE

"Sensible precautions

If radar equipment is to be worked on under power in port, sensible precautions would include ensuring that:

no one is close to the scanner, ie within a few metres,
the scanner is rotating or if the work requires the scanner to be stationary, that it is directed to unoccupied areas, eg out to sea,
no one looks directly into the emission side of a slotted wave guide (open box type) scanner,
no one is able to position themselves between the output horn of the transmitter and the reflector of larger scanners,
the risk of being hit by a rotating scanner is not overlooked if work close to the installation is necessary. "


"Microwaves (RF energy at radar frequencies) can be hazardous if the intensity is sufficiently high. Microwaves are absorbed by the water in living tissue and their energy is converted to heat that may easily damage some organs, particularly the eyes, which may develop cataracts. For safety, always avoid looking directly into a scanner whether the radar is transmitting or not. It is well known that microwaves will interfere with cardiac pacemakers and it is common place to see the warning signs in public areas where microwave ovens are in use.

It has also been shown that long-term exposure to low levels of microwave radiation can induce a variety of physiological effects in small laboratory animals. The importance of these effects and their relevance to humans are not yet fully understood. Again for safety reasons, you should avoid long-term exposure and radar units should be operated only when needed for navigation or safety. When the radar is not needed, it should either be in standby mode (not transmitting) or turned off.

Obviously, the radiation levels associated with marine radar units will vary according to the particular make and model. A radar unit of three kilowatts up to approximately 0.5 watts per centimeter squared, operating in the X-band at 3-1/2 feet from and at the same height as the scanner, can be encountered. OSHA has determined that the recommended maximum safe level of exposure to microwaves is 0.2 milliwatts per centimeter squared. The average intensity can be as high as 0.8 (milliwatts per centimeter squared) when the scanner is stationary. At a distance of 7 to 10 feet from the scanner, the average intensity drops to safe levels (i.e. below 0.2 mW/cm2).

At points above or below the scanner's horizontal plane, the radiation level is lower than that measured at a corresponding point on that plane. However, it must be noted that the average radar has a rather large vertical beam width (20 to 25 degrees) and microwave radiation is beamed about 10 to 12 degrees above and below the horizontal plane. At 5 feet from the scanner and 1-1/2 foot below the scanner, the average intensity can still be in excess of the OSHA safety limit."
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Old 20 October 2004, 06:29   #33
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Hse

Hello Mr Cod Prawn ,

What a post........you must have a degree in Microwave energy
Either way thank you for your post. I guess I must take a view though on the safety aspect re the navigational Gain and aid the set will afford to myself during the extended cruisies we do.

I trust you saw the Radar Arch set up we have and frankly there is little else one can do to take further preventative measures on a RIb .The points uyou have raised are all relative and one should as stated exercise caution when using this typeof equipment. At the end of the day its down to common sense.

I guess I touched on a emotive subject by placing this post , however i am glad to have got the feedback on the subject

One thing though I have not had much response on the Best Radar with a large screen for a open 9mt Rib. I was rather hoping there might be more of you out there who had use of Radar sets and their various functionalitys.

Hang in there Mr Cod prawn
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Old 20 October 2004, 08:25   #34
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Hello Mr Cod Prawn ,

What a post........you must have a degree in Microwave energy
Either way thank you for your post. I guess I must take a view though on the safety aspect re the navigational Gain and aid the set will afford to myself during the extended cruisies we do.



Hang in there Mr Cod prawn
Not far off...... particle physics to be exact.

Total waste of time though - not much call for it and the wages are shit!!!

Personally I am not a lover of bits of paper - the people getting degrees these days!

That's what I love about the computer industry - bits of paper don't mean much - it is what you can DO that counts!!!
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Old 21 October 2004, 05:49   #35
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what you can do what counts

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Originally Posted by codprawn
Not far off...... particle physics to be exact.

Total waste of time though - not much call for it and the wages are shit!!!

Personally I am not a lover of bits of paper - the people getting degrees these days!

That's what I love about the computer industry - bits of paper don't mean much - it is what you can DO that counts!!!

F**K me I am buggered then as I can not do a lot
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Old 21 October 2004, 06:53   #36
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I would FAR rather mess around with RIBs all the time!!!
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Old 21 October 2004, 08:06   #37
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Quote:
Originally Posted by codprawn
At points above or below the scanner's horizontal plane, the radiation level is lower than that measured at a corresponding point on that plane. However, it must be noted that the average radar has a rather large vertical beam width (20 to 25 degrees) and microwave radiation is beamed about 10 to 12 degrees above and below the horizontal plane. At 5 feet from the scanner and 1-1/2 foot below the scanner, the average intensity can still be in excess of the OSHA safety limit."
In that case mounting it above the console so you're right underneath it looks like a good plan!

John
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Old 21 October 2004, 10:45   #38
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In that case mounting it above the console so you're right underneath it looks like a good plan!

John
Or maybe strapping it to your head????????????????
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Old 21 October 2004, 14:51   #39
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If it was on my head it would be fine -- would probably have quite an impressive range too. Wouldn't work so well for Rogue Wave though!

John
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Old 23 October 2004, 09:09   #40
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Well what do you think of our baltic set up then

Quote:
Originally Posted by John Kennett
In that case mounting it above the console so you're right underneath it looks like a good plan!

John
John,

What is your opinion of our Baltic set up then. After much research we concluded this to be the best option on a small craft.

As you know I am also based with the RNLI at Sheerness and on our all weather lifeboat the Trent class the open radome is only just out of hands reach above our heads . The same goes for the baltic Rib.



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