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  #1  
Old 04-26-2011
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JRC Radar - safe usage and opinions

Hi All,

I'm purchasing a boat that comes with a JRC radar. The seller told me the model, but apparently I forgot to write it down; It's a 16 mile model from roughly 2005. I suspect it's a JRC 1000 or JRC 1500 and 2kW or less but won't be able to verify that until next week during the survey.

I've never used radar before, here in the Great Lakes, it's not that necessary so this is all new to me. I seem to recall that in my VHF course they recommended never turning on in a crowded anchorage, yet I've read a number of articles that state a small radar like the JRC I've posted above is good for checking anchor drag and navigating into the anchorage. My question is, what is safe and appropriate usage for this type of radar?
(Yes, I'm familiar with the inverse-square law but I'm not sure what safe power levels are.)

The radar is mounted at what I estimate to be about 20' off the water. I've read a few opinions that 20'+/- is the correct height, others suggested 12' for a low-power, close-up radar like the model above. I doubt I will change the placement but if there's a good reason, I'd like to know about it. Any thoughts?

Lastly, I've found very little information/reviews on the JRC radar models. Are these any good? On the scale of economy, mid-range and high-end, where do these fall? Any good points/bad points that I need to know? Any and all info and opinions are welcome.

Thanks,
J.
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Old 04-27-2011
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I had a 16 mi on a previous boat and was pleased with it,never any trouble.Mounted aprox. 10 ft on mast pole on stern.marc
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Old 04-28-2011
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I have a JRC 1000 on my yacht. Still getting use to it, it's mounted on a pole about 12ft off the deck. I've read most of the manual & do not recall any warning about not using it in crowded anchorages.

I do not believe it would be very useful for entering crowded anchorages as when I was testing it over Xmas it was having a hard time picking up fibreglass yachts. Picks up large steel ships at night real well, which is where I see I will be using it most often, especially with the alarm setting when I am single handing.

Note that they draw a fair bit of power, I almost flattened my batteries when I was playing with it for a couple of hours.

On whether it's a good radar, hav'nt got a clue, mine came with the boat as well.

If you hav'nt got a manual PM me with an email address as I have an electronic copy of the manual (JRC1000 mk2)

Ilenart
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Old 04-28-2011
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In a harbor you will get too much scatter,will pu fiberglass just fine.marc
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Old 04-28-2011
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Hi guys, thanks for the feedback.
Ilenart, the idea proposed for using radar in a crowded anchorage was to take points from land to ensure that you didn't drag any distance into other boats. It wasn't so much about seeing the other boats - as you can see them with your eyes - but using it for drag-alerts when the radar targets on shore changed proximity to you.

That's a good point about power usage. I guess leaving it on over night for anchor watch will be out of the question.

Thanks Marc. My little 26' contessa likely doesn't have room for a stern pole, so I'm thinking on the mast where it is now is probably going to be where it is left. 20' shouldn't be too high, no?
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Old 04-29-2011
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When I'm worried about dragging I set the depth sounder for a high & low alarm. Uses a lot less power. And if I'm really worried (like the time it was blowing 25 knots and a reef was 50ft behind the yacht) I would also set the alarm on the GPS.

Ilenart
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Old 04-29-2011
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I have a JRC1000 - it has a small scanner but it works just fine.

Be sensitive to changes on the adjustments because small adjustments can make big changes and its not difficult to lose your way and end up with an unreadable picture.

Mine was also with the boat when I got it, on a pole above the transom. Yours on the mast is probably better and within reason, higher is better.

But it's a nice little unit for me - I am not a radar fan and it has helped a few times identifying the distance off and course of ships out there. I rarely use it for anything else
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Old 05-06-2011
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Now that I have confirmed that it is a JRC Radar 1000 (not MkII), I e-mailed JRC this morning and received an almost-immediate response (Terrific!).

In answer to my question about safety and safe usage in a crowded harbour, the reply is, "This antenna puts out 1KW of power, that’s about equivalent to a small microwave. I would not be concerned."

He was gracious enough to send along a PDF copy of the manual so hopefully that will answer the other questions I asked above.
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Old 05-06-2011
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Jordan, radar is microwave radiation and "safe" is a much debated term when it comes to microwave exposure. The FCC has limits, and there are calculator for frequency and exposure to determine how much is "safe" according to their standards, but Canada and the EU and I presume even the Bulgarians have their own standards, usually very different ones.

So, how much is safe? Arguably, none. Unless you need some to prevent bigger issues, like t-boning the next boat in the fog and sinking it.

I think if you look around online you should be able to turn up some of the exposure calculators (or the simple formulas to do the calculations) and then a call to JVC should give you the actual power output and beamspread of your radar. Given the height of the antenna and the angle of the beamspread, you'll know whether you are nuking your own foredeck crew, or just the guys on the next mooring.
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Old 05-06-2011
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heh, yes. I know about RF exposure and the debates - that's why I asked the initial question. And yes, our Health Canada has their Safety Code 6 and that confuses the heck out of me.

As for the foredeck, or more relevantly the cockpit crew since the mast is more fore than aft, that was a good idea to check. The manual claims a 'vertical beam width' of '30', which I take to mean 30 degrees and I must assume that's 30degrees down from the horizontal, which means at 20' above the deck, it will hit the deck height about 34.65' away from the mast. Considering the boat is 26' long, then I expect we're safe. Even a 6' man standing on the transom won't be able to reach the RF beam so looks like my crew and I will be safe.

Now for those around the boat, I don't know how to calculate the exposure so your idea of using an online exposure calculator is fantastic. This one ( Results - Power Density Calculator ) claims the following safe distances...
Controlled environment: 8.5 - 10.5ft
Uncontrolled environment: 12 - 23.4ft
(variation occurs given the 1kW to 1.5kW potential output as well as the ground-reflection included or excluded)
If we make the leap that the site is accurate, that means that only somebody flying over my deck fore&aft or rafted to my boat and up the mast will be in danger.

I think once we factor in the amount of time exposed to a pulse radar, then that makes me feel even more comfortable using it, if necessary, in closer quarters.

I'll go check some other calculators to see if I get different results.
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