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Garmin 24" HD Radom Vs 48" Open Array?

Old 05-17-2008, 07:00 PM
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Default Garmin 24" HD Radom Vs 48" Open Array?

Has anyone done any comparisons of these two units side by side. They are both powered at 4kw. The 48" open array has a much smaller beamwidth at 1.8 degree's VS the 3.6 on the 24" HD dome. BUT, the 24" HD is, of course HD (High Density), and supposedly offers better target separation.

So how do they compare?? The open array is almost twice the money, is it worth it?

I'd love to see a side by side comparison of these. Is anyone from Garmion on here??
Old 05-18-2008, 10:36 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

Wow, can't beleive nobody has conmpared these side by side, including Garmin themselves??

Garmin has great side by side comparison of the HD and non-HD dome's, but nothing on the open array vs HD.

Could it be that is because the open array is a rippoff at twice the price now that the HD domes are available?
Old 05-18-2008, 06:13 PM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

Can't give you real data on how the HD and non-HD compare but I would guess that the hor beamwidth of the open array being half of what the dome has that the open array would have better target separation.
Old 05-18-2008, 09:42 PM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

That's what you would expect, BUT, on Garmins support website, they compare the 24" NON HD dome to the new 24" HD dome, and the HD seems to work as if it has 1/2 the beamwidth of the other one even though they are the same.

So that is the reason for the question. Maybe it then works as good as the open array???

Old 05-18-2008, 11:29 PM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

Don't be fooled by the marketing hype surrounding "HD" radars. The underlying technology and indeed the tranmitting and receiving hardware is the same as the "old" radars. What the technology does is enhance the signal processing, filtering, and automated operation to improve performance for the average user. I had an interesting conversation with a top Furuno engineer on this subject. He told me that a well-trained, experienced radar operator could get just as good a "picture" as their new "UHD" radars by manually tuning their older radars But he added that very few people have that level of training and experience so for the average boater, the UHD will display a much better picture. The added processing power also allows the UHD versions to do cool things such as simultaneously operate on two ranges that the older units can't do.


A 24" dome cannot produce the target resolution of a 4' open array -- the laws of physics make it impossible. But a lot depends upon what you are trying to do with the unit. If what you want is basic collision avoidance while navigating in fog or at night, the dome will get the job done and the "HD" version will make it much easier for you to ensure that the radar is set properly by doing the work for you. But if you need to find smaller targets, operate at greater ranges, look for birds, etc, etc, the open array will be a better choice. Also note that on a smaller boat with a lower mounting height and more motion in rough seas, the performance benefits of the large array are not as great.


I am sure Garmin will be offering an HD version of the open array at some point so why not just wait a while if you need the greater capabilities of the open array?
Old 05-19-2008, 04:40 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

Its all about beam width and power - beam width for target separation and power for distance. Smaller beam width, which means a longer array and more power are better. This is why big ships carry 75 kw units with 10' antennas. Garmin doesn't compare the 24" HD dome to the 4' open array, because there is no comparision; with double the beam width the 24" dome has half the resolution of the 4' array. 4kw gives an honest and usable 16 mile range, which is about all you can see on a recreational boat with the antenna mounted 8-12' above the water.
Old 05-19-2008, 08:51 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

Thanks guys, that's exactly what I thought, but I needed to here it from elsewhere....

I don't need long range, as noted it will be mounted on a hartop about 1o or so feet above the water so I'm not going to get great distance anyway. But I DO want good detail, ability to find birds maybe, see small plastic bouys in the bay clearly. So I think I will probably go with the array

I currently have the small 2kw dome from Raymarine that I'm happy with, but I would like a little better resolution.
Old 05-19-2008, 09:42 AM
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Default RE: Garmin 24" HD Radom Vs 48" Open Array?

I looked at both of the units for my new boat. The dealer actually talked me out of spending the extra money for the open. I went with the 24" HD series. I took the boat out this weekend fishing and was VERY pleased with the 24" HD. I have always had Garmin and just had the "non HD" on my last '07 Contender (lastest technology at the time). For over half the money, my bet is the 24" HD. The new HD series is a huge difference over the "non". They didn't have to sell me a bag of tricks! I have seen it for myself! The 24" HD is a really nice step up over the old series.
Old 05-19-2008, 09:49 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

that is a great post nomans. i think that is the straight poop rather than doctored up marketing hype.

i'm suspect of garmin's comparison...if you look at the noise around the boat in the 'HD' picture, it looks like the gain is just turned up...which would explain the bigger & increased number of targets...





as nomans said, it seems like the 'HD' might really just be an improvement on the operating characteristics of the 'auto' mode. i have found that the non-HD garmin radar will indeed miss targets in the auto mode. operating outside of auto mode, i have been impressed with it. of course, a lot of people are probably just running in auto mode, so HD may indeed be an upgraded for many.
Old 05-19-2008, 10:20 PM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

Of course the HD dome will be better than a non HD dome. No doubt Garmin has compared the performance for those radar antennas. The question is why isn't that information published. My point was the same as NoMans - the narrower beamwidth of the open array will give better target separation.
Old 05-19-2008, 11:11 PM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

According to a Garmin tech rep I spoke with today, the 24" HD dome performs the same or better than the 4' open array at close distances. The only benifit of the open array over the 24" dome right now, is distance, and most of us have them mounted 10', so your going to run out of horizon before you run out of power.
Old 05-20-2008, 09:22 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

sickcat - 5/20/2008 1:20 AM

Of course the HD dome will be better than a non HD dome. No doubt Garmin has compared the performance for those radar antennas. The question is why isn't that information published. My point was the same as NoMans - the narrower beamwidth of the open array will give better target separation.
??
they did compare them, and they did publish it. it is posted on their website.

however, it appears to be more of a test of the auto mode than anything else to me. (don't get me wrong...it needed improvement)

Old 05-20-2008, 09:39 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

I agree with most that have posted here. I have the 18 HD. It seems to work great, but I don't have anything else to base it on. The fact that Auto mode works better for me is good since it is dificult to fine tune a radar in a 20 Foot CC while going 35 MPH in anything but flat calm seas. So for me I generally use AUTO mode and it seems to be working great so far.
Old 05-20-2008, 10:24 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

GravyBoat - 5/20/2008 12:39 PM

I agree with most that have posted here. I have the 18 HD. It seems to work great, but I don't have anything else to base it on. The fact that Auto mode works better for me is good since it is dificult to fine tune a radar in a 20 Foot CC while going 35 MPH in anything but flat calm seas. So for me I generally use AUTO mode and it seems to be working great so far.
GREAT point!!
Old 05-20-2008, 11:36 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

chainsaw42 - 5/19/2008 9:49 AM



that is a great post nomans. i think that is the straight poop rather than doctored up marketing hype.

i'm suspect of garmin's comparison...if you look at the noise around the boat in the 'HD' picture, it looks like the gain is just turned up...which would explain the bigger & increased number of targets...





as nomans said, it seems like the 'HD' might really just be an improvement on the operating characteristics of the 'auto' mode. i have found that the non-HD garmin radar will indeed miss targets in the auto mode. operating outside of auto mode, i have been impressed with it. of course, a lot of people are probably just running in auto mode, so HD may indeed be an upgraded for many.
THANKS! thats a great comparison......and i think seals the deal for me that the way to go is to spend a bit more and get the HD. As a complete radar newbie, im sure the "auto' setting is going to be my setting of choice for at least a while.
Old 05-20-2008, 08:52 PM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

chainsaw42 - 5/20/2008 9:22 AM
sickcat - 5/20/2008 1:20 AM Of course the HD dome will be better than a non HD dome. No doubt Garmin has compared the performance for those radar antennas. The question is why isn't that information published. My point was the same as NoMans - the narrower beam width of the open array will give better target separation.
?? they did compare them, and they did publish it. it is posted on their website. however, it appears to be more of a test of the auto mode than anything else to me. (don't get me wrong...it needed improvement)
I see my statement was unclear (pun intended). The OP was trying to compare the performance of the GMR24HD and the GMR404. Thoseare the two antennas I was refering to when I said the Garmin has compared them but not published any info on it. I saw where they compare the GMR41 and the GMR24HD and agree it is pretty vague. If you do the "manual" compare of the GMR24HD and the GMR404/406 all it really says is:

"High definition (outstanding target separation with less screen clutter):"

noting that the GMR404/406 were not HD and the GMR24HD of course was HD. When I compare the 1.8 and 1.1 degrees of hor beam width of the GMR404 and GMR406 respectively with the 3.6 degrees of hor beam width on the GMR24HD I would have a hard time believing that using manual settings to maximize the tuning of all 3 of those antennas that the GMR24HD would have better performance than those the open arrays. I can certainly see the GMR24HD outperforming the GMR24 especially on auto but you can't synthesize narrower beam width.
Old 05-21-2008, 07:50 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

I don't have any experience with the Garmin 404/406, but if their HD 24" dome is a good as the 404/406, it means Garmin's open array antennas are crap. Simple physics makes it impossible for a similarly powered 2' array to match or exceed the performance of a 4' or 6' array.
Old 05-21-2008, 08:05 AM
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Default Re: Garmin 24" HD Radom Vs 48" Open Array?

I would LOVE to see Garmin jump in here!!!

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