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Old 26-08-2015, 23:50   #31
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Re: Radar Height and Range

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Originally Posted by Cadence View Post
. . . dirt cheap so why not have one. . . .
Maybe dirt cheap to you but for some, like me, it would be a serious chunck of change.

The minimum cost radar unit I can find new is the Furuno 1623 at $1421 plus tax plus secondary costs for mounting and upgrading the power system to support its use. Let's call it $2k minimum installed if I did it myself.
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Old 27-08-2015, 00:39   #32
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Re: Radar Height and Range

Here is a page about the dipping point--distance, etc. Scroll down on the page.

Marine navigation courses: Running fixes and sextant angles: 5 piloting.
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Old 27-08-2015, 07:33   #33
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Re: Radar Height and Range

I read somewhere that Broadbandscanners .Do not activate rescebeacons and raconlighouse.Maybe anyone no.
(My English sucks)


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Old 27-08-2015, 09:14   #34
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Re: Radar Height and Range

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Originally Posted by Jonte View Post
I read somewhere that Broadbandscanners .Do not activate rescebeacons and raconlighouse.Maybe anyone no.
(My English sucks)


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I'm not sure what your asking, but I do think there are essentially Radar detectors on some boats that are used to detect other Radars and of course other boats. I do not believe that the radiated power of a frequency modulated, continuous wave Radar is high enough to be detected very easily. Matter of fact, I think they are very difficult to detect, requiring very expensive equipment to do so.
So if there are lighthouses or other equipment that detect Radar signals, I doubt they would be detected.
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Old 27-08-2015, 09:18   #35
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Re: Radar Height and Range

As a cruiser with a a 30 foot Catalina, I am going to mount my 4G radar unit on a pole about 11 feet off the water on the Port side.

My reasons for this are: Most times if you need the radar in the Pacific NW it is due to fog. You are motoring and not under sail. If you are inside, waves usually do not present a problem. The effective range I need is just off the boat out to say 2 miles. This is all I need. I want to see other boats and shipping traffic. This goes along with my AIS.

Second big reason is I do not need anything more running up and down the inside of the mast. There is enough stuff in there now and I want to see my connection between the radar unit and it's control box.

My two cents worth....
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Old 27-08-2015, 09:42   #36
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Re: Radar Height and Range

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Originally Posted by a64pilot View Post
I'm not sure what your asking, but I do think there are essentially Radar detectors on some boats that are used to detect other Radars and of course other boats. I do not believe that the radiated power of a frequency modulated, continuous wave Radar is high enough to be detected very easily. Matter of fact, I think they are very difficult to detect, requiring very expensive equipment to do so.
So if there are lighthouses or other equipment that detect Radar signals, I doubt they would be detected.
SART devices and RACON Lighthouses Can be Activated with Radar pulses. But i dont think Broadbandradar Can Do that. I am not sure thats why i ask. Sorry Maybe of topic.

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Old 27-08-2015, 09:54   #37
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Re: Radar Height and Range

I have read all the comments and I appreciate all the help.
I think I will keep it on the questus. The things I need to see far off are big and high (weather and big boats) so their height makes up for me not having as much height. Also easier to get to is a factor. Again, I appreciate all the comments.
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Old 27-08-2015, 11:09   #38
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Re: Radar Height and Range

Gimbaling the radar dome on the back stay works great.


A photo of one such setup--not my first choice--doesn't look beefy enough.
Seaview SLB1 Self Leveling Backstay Kit

Previous C.F. thread on backstay installation

Backstay- vs Pole-Mounted Radar
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Old 27-08-2015, 12:08   #39
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Re: Radar Height and Range

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SART devices and RACON Lighthouses Can be Activated with Radar pulses. But i dont think Broadbandradar Can Do that. I am not sure thats why i ask. Sorry Maybe of topic.

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Maybe a little off topic, but threads always drift and in my opinion it's often a good thing as if they didn't most would die pretty quick.

I'm also almost certain your correct, the radiated power of a FMCW Radar is very low, I seriously doubt anything meant to be activated by Radar would be activated.
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Old 27-08-2015, 12:47   #40
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Re: Radar Height and Range

Quote:
Originally Posted by Adelie View Post
Maybe dirt cheap to you but for some, like me, it would be a serious chunck of change.

The minimum cost radar unit I can find new is the Furuno 1623 at $1421 plus tax plus secondary costs for mounting and upgrading the power system to support its use. Let's call it $2k minimum installed if I did it myself.
Sorry if I hit a nerve. I was speaking of days of yore and the cost.
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Old 30-08-2015, 06:44   #41
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Re: Radar Height and Range

The radar lobe are usually ±15° vertically. That means that it goes 15° below the horizon. If you mount the dome on a pole in the aft of the boat 2.7 m above the waterline, the lobe comes down to the waterline 10 m forward of the pole. (10 m x tan(15°) = 2.7 m). On a 13.8 m boat it means that the front cabin is in the field.

The power in the signal of a broadband radar is a factor 10000 lower than on a pulse radar. That’s so low that either the SART or RACON will be activated. But since energy is power multiplied by time, and the broadband radar transmits continuously while the pulse radar transmits with very short pulses, the energy in the signal I “only” a factor 10 lower. If you believe that the field from a radar ain’t healthy, then is the broadband radar not a solution.

I have seen many boats that have mounted the dome on a pole in exact the same height as the boom. When they sail with wind from astern and have the boom out across I believe that the boom can interfere with the radar considerably.

Once I was sailing over the Atlantic and we have hade a lot of wind for some time so the waves hade come up in height a little. When I was standing in the cockpit with my eyes about 2.5 m above the waterline I saw nothing of the boat that we sailed along with even though they had a 20 m high mast. It dose not mean that the waves was 20 m high but more that my low eye level limit the visibility considerably.

I have a 0.45 m dome that have a weight of 5 kg. Either if you mount on a pole or on the mast, it need to be a quite strong place. If it’s mounted in the mast, a natural strong place I where there are spreaders. Since you don’t wont to have too much weight high up in the mast, the lowest spreader pair is suitable.

In my home harbour we take of the mast when wee take up the boot for the winter and I have problem whit the dome cable every year. Furuno have a stand-alone system where the dome only has a power cable and the signal goes via wifi to the ipad that works as display.
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