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Old 28-11-2017, 12:42   #1
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Tilting Radar Mount

On my 28' Rhodes sloop I am looking at mounting my radome ...
I assembled this Furuno 1621 from parts for $225 - seems to work pretty well. So, I want to avoid too much anti-righting-moment - and am considering mounting on the front of the mast about 8 feet above the deck. I have two practical questions:

1. Will heeling be an issue with a rigid mount? I see gimbal mounts available.

2. I am guessing this will provide about a 4 mile range to water, and 5-7 mile range to other boats? Is this about right?
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Old 28-11-2017, 15:01   #2
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Re: Tilting Radar Mount

Here's a simple calculator for the radar horizon.
Horizon calculator - radar and visual

The tilting mounts are expensive and add unneeded complication, with so excited improved I aging.
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Old 28-11-2017, 16:14   #3
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Re: Tilting Radar Mount

Quote:
Originally Posted by Paul L View Post
Here's a simple calculator for the radar horizon.
Horizon calculator - radar and visual

The tilting mounts are expensive and add unneeded complication, with so excited improved I aging.
That calculator is seriously flawed when entering feet and outputting miles.


I've always approximated with SQRT(FEET) x 1.3 to get radio horizon; I was hoping for actual reports from someone with a similar height.
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Old 28-11-2017, 17:49   #4
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Re: Tilting Radar Mount

Why do you say that. At 12 feet attenna height and zero target height you get 4.25 nm. Your calculation would be 4.5.
My 24in 4kw radar is mounted about 12 feet above the water on an aft pole. It functions fine.
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Old 28-11-2017, 19:06   #5
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Re: Tilting Radar Mount

My experience with 3 similar Furuno radars is that the vertical beam cut off is very soft, and that there is no practical issue with heeling at normal sailing angles (say <25 degrees). The articulated mount is not necessary.

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Old 28-11-2017, 19:46   #6
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Re: Tilting Radar Mount

Quote:
Originally Posted by Paul L View Post
Why do you say that. At 12 feet attenna height and zero target height you get 4.25 nm. Your calculation would be 4.5.
My 24in 4kw radar is mounted about 12 feet above the water on an aft pole. It functions fine.

I must have done something wrong - With Height1 at 10 feet, and H2 at 1 ft, (floating container) I was getting 1.2 miles. Now I'm getting 5.8 which is more like it.
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Old 29-11-2017, 10:01   #7
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Re: Tilting Radar Mount

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Why do you say that. At 12 feet attenna height and zero target height you get 4.25 nm. Your calculation would be 4.5.
My 24in 4kw radar is mounted about 12 feet above the water on an aft pole. It functions fine.
Thanks all ...

So Paul L, at 12 feet high, how far away does it typically see fishing boats?
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Old 29-11-2017, 10:12   #8
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Re: Tilting Radar Mount

Heeling is not a big issue with a rigid mount. I considered the leveling mounts a couple times but just figured they would be more trouble than they are worth. Worried about cable wear and in rough weather damping the swing too.
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Old 29-11-2017, 14:03   #9
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Re: Tilting Radar Mount

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Thanks all ...

So Paul L, at 12 feet high, how far away does it typically see fishing boats?
The biggest factor in recreational radar is the horizontal resolution. A 24 in antenna that is typical on the 4kw enclosed units has about a 2.5* resolution. An 18 antenna on the 2kw units has 5*. ( numbers taken from my memory. The 4g ones sometimes claim higher). Hres will determine how well you can distinguish​ targets. In flat conditions my system will see small fish boats at 2-3 miles. It will even show birds out at a few miles. In rough conditions, small vessels can easily get lost.
An antenna mounted low will tend to do a better job at the close in targets, such as small buoys and kayaks in a foggy channel. One mounted high will see further at the loss of some close in view.
We use our radar for 4 reasons
1. A watch band setup at 2 mile while on passages at night in busy areas
2. Tracking squalls
3. Navigation in reduced visibility
4. Measurement of the distance to land (verifying chart) and distance to close in boats.
5. Tracking boats that do not have AIS using Arpa.
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