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Old 10-01-2020, 14:52   #1
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Radar obstruction??

I need a mounted spotlight for night travel. I'm looking at a version with a remote to change angle etc..
The only place I can mount it is on the hardtop near the front center or starboard edge and the radardome is right in that location.
So I'm wondering if it could interfere with the radar. This image is best I have. There is already a TV antenna on the port side so maybe I could mount on starboard side instead of the center.
Thoughts????
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Old 12-01-2020, 19:43   #2
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Re: Radar obstruction??

Can you put a taller mast on the radar? Anything in the way of the beam is going to block the signal coming and going. Probably not a problem on the ocean if the boat's moving around, but could mask objects in calm water.
Some older radars can get a too strong return from a close object and blow a fuse in the dome.
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Old 12-01-2020, 20:33   #3
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Re: Radar obstruction??

Quote:
Originally Posted by karavi View Post
I need a mounted spotlight for night travel. I'm looking at a version with a remote to change angle etc..
The only place I can mount it is on the hardtop near the front center or starboard edge and the radardome is right in that location.
So I'm wondering if it could interfere with the radar. This image is best I have. There is already a TV antenna on the port side so maybe I could mount on starboard side instead of the center.
Thoughts????
The real problem is not so much obstruction, the beam width tends to wrap around close in things, but you WILL get odd artifacts on your screen as the beam bounces off the nearby metal.

I sail a ketch, with the radome on the mizzen mast. If there is a strongly reflecting target off to one side, we routinely see a "ghost" return directly in front of the boat from reflections off the mainmast.
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Old 12-01-2020, 22:08   #4
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Re: Radar obstruction??

Could you mount the light on the underside of hardtop? If not, then off to the side as much as possible.
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Old 13-01-2020, 17:45   #5
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Re: Radar obstruction??

THANKS ALL....

Quote:
Originally Posted by jt11791 View Post
Could you mount the light on the underside of hardtop? If not, then off to the side as much as possible.
This is kind of what I am thinking to do., maybe not underside,,upside down, but i could build a small platform that extends out from the underside and mount it upright on that. It would move it down quite a bit. I don't think they recommend mounting these light upside down.
But i don't want reflection/glare off the bow or railing, so i am not sure.

OR.
I mount 2 on each corner of the hardtop so at least any interference wouldn't be directly in the front of the dome's scan and maybe they will be far enough.... (maybe) hopefully that will avoid any glare too.

Lepke:
Good point on being too close. maybe corner mounting two (or even just one) light would be far enough to not send a strong signal back. The mount is pretty high but I have not put a ruler to it. Right now shes shrink-wrapped.. I did some searching for mounts, but did not see any that were very tall. I have a height issue going under a bridge too, so i cant go too high. Hard to guess the height from the pic, but at least somebody thought enough to mount it off the top.

You can see a TV antennae on the top too. That came on the boat and I did not notice any problem on that side. I have removed it anyway.

This is a new-to-me boat I got last spring. I want to do all my research now and buy what I need so I hit the ground running and don't waste precious time setting this up. There was lots of discussion on this on www hulltruth. But no clear cut decisions.

Keep any more thoughts coming, I really appreciate it.
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Old 13-01-2020, 17:47   #6
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Re: Radar obstruction??

Just looked at the picture I posted and there is a boat in the background with a really tall mount. Why would that be needed, does not look like anything would be in the way mounted on that arch.???
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Old 13-01-2020, 19:03   #7
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Re: Radar obstruction??

Put it on top of the radar. I don't think you will be looking for incoming space craft or fighter jets.
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Old 14-01-2020, 06:58   #8
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Re: Radar obstruction??

Let me elaborate on what I just said. Putting it on top of the radar will place any metal out of the beam of the radar unit. Or, if you do not what to drill any holes in the plastic/fiberglass dome you can build a structure over the radar.

Any material you select to use as a structure that does not contain moisture, or has no RF reflective properties will work. Best solution would be fiberglass. To test any material, place a sample of the material in the microwave and run it on high for about a minute. If the material is cold when you remove it it passes. If the material is hot then it is absorbing the RF energy and will not work.

Be creative.
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Old 14-01-2020, 07:37   #9
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Re: Radar obstruction??

Quote:
Originally Posted by Brian.D View Post
Let me elaborate on what I just said. Putting it on top of the radar will place any metal out of the beam of the radar unit. Or, if you do not what to drill any holes in the plastic/fiberglass dome you can build a structure over the radar.

Any material you select to use as a structure that does not contain moisture, or has no RF reflective properties will work. Best solution would be fiberglass. To test any material, place a sample of the material in the microwave and run it on high for about a minute. If the material is cold when you remove it it passes. If the material is hot then it is absorbing the RF energy and will not work.

Be creative.
Hmmm. sounds reasonable. What is under the cover of the radar dome? Would I hit something even with a short screw? I assume I have to screw it on for security. So then the wiring would drape over, but I could run them in the back of the dome. Who cares what is behind me !!! haha

Only issue is again the height. I have to pass under a bridge and at some tides its close. At full high tide its a no-go. I've spec'd out a couple of lights go-light and others. I think they are like 7" tall. So any structure I add is tricky...
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Old 14-01-2020, 21:18   #10
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Re: Radar obstruction??

I would think just for now, do some testing while you are at the slip. First do a sweep with the radar to get a clear picture. Then put it on standby and take your light and put it somewhere on the coach roof. Run the radar again and see what is being shadowed.

Just try different locations before mounting the light.
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Old 14-01-2020, 21:58   #11
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Re: Radar obstruction??

I don't understand why you think you need a spotlight to run at night. It's illegal lighting, and it won't help you see much anyway, unless you want to highlight specific objects. But you have radar already for buoys and ships etc.

IMHO you just need a small docking light (for close in maneuvering) on each side of the bow just below the hull/deck joint. 7x50 binos also help for night vision.
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Old 15-01-2020, 05:27   #12
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Re: Radar obstruction??

Quote:
Originally Posted by SailFastTri View Post
I don't understand why you think you need a spotlight to run at night. It's illegal lighting, and it won't help you see much anyway, unless you want to highlight specific objects. But you have radar already for buoys and ships etc.

IMHO you just need a small docking light (for close in maneuvering) on each side of the bow just below the hull/deck joint. 7x50 binos also help for night vision.
Not trying to an wisea&&, but...
Apparently you've never boated in the Boston harbor area. It is an absolute
triple minefield of lobster pot lines, floating debris and boats with no lights. Can't risk tangling a pot line on the outboards at night...Been using a handheld for years on my smaller boat and did use it on this one, it works great.
I agree if I'm in open water there is no need, but open water is not the norm in my area.

I would not be piloting with it on constantly. Do a scan and drive for a while, but most pots do not even have a reflector on the stick. Sooo hard to see.

Docking is the easy part. No boat lights needed at all.
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Old 15-01-2020, 05:30   #13
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Re: Radar obstruction??

Quote:
Originally Posted by Brian.D View Post
I would think just for now, do some testing while you are at the slip. First do a sweep with the radar to get a clear picture. Then put it on standby and take your light and put it somewhere on the coach roof. Run the radar again and see what is being shadowed.

Just try different locations before mounting the light.
Great idea.... I think these lights are mostly plastic. So I am hopeful there wont be any interference, or maybe just a little that I can live with
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