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Old 03-02-2021, 11:56 PM   #1
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Radar Array

Over the winter did a very pricey electronic upgrade, including full canvas upper helm and lower.
Question is has anyone done the actual degree signal from where your radar is mounted with any obstructions to water in front of your boat!
I just got new canvas and our guy put a pretty good crown on the the new roof, well low and be told it’s now affected our new radar on the arch. Have not tested as of yet, but seems they want a 20 deg beam 10 up and 10 down. We only get 2 deg in 34’.
Unobstructed view from the Array is 20” drop in 34’ from the arch, this makes the beam hit the salt in 320’ with it being installed at 16’ on our boat.
Supplier said we will have dead spots, have any of you experienced this?
Hope this makes sense or there is a simple formula?
Thanks in advance

Troy
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Old 03-03-2021, 07:26 AM   #2
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If I'm understanding you correctly, I wouldn't want my radar shooting through the canvas and metal framing of the flybridge cover.

Regarding installation, the manual will give a specification for the degrees above and below a level radar, that it sees objects. Before installing a new radar, I would determine if the mount is level with the boat tied to the dock and then compare it with speeds underway. Generally, the bow of your boat rises underway requiring the radar to be closer to level underway. The higher the radar is mounted, the tougher it will be to see objects closer to the boat. Angling the radar down in front will improve your forward vision at the expense of loosing close vision behind you.

If your avatar picture is current, I would need to raise the radar antenna to see over the canvas work. Radar angle can be modestly changed by shimming the front or the back with stainless steel flat washers.

Ted
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Old 03-03-2021, 07:50 AM   #3
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If I understand the question, sounds like you need to raise your dome up a bit. You probably needed to do it before, just became more noticeable after the new bimini.

These Edson mounts come in different heights - 6", 12", 18"

https://www.hodgesmarine.com/eds6801...ft-angled.html

From the Simrad installation manual, here's how to calculate how high your dome needs to be for clear view.

Good luck - Peter
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Old 03-03-2021, 08:05 AM   #4
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I did have this happen on my center console with a t-top. The forward aluminum tubing was well within the +/- 25*. Pretty much dead center. Yes it did affect the returns. Much worse when the boat was tilted back at <10 knots. My solution was to install a 5" height mount with a down angle as shown in the photo below. The returns went from poor to good. Here is an example:


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Old 03-03-2021, 10:46 AM   #5
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My boat has two radar antennas -- one mounted on top of the FB Hardtop, perhaps 25' above the waterline, and the second at the top of the tower -- about 40' above the waterline. The lower radar can "see" closer objects than the higher radar, but both can "see" objects much closer than math would predict. The theoretical limits (assuming a 20 degree vertical beam width, though as I recall the actual beam width is 17 degrees for my radars), the limits should be about 140' for the lower radar and 230' for the upper -- any closer and the object would be outside the radar's radiation cone. In practice, the lower radar can see as close as perhaps 90' and the upper about 150'. I think the difference is that some energy is radiated outside the cone, and it takes very little energy to light up an object that is so close.
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Old 03-07-2021, 12:01 AM   #6
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Quote:
Originally Posted by mvweebles View Post
If I understand the question, sounds like you need to raise your dome up a bit. You probably needed to do it before, just became more noticeable after the new bimini.

These Edson mounts come in different heights - 6", 12", 18"

https://www.hodgesmarine.com/eds6801...ft-angled.html

From the Simrad installation manual, here's how to calculate how high your dome needs to be for clear view.

Good luck - Peter
Attachment 115164
Thanks Weeb for proper graphs of radar beams. Much better than what I could find through Furuno.
Much appreciate everyone’s opinions.
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Old 03-07-2021, 12:29 AM   #7
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I was always taught that the radar antenna needed to 18-24" of clear space below it to work correctly.
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Old 03-07-2021, 08:13 AM   #8
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I can't say for sure but maybe do nothing till you test it.

If the only thing that had changed is the canvas setup....it shouldn't effect much but the framing might a tiny bit.

If you want closer in targets to show up,, and care a little less about things many miles away, then just a couple shims under the back of the radar may do the trick.
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Old 03-07-2021, 10:01 AM   #9
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PSN, I think your right, test it out and really see.

Being that we pulled the arch off this winter and rebuilt the inner wood structure with Purple Heart wood. Glassed 30 yrs of holes from old electronics and painted I am reluctant to do a bunch of test holes, it almost feels like a new boat looking down from the top.
I have drilled holes for the radar, which can double or be covered with any adapter I may need.
I took advantage of the winter to do so many upgrades, and now have seen the finishing of some things have slowed down where I need a specific shops expertise. The sleepy boaters are waking up, so if anything custom will have to wait.
2021 boating is 2 wks away, can’t wait to put the portable diesel heaters away and let my permanent headlamp indentation grow back.
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Old 03-07-2021, 12:53 PM   #10
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How will you know if radar is partially blocked? You can tell if it's totally fubar, but how do you know when it's partially fubar?
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Old 03-07-2021, 02:59 PM   #11
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On our boat the radar was mounted directly to the pilothouse roof in the center. We could see objects clearly at 1/4 mile, but at 1/8 mile they would blur out. We moved the antenna forward and up 24" over the roof. Now at an 1/8 mile range we can see individual barges in a tow. It was clear that the antenna was being blocked by the roof and search light.
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