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Radome mounting question

Old 03-06-2013, 06:07 AM
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Default Radome mounting question

I will be mounting (or am thinking about it) a garmin gmr 18 HD radome on the T hardtop of my 25 ft center console (EW 245cc). Question is whether I really need to put it on a 5/6 pedestal mount (with or without a 4 deg down wedge)? In looking at pictures of similar installations & boats I've seen some mounted on pedestals, others pretty much flush mounted to the hardtop. I really don't want to put it on a pedestal as I don't really like the way it looks. I've done all the geometry about the different angles and how far out you'll pick up objects etc (4 deg wedge cuts distance by about 20 ft or so: from 60 to about 40 ft using the garmin 25 deg horizontal signal). So the questions are:

1. if flush mounted to the hardtop (about 2 -3 ft from the tops front edge) will the signal get through that forward edge of the hardtop - or be noticeably obstructed)?

2. does the 4 deg wedge make any real difference real world (from those of you experienced with this set up) running at speed? (If visibility is real poor I'd be running off plane anyway).

From what I can see (and during a test ride) the EW 245cc doesn't appear to ride significantly bow high at cruise - but bow does come up a little. Appreciate hearing from others experiences, thanks
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Old 03-06-2013, 06:15 AM
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as long as the bow does not come up significantly you should be fine without either add on. my 28cc might as well be on the trailer is is so flat when on plane so i did not go with a wedge. i went with a pedestal because i have a raft mounted aft of the dome and wanted to ensure 360^ visibility.

think about what else is on your top. is it canvas or hard? If it is a hard top with some bow rise you might want to consider the pedestal. most dome manufacturers have suggested mounting positions based on the power of the dome and the setup they are mounted to that can be had on their website. I don't believe a canvas ttop with an aluminum frame and a couple of antennas will effect the beams performance. if that was the case every radar would be mounted on a bow pulpit or at the highest point on the boat without obstruction.
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Old 03-06-2013, 09:08 AM
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the higher it is the better,as for as a wedge how fast do you go in the fog when you need it the most
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Old 03-06-2013, 02:38 PM
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Originally Posted by GWC3 View Post
I will be mounting (or am thinking about it) a garmin gmr 18 HD radome on the T hardtop of my 25 ft center console (EW 245cc). Question is whether I really need to put it on a 5/6 pedestal mount (with or without a 4 deg down wedge)? In looking at pictures of similar installations & boats I've seen some mounted on pedestals, others pretty much flush mounted to the hardtop. I really don't want to put it on a pedestal as I don't really like the way it looks.
Are you buying this RADAR system as a tool, which you would presumably want to function as well as possible? Or as an ornament?


I've done all the geometry about the different angles and how far out you'll pick up objects etc (4 deg wedge cuts distance by about 20 ft or so: from 60 to about 40 ft using the garmin 25 deg horizontal signal).
You are reading too much into those specs. The nominal beamwidths (in BOTH directions) are just that -- nominal, and based on the -3dB points. The actual radiation patterns are a LOT "messier" than the simplistic numbers would imply, especially if those numbers are taken too literally or treated as an "all or nothing" proposition.


So the questions are:

1. if flush mounted to the hardtop (about 2 -3 ft from the tops front edge) will the signal get through that forward edge of the hardtop - or be noticeably obstructed)?
It's not really a matter of the signal "getting through". It's more about keeping the RF beam away from other objects (like GPS antennas & etc.) with which they might interfere; and also about these various obstructions creating reflections and diffusing both the transmitted beam and the return echos, thus making an already pretty crappy-performing RADAR's job that much more difficult.


2. does the 4 deg wedge make any real difference real world (from those of you experienced with this set up) running at speed? (If visibility is real poor I'd be running off plane anyway).
It is generally "at speed" when maximum range is most important. By using the wedge, you keep the forward horizon more-or-less centered within the RADAR's main radiation lobe, where its strength (and return sensitivity) is at its greatest. When you're running along in displacement mode, such as under reduced-visibility conditions, you are primarily concerned with objects much closer to you than several miles off. So again, the downward tilt helps put those objects in the strongest part of the beam. In neither case is anyone (that I know of, anyway) claiming that it will be a night-and-day difference; but if you can optimize the system for its real-world application, why WOULDN'T you do that?



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Old 03-06-2013, 03:28 PM
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You might want to ask Jeremiah at Edgewater - I bet they have a factory mount.
J.Carosella@EWBoats.com
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Old 03-06-2013, 04:14 PM
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My 2cents, I had mine mounted directly to the hard top. I added a 6 in forward leaning 4 degree angled mount as seen in my sig picand the radar performance was a night and day difference, I am now picking up much smaller targets than before. If you are adding radar you want it to perform the best it can.
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Old 03-06-2013, 04:21 PM
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If you need a nice mount, I'll sell you one for $125 plus shipping. Kind of silly to go without.
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