I am building a short tower for my radar on my Hewes Ocean Pro. What is a common angle for the radome so that it tilts in the right direction when on plane? Does anyone actually have theirs tilted or do you just go with 0 degrees? I'd like to build the angle into the tower instead of using shims. I was thinking 4 degrees. I currently have a temporary solution I've been using for a couple years and I think it is about 2-3 degrees (I just used washers on the back two bolts) and it works good. Curious to get feedback from others. Thanks!
Radome angle
- Thread starter bpsuls
- Start date
BCI
Well-Known Member
4 degree wedges and masts here for ideas;
https://www.seaviewglobal.com/collections/popular-products
https://www.seaviewglobal.com/collections/popular-products
casper5280
Crew Member
4 degrees is the norm for most radar installs but I would be more concerned with getting it as high as possible. Proper installation plays a big role in maximizing the performance of marine radar domes.
To perform effectively, mount the radar dome high enough to give it an unfettered, level and full-circle view of the horizon, but not so high as to be adversely affected by the boat’s pitching and rolling. The higher the elevation, the greater the radar range, but too much elevation can hamper close-in performance because the beam will shoot over targets rather than at them. First off, getting the dome above head level is a must because you don't want to bake yourself and your crew with microwave pulses every time you use the radar. (This is less of an issue with Broadband, which emits a much lower burst of power.) Beyond the safety concerns, height is important because the biggest limiting factor relating to radar's performance is the Earth's curvature. Those microwave beams can't be bent to follow that curvature, so the height of your radar antennas and the height of the target you're looking for will always limit the distance your radar can see. A radar mounted 12 feet off the water might first spot a small powerboat, with a maximum height of 9 feet, at a distance of just under 8 nautical miles. No matter how big and powerful your radar may be, no matter how much it cost, you can never expect it to see beyond that. Nor will it commonly see all the way out to this range; this is merely the maximum you can hope for. Target shape and density, atmospheric conditions, and other variables usually will have an effect on range as well. The radar should be installed so that it’s level while the boat is underway. The bow angle is often greater when the boat is running at speed than when it’s at rest. So, if you mount the dome level with the boat at rest, the radar beam will be aimed upward while underway. To find the correct angle, use an inclinometer or phone app to determine the average bow angle at cruising speed for your boat. Use a wedge adapter to tilt the forward portion of the dome downward to compensate for bow rise.
To perform effectively, mount the radar dome high enough to give it an unfettered, level and full-circle view of the horizon, but not so high as to be adversely affected by the boat’s pitching and rolling. The higher the elevation, the greater the radar range, but too much elevation can hamper close-in performance because the beam will shoot over targets rather than at them. First off, getting the dome above head level is a must because you don't want to bake yourself and your crew with microwave pulses every time you use the radar. (This is less of an issue with Broadband, which emits a much lower burst of power.) Beyond the safety concerns, height is important because the biggest limiting factor relating to radar's performance is the Earth's curvature. Those microwave beams can't be bent to follow that curvature, so the height of your radar antennas and the height of the target you're looking for will always limit the distance your radar can see. A radar mounted 12 feet off the water might first spot a small powerboat, with a maximum height of 9 feet, at a distance of just under 8 nautical miles. No matter how big and powerful your radar may be, no matter how much it cost, you can never expect it to see beyond that. Nor will it commonly see all the way out to this range; this is merely the maximum you can hope for. Target shape and density, atmospheric conditions, and other variables usually will have an effect on range as well. The radar should be installed so that it’s level while the boat is underway. The bow angle is often greater when the boat is running at speed than when it’s at rest. So, if you mount the dome level with the boat at rest, the radar beam will be aimed upward while underway. To find the correct angle, use an inclinometer or phone app to determine the average bow angle at cruising speed for your boat. Use a wedge adapter to tilt the forward portion of the dome downward to compensate for bow rise.
I have a 22’ Hewes OP with hardtop. My Garmin 18xHD radome sits atop a 4 degree wedge and works very well. Can see boats no problem cruising at 25kt as well as when trolling in the fog amongst fellow combatants.
Mounted on an arch would be even better, naturally, but directly mounted to the roof also works well.
Hope this helps.
Barry
Mounted on an arch would be even better, naturally, but directly mounted to the roof also works well.
Hope this helps.
Barry
Thanks for the input, I will do 4 degrees. The added height advantage is interesting, it is the main reason for not mounting it directly. I am going to add a anchor light directly to it as well to free up some roof space where it is currently. My dome is mounted directly to the roof currently, but I can't go very high with the tower because I trailer all the time and I want to keep everything under 13 feet from the ground which is the legal limit. I don't want to have to go up there and knock it down every time I trailer, because knowing me, I'll just forget! I have the Lowrance 3G broadband.
Sharphooks
Well-Known Member
Yes, a 4 degree wedge is typical but part of the calculation on radome height is where does the radome sit in relation to your GPS puck(s) if you have any mounted on the wheelhouse roof.
Not sure of the effects of 3G broadband on a GPS puck but a traditional radome with a magnetron can fry a GPS puck.
I took that into consideration when deciding where the radome (and the radar beam) would sit in relation to my (very expensive) GPS pucks
Not sure of the effects of 3G broadband on a GPS puck but a traditional radome with a magnetron can fry a GPS puck.
I took that into consideration when deciding where the radome (and the radar beam) would sit in relation to my (very expensive) GPS pucks
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Yeah that is a good point. I ended up mounting my Point 1 flat against the roof. I have a broadband radar so it cant cook other electronics inherently by design but there are specs on how far things can be from the antenna so it does not magnetically interfere and therefore loses accuracy. I ended up downloading a magnetic field finding app with my phone to find an optimal location. Lowrance says radars have to be at least 20 inches away from the antenna but practically all boats I see always have the GPS antennas almost right next to the radars, so it must not matter too much or no one's stuff would work. Regardless I followed all the requirements just to be sure.
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That isn't quite correct. You are referring to a Faraday Cage, which will reduce fields significantly (while still allowing stable fields such as the earth's magnetism to penetrate) but even if you had one of those in your puck you still cannot put it right next to the radar and expect zero deviation. It will matter on the equipment that you use though, The Lowrance/Simrad radars use Frequency Modulated Continous Wave Radar which does not contain the giant Magnetron that traditional radars use which creates larger electromagnetic fields when in use, such as the tech that Garmin uses, for example. The magnetic deviation would be significantly less with the Lowrance (about 0.165W of energy) than the Garmin (About 4000W of energy at max). I do not know however if the pucks actually has a built in Faraday Cage or not, but none the less, I still wouldn't put a sensitive compass right next to a huge electromagnet. Magnetic fields are non linear though so even a small distance change can cause a large drop in magnetism. In terms of the GPS itself, it probably wouldn't be affected at all by the magnetism, it's really just the compass. Plus there is probably a lot of iron inside the Radome itself which you generally want to avoid placing any compass near anyways, though calibration should compensate that for the most part during your installation.
BTW the diagram I showed above is what I got with my Point 1 package last year, so its still an issue even with modern pucks.
