4G Radar - Gimballed mount worth it?

[Schooner Chandlery]

We have the B&G 4G radar. Ours is mounted about 20ft above the water. Since it is mounted beside the mast (not in front of it because our gaff boom would have hit it there...) we did not have a choice to make regarding gimbal or not. Had we had the opportunity to mount it on the forward side of the mast--we'd have gone for the gimbal (I think!) but it works fine as it is. We've used it in very rolly conditions -- big quartering seas with rolls from 10-15 deg to port and then to starboard, back and forth, back and forth. Doesn't seem to make a big difference to the radar. We seldom sail at a constant heel but if so it is usually between 5 and 10 degrees no more than that because it's not efficient/leeway.

Ours was installed right before a big trip to the PNW/AK and we were happy to have it, for sure! Blog link

[Only Time]

Questus is the original manufacturer of the gimbaled mounts and has a great solution whether it is on the backstay, radar pole or mast. No matter how you look at it, it makes your radar more effective. You can find more info at: Questus Marine radar automatic leveling system prevents target loss when heeling. I have been using one for years without any problems.

[colemj]

Originally Posted by ErBrown

OK, this is likely a very stupid question, but I'm curious. Since our backstay is used for the SSB, I'm hesitant to mount radar there and a pole mount above panels will result in shading. What about mounting the radar lower maybe to the side of and on the same plane as the panels to eliminate shading? The panels will be mounted flat and are fairly thin, particularly when compared to the mast (where we've been planning to mount).

I'm picturing something like this. Arch with 3 panels mounted in a fore and aft orientation. With radar and wind-gen offset to the starboard side. Radar below wind-gen. The only realistic place for us to mount the wind gen is on the arch, which will result in some shading, so my goal is to minimize shading potential from the radar. Our sail maker is trying to steer us away from mast mounting, which had been the plan all along.

Stupid?

If you mount your radar on the arch using an aft offset mount (short pole slanted backwards), the only shading will be when the sun is very low on the horizon directly behind you, when it really doesn't matter much.

Mark

[wrwakefield]

Originally Posted by rcassano

Hello Bill,

My radar is a GMR24HD mounted 23'9" above deck. It's just slightly above the spreaders. Not sure how much more to add for "above waterline" - maybe five feet or so. When I said "Beautifully clear" I was certainly being sarcastic about the lack of image on the chartplotter screen. My observation was some years ago, but I remember seeing commercial traffic on the water and not seeing it on radar while healed over under sail. After installing the Scanstrut on the mast I felt we had much more to deal with as the chartplotter radar screen looked busy and we had to pay close attention. None of my observations are scientific or measured in any way.
I can say that I felt like I was missing radar traffic when the dome was fixed vs gimbaled.

The Scanstrut is a little temperamental and occasionally needs to be re-leveled. This is easy to do but requires a trip up the mast. I don't think having a gimbaled mounted dome has a down side. I bought the Scanstrut because it just made sense to me to have a level radar looking at a level horizon.

Thank you for the additional information, Rcassano. I appreciate you taking the time.

As I had mentioned in my first post in this thread, I can absolutely see the advantage of leveling the Radome when it is either lower to the water or to off-set heeling angles that exceed half of the vertical beam width of the RADAR in question.

From your description, it sounds like your your need for leveling is due to the latter circumstance (angle of heel) and I wouldn't hesitate to do the same as you have given those circumstances.

On a vessel I had in the past [Valiant Esprit 37] I had a pole mount Radome and had designed and fabricated a manual leveling system that worked quite well [unless I forgot to re-level the Radome after changing tacks or after stowing the sails...]

Thanks again.

Cheers!

Bill

[rourkeh]

The people who don't want to spend the money on self leveling mount will find lots of reasons why they don't need it.
The people who don't care about spending the money will find lots of reasons for buying it.
The science of the question answers the question for you.
The beam you are projecting from your radar is similar in many ways to a flat flashlight beam, if you want a large portion of your beam pointing into the water and up at the sky then get a fixed mount for your mast. Radar antenna arrays are MADE to be mounted and kept horizontal for a reason. This question is best answered by speaking with the manufacturer, ask them if it is a good idea to mount the antenna array sideways. See what they say.

[ErBrown]

Originally Posted by rourkeh

This question is best answered by speaking with the manufacturer, ask them if it is a good idea to mount the antenna array sideways. See what they say.

I actually did reach out to B&G and they won't give a recommendation one way or the other. Saying it was a "personal decision". So not a lot of help there.

If considering something like Mark recommended with getting the dome lower and offset from the panels on the arch. If I go this route then a leveling mount seems to be a good option, if I can find something cost effective. $1k for a mount just hurts for some reason.

[a64pilot]

I called B&G when I was deciding where to mount mine, and they recommended pole mounting on the stern, saying there was no performance advantage on the mast and if I ever had to work on it, I'd be glad it was pole mounted.
But I didn't ask about an articulated mount. I'd think if it boosted performance they would recommend it?
Why wouldn't you recommend something that made your product work better?

[darrelweb]

Originally Posted by a64pilot

I called B&G when I was deciding where to mount mine, and they recommended pole mounting on the stern, saying there was no performance advantage on the mast and if I ever had to work on it, I'd be glad it was pole mounted.
But I didn't ask about an articulated mount. I'd think if it boosted performance they would recommend it?
Why wouldn't you recommend something that made your product work better?

Most times you are not sailing when you are really in need of your radar. Such as in the fog. So far l have found pole mount works just fine. Besides those mounts are costly....my two cents worth, OK.

[SV DestinyAscen]

Doesn't this really depend on what you're looking to get out of radar?

If you're expecting it to detect a floating bouy 10 meters away on windward while you're heeled over 15° persistent, it'll probably disappear as it gets closer.

If you're looking to help with poor visibility/night time weather, then it probably doesn't matter. Convective clouds won't disappear.

The 4G solid state radars have so much data processing capabilities you can adjust for sea state and it'll help you filter out reflection off sea vs hard contacts.

[BigAl.NZ]

Coming in to this thread a bit late, but its been good reading as our existing radar is on a transom pole and the new (Quantum 2) one I will put on mast.

Not decided on gimbal yet...

The two main things for me going against gimbal based mount is cable chaffe and cost. Can't do much about the cost.

Re the cable chaffe, many new radars are Wifi now, so that would limit the cable chaffe to the power wire. Is it a standard power wire or some $$ Raymarine power wire...not sure yet as I don't have the unit.

Also, in the S.Pacific vs N.America fog isn't normally an issue, its more used when on night passages when under sail for collision avoidance, so heel in an issue.

[darrelweb]

Hi there.
Here in the NW, l only use the radar when in fog and under power. I do not sail in fog.
Open ocean is another thing, but im like you, the cost of a gimballed mount is just crazy.
I would tend to put my faith in the person on watch avoiding anything that is floating.
Just my two cents worth.
Darrel

[True Kiwi]

Originally Posted by rcassano

Hello Bill,



My radar is a GMR24HD mounted 23'9" above deck. It's just slightly above the spreaders. Not sure how much more to add for "above waterline" - maybe five feet or so. When I said "Beautifully clear" I was certainly being sarcastic about the lack of image on the chartplotter screen. My observation was some years ago, but I remember seeing commercial traffic on the water and not seeing it on radar while healed over under sail. After installing the Scanstrut on the mast I felt we had much more to deal with as the chartplotter radar screen looked busy and we had to pay close attention. None of my observations are scientific or measured in any way.

I can say that I felt like I was missing radar traffic when the dome was fixed vs gimbaled.



The Scanstrut is a little temperamental and occasionally needs to be re-leveled. This is easy to do but requires a trip up the mast. I don't think having a gimbaled mounted dome has a down side. I bought the Scanstrut because it just made sense to me to have a level radar looking at a level horizon.

Re: "When I did the install I shielded the power and data cable with split loom and wire ties."
Could you please give me more detail on this and how you did it?
What diameter Loom and how long? Any problems snaking into the mast?
Do you have an in mast furling rig?
I am getting a gimbal radar mount and trying to figure out the best way to install.
Any advice would be appreciated.
Thanks
Pete.

[bdgWesternMass]

Originally Posted by rourkeh

The people who don't want to spend the money on self leveling mount will find lots of reasons why they don't need it.
The people who don't care about spending the money will find lots of reasons for buying it.
The science of the question answers the question for you.
The beam you are projecting from your radar is similar in many ways to a flat flashlight beam, if you want a large portion of your beam pointing into the water and up at the sky then get a fixed mount for your mast. Radar antenna arrays are MADE to be mounted and kept horizontal for a reason. This question is best answered by speaking with the manufacturer, ask them if it is a good idea to mount the antenna array sideways. See what they say.

This all sounds like a solid logical footing but I think the conclusion is too general. The aperture size of your "flashlight" beam has not been considered. The notion of mounting it sideways is too hyperbolic for real consideration.

I don't have any answer.

I think if the aperture size of the RADAR is large enough, that the digital processing could compensate for heeling.

This is the same technique as digital image stabilization and I know is used in at least some 4G (fourth generation) phased array RADAR.

I'm sorry about this nitpicking but I hope to keep technical discussions precise.

All good things,

Ben