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Old 26-03-2016, 03:36   #1
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Best mount for a Radar?

Hi Folks,

I'm upgrading the electronic equipment on my Najad 405 and one new entry will be a Simrad 3G Radar. I see 3 option for the mounting and would like to hear your advice on those.

1) Mount on the mast: this is the most common, however I see the following disadvantages
- can't see very short distances, let's say 10 mt from the boat, that I think it's useful when approaching a bay with fog
- Higher weight on the mast and more holes to
- Harder to reach in case of maintenance
- Lost in case of mast damage/loss

2) Mount on a pole: this is also very common. Most detractors say it's dangerous for the RF radiations, but the new radars have very low radiations, so I would not be worried. It overcomes all disadvantages of the mast mount, however I see the following other
- it has lower optical reach, hence visibility will be lower
- IMHO it looks ugly on a 40' boat

3) Mount on the back stay with self leveling support: I see this mount becoming more and more common. It has the same pros/cons of a pole mount, but it's not ugly. Has however the same disadvantage that in case of mast loss it becomes unusable.

I am personally in favor of the back stay, but have not decided yet and have friends telling me that a pole mounted radar is better considering the fact that I could use the pole for other equipment and antennas.

Your opinions and experience sharing will be greatly appreciated.

Buon vento
Paolo


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Old 26-03-2016, 22:13   #2
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Re: Best mount for a Radar?

I have a back stay mounted self leveling Questus radar pole. It was on the boat when I bought it 16 years ago. The original owner installed it 27 years ago. I can't compare it to other mount options because it is the only one I've ever had. What I can tell you is that it has been flawless in that time.


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Old 26-03-2016, 22:31   #3
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Re: Best mount for a Radar?

If I remember correctly the formula for radar horizon is 1.23 square root of scanner height.

So For me, it is all about positioning antenna the highest safe place away from humans and with a minimum of interference to other sensors

Your mast is structurally the strongest, so why put anywhere else?

Also the primary radar function is about detection and tracking at ranges between 6 to 12 mm.....not using it for avoidance at 50 meters.
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Old 26-03-2016, 22:53   #4
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Re: Best mount for a Radar?

With the 3G on the mast you will see objects very close to you. The vertical spec on the 3G/4G is 25 degrees. Don't over analyze it. The mast will work fine, and your boat can certainly handle the 20 lbs.
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Old 27-03-2016, 09:51   #5
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Re: Best mount for a Radar?

Quote:
Originally Posted by Pelagic View Post
If I remember correctly the formula for radar horizon is 1.23 square root of scanner height.

So For me, it is all about positioning antenna the highest safe place away from humans and with a minimum of interference to other sensors

Your mast is structurally the strongest, so why put anywhere else?

Also the primary radar function is about detection and tracking at ranges between 6 to 12 mm.....not using it for avoidance at 50 meters.
When the new "digital" radars came in a few years ago, I asked a radar technician/installer what the best choice was.

Sensibly, he asked me "where will you be sailing?"

I replied that we hoped to do a circ with long ocean passages alternating with lagoons in places less visited.

He said "get both. The older pulse type for distance, seeing weather and being seen, and the newer digital type for fine resolution when the ranges are short, like mooring fields at 0300h and counting dock ends in unfamiliar marinas".

I thought it encapsulated the strengths of both radar types. If you are indeed a coastal, short-haul sailor, the newer types are great because they excel over the short range, can be output to plotters for radar overlay, and are parsimonous on power draws. The "traditional" radars are great at distances (depending on radome height, of course) and can be fiddled with to reveal weather, which can be avoided. I've done this on delivery: thanks to radar guidance from the skipper, I've steered between thunderheads and downpours to avoid local downdrafts and, of course, a good drenching.

His comments also illustrated that the best way to buy a radar is to learn more about how to work it, and to let that knowledge guide you.
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Old 27-03-2016, 09:56   #6
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Re: Best mount for a Radar?

Mine is on a pole, but that pole also contains other things that weren't going on the mast.

But I believe the 4g RADAR way out ranges the 3G, might want to see if I'm correct or not.



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Old 27-03-2016, 10:36   #7
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Re: Best mount for a Radar?

After using our radar on a fixed mount, and then on a Questus swivel mount.....put it on a swivel mount no matter where you decide to put it! If you're sailing flat, it's not an issue. but heel the boat over at 15-20 degrees, and your pic will change dramatically. If you ever want to avoid freighters, or thunderstorms, or whatever when you're sailing, put it on a swivel! FWIW, ours is on the mast, and after 16 years of owning/using this radar, I've never had to do any mx on it. Mounting it low down for mx ease is a non-issue, in my book.
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Old 27-03-2016, 11:12   #8
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Re: Best mount for a Radar?

I've had the same Questus mount on two boats over 20+years. Because mine includes a lower section to accommodate a hydraulic back stay cylinder, it was damaged when the hydraulic cylinder failed and the back stay went slack, while flailing the radar dome. Result: bottom section was torqued into oblivion. Once ashore, I replaced the lower section with a fabricated stainless section. The Questus mount works fine. Self-leveling feature is invaluable for a sailboat. I'm Not sure if Questus still makes an add-on that allows additional antennas , etc., but you can always have something similar fabricated.
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Old 27-03-2016, 13:42   #9
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Re: Best mount for a Radar?

Hi.
Why not install lower on the mast at abut 2.5-3 meter, and additional deck light under the radar?
Ilan
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Old 27-03-2016, 13:58   #10
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Re: Best mount for a Radar?

Quote:
Originally Posted by Pelagic View Post
......
Also the primary radar function is about detection and tracking at ranges between 6 to 12 mm.....not using it for avoidance at 50 meters.
That's not how I use our radar. For us it is used in 4 ways. Long distance to look at squalls. In this case, radar height is not important. Close in maneuvering in reduced visibility and at night. In this case, lower mounted radar is probably better. As a guard zone set at around 2 miles for offshore when conditions suggest it, and finally to use the MARPA capability to determine the course of vessels in the 1 to 6 miles range that do not have AIS.

None of these require the Radar to be mounted high on the mast.
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Old 27-03-2016, 15:03   #11
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Re: Best mount for a Radar?

That is an interesting assessment Paul especially the transition to depending on AIS for early detection which helps with vessels but not so much approaching reefs in poorly charted areas

My own Radome is about 18 to 20 ft above the pilothouse, which I do not consider high.
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Old 27-03-2016, 15:36   #12
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Re: Best mount for a Radar?

Call the manufacturer ref mounting height, you may be surprised as I was with their answer.
I think maybe once I was in fog that you really couldn't see 30 ft, my only use for Radar at that point was to watch for the idiots that were still trying to make way


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Old 27-03-2016, 15:44   #13
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Re: Best mount for a Radar?

Thank you all for your good comments!

Here are my conclusions: I think I won't mount it on the back stay due to the extra strain I would put on it. I don't like neither the mount on the mast, because of the extra weight and the problems with the large genoa, as I have.
It is true that the formula to calculate the horizon for a radar is 1,23 x square-root(h), so if we use that we will find out that the difference between the horizon of a radar mounted on a 3 mt pole (2.1 nautical miles) with the one of a radar mounted at 9 mt (3.7 nautical miles) is to my opinion very small. I agree with Paul about the main needs and usage of a radar. Specifically regarding the squalls detection, if we use the above formula, you will find out that the difference between a mast and pole mounted radar is really small. However the lower mounted radar will give better visibility to shorter range targets.
As far as the difference between the 3G and the 4G radar antenna, according to Simrad, the 4G is a higher performance antenna, it has dual operating speeds (24RPM and 48RPM) and a longer range of about 2NM, the 4G is really perfect for high speed boats that require faster refresh rate and that extra range, one benefit the 4G has over the 3G that is nice what ever boat you have is the beam sharpening function that just sharpens up the edges of the target for a clearer picture on your display.

With all the above said, I think that probably the best mount would be on a pole (about 3 mt high)with a self leveling thing. The pole should be mounted on the starboard side in order to have full visibility about the boats that have right of way. The same pole will be used also to install more (future) equipment and antennas.

Buon vento
Paolo


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Old 27-03-2016, 16:16   #14
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Best mount for a Radar?

I've had my radar mast mounted except when I went to Florida and returned a couple of years ago, transiting 650 miles each way on the Tennessee River and Tenn-Tom waterway. I've sailed on several boats in SW Florida all with mast mounted radar. While on the rivers, I had my mast down and did a temporary mount on the front portion of my mast cradle. Fog is a concern both ways on the river and I spent many hours in partial and full fog and also ran at night a lot.

Paul made some very pertinent comments about how radar is actually used and I agree with all of them. My radar is a 2KW 2003 Raymarine color Pathfinder but I can see within a half boat length of my boat with it on the mast. I'm about to replace my KVH pole mounted TV antenna and I am now thinking I'll get a mount for the top of my pole that will let me pole mount the radar and put the KVH antenna on top. That will keep me from having to do a temporary mount when I take my next trip to Florida. I use my radar on Kentucky Lake for tracking tows on Marpha (now also have AIS for this) and for traveling at night and in fog. Same functions work on the Tenn-Tom. I also use it to track weather systems on MARPHA and I think the pole will be just as good for that. I use the radar, along with AIS, while offshore to spot potential conflicting traffic. Paul is right about offshore range. I typically have the Chartplotter with radar overlay set on 12 miles, 6 if close to traffic, so 1-6 mile conflict range is enough for most
collision avoidance strings (along with AIS for the big boys who go 20 knots) Radar is still necessary as many people like me only have a receive only AIS. I've come 180 degrees since I first installed radar in 2003 and now I think the pole is the way to go. My next question is what is the best radar now. I spent a couple of hours yesterday trying to sort out digital, HD, etc and still don't know what is best.


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Old 27-03-2016, 16:28   #15
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Best mount for a Radar?

Mine is pole mounted on a Kato combo pole, the KVH TV5 is above the RADAR.
As far as which is better, I don't think it's as clear cut as that, my old Garmin 18HD was awful good, on par with my 4G, in my opinion.
For fishing the holy grail is finding birds, and while many claim that capability, I have yet to see one that does, but I have been out of the fishing thing for awhile now. Point I guess is reality and what is claimed often differ

My belief is buy the plotter you want that can use the mapping charts you prefer as most likely you'll be buying a combo unit anyway. I believe the RADARs are close enough with some having a little edge in one thing, and others in another, they are all good.
But if your stuck with charts you don't like, well I couldn't live with that. What came in my Zeus, was terrible, thankfully it will accept others.


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