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Old 06-01-2011, 20:17   #1
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Broadband / FM Radar . . . First Impression: Wow !

Over a year after buying it (this old house syndrome*) we installed the Simrad Broadband radar last weekend while on a mooring, during our x-mas and new years "cruise".

We only got to use it for the 25 NM crossing back to the mainland, but it was sweet ! We powered all the way so we don't know how it does when at a heel but we got a good solid echo from landmasses over 25 NM away. Given the super low power usage I'm amazed we saw anything beyond 10-15 NM.

The resolution was amazing and the harbor scale resolution was almost good enough to navigate us back into our slip with zero visibility, literally.

So our first impression is a solid "WOW !".


* This Old House Syndrome: Plan to replace a faucet and end up having to rebuild the garage and second floor due to structural or mechanical interconnections.



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Old 07-01-2011, 07:13   #2
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Sven--Cruising magazine had an article on these units a while ago that seemed to indicate the performance/resolution at longer ranges 6-12 miles was poor compared to units such as the old Raytheon R20XX. What was your experience (detecting a land-mass at 20 miles+ really isn't to indicative. A ship running at 17 knots at 12 miles would be another matter.)
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Old 07-01-2011, 08:02   #3
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It has been my experience installing a few, and I repeat, a few, of the broadband units that the long range performance has not been up to the same standards as our old radars and the older units have actually created interference with the broadband. Most owners have not reported significant improvement in detecting targets close in and if a target gets too close it can be lost altogether depending on the mounting placement of the array. There are also some issues with tracking rain and particularly rain squalls and that is a very important feature for us in having a radar unit on board. We don't have a broadband unit installed on our boat yet so these are reports from other owners. So far, I have resisted the temptation until there is a little more reporting from first hand users. Chuck
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Old 07-01-2011, 10:34   #4
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Originally Posted by svHyLyte View Post
Sven--Cruising magazine had an article on these units a while ago that seemed to indicate the performance/resolution at longer ranges 6-12 miles was poor compared to units such as the old Raytheon R20XX. What was your experience (detecting a land-mass at 20 miles+ really isn't to indicative. A ship running at 17 knots at 12 miles would be another matter.)
I would expect that longer distance detection would be poor in comparison. I hadn't expected to see even a big landmass at the distance we did based on what I'd read. Another drawback is that the low signal strength is too low to trigger automatically responding radar devices.

We didn't see any container ships under way but there were four ships of some kind on a roughly parallel course coming into Long Beach via the southern shipping lanes, 10+ miles away. They were not container ships. They showed up all along even though I couldn't see which ones they were. The visual background was a bit confusing.

Pleasure boats showed up as smaller targets that would pop in and out as we rolled a bit in the swells. Radar reflectors seemed to pop up like big blobs, at least I think that is why some of the targets showed up so big.

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Originally Posted by Waterwayguy View Post
It has been my experience installing a few, and I repeat, a few, of the broadband units that the long range performance has not been up to the same standards as our old radars and the older units have actually created interference with the broadband. Most owners have not reported significant improvement in detecting targets close in and if a target gets too close it can be lost altogether depending on the mounting placement of the array. There are also some issues with tracking rain and particularly rain squalls and that is a very important feature for us in having a radar unit on board. We don't have a broadband unit installed on our boat yet so these are reports from other owners. So far, I have resisted the temptation until there is a little more reporting from first hand users. Chuck
Don't know about rain detection so I can't comment on it. You are probably right.

The overall resolution and the close in resolution was what surprised me the most, it was as good as the print ads show. We could pretty much pick out every boat as we came back through the marina and when we were back in the slip we could see the neighboring boats ~20 feet from us, and the ones beyond. Many of the targets would bleed together on the screen but we could have drawn a pretty accurate map of the dock layouts for all the fingers in the marina that weren't shaded behind land or building masses.

I had the unit set for automatic condition detection (harbor, open ocean etc.).

We do not yet have a heading detector so every now and the the chart plotter overlay would get misaligned because our COG as determined by the GPS, and the actual heading were not the same. We are getting a heading detector with the autopilot and I think it will talk to the radar-chartplotter too.

We did have one stretch in the harbor where there were obvious false reflections behind us. They were so obvious that even if we were in fog we would not have been confused by them. They may have been due to interference as you mention as we were in the vicinity of some huge operating tugs at the time.

Our installation is a rigid mount about 20-25' up the mast.

I have only used radar on OPBs before so take my enthusiasm with a grain of salt. We picked the unit because of the low power consumption but the resolution is a wonderful added bonus.


-Sven
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Old 07-01-2011, 14:49   #5
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G'Day Sven,

So, have you actually measured the power consumption, as installed and in real use?

I'd be glad to find it out... don't at all trust the OEM's claims!

Cheers,

Jim
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Old 07-01-2011, 18:44   #6
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Sven--Thanks for your notes. By-the-bye--just where are you in Long Beach? We were members of ABYC so for many years before we decamped for Florida and warmer climes our slip was in the basin righ next to the Club and we do remember those times fondly.

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Old 07-01-2011, 19:05   #7
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G'Day Sven,

So, have you actually measured the power consumption, as installed and in real use?

I'd be glad to find it out... don't at all trust the OEM's claims!

Cheers,

Jim
Not yet. I'm not sure how I would do it either as the chartplotter draw factors into the use as well. However, the fact that there is no warm-up does mean that it (the radar) could be left off and only turned back on every 15 minutes or so for a watchstander survey of the surroundings ... it might be a useful feature to have that done automatically ?

Since the only part that wears out (no magnetron to burn out) is the belt drive I think the belt is the only back-up spare we'd need to bring. Just need to get the belt and a shop manual that describes how to replace it 25 feet up the mast in pouring rain and big swells

Quote:
Originally Posted by svHyLyte View Post
Sven--Thanks for your notes. By-the-bye--just where are you in Long Beach? We were members of ABYC so for many years before we decamped for Florida and warmer climes our slip was in the basin righ next to the Club and we do remember those times fondly.

svHyLyte
We're up in Cabrillo Marina, next to San Pedro. It is the nicest US marina we've been in so far. Hurricane Gulch is a bit of a challenge at the end of weekend cruises as we'll ghost across the crossing only to have the wind pick up as we get closer to the breakwater. Once we get inside the breakwater we'll often have 20-30 knot winds on the nose as Hurricane Gulch lives up to its name !

It is a very nice place to be until we cut the shore-cord and head out for a several years.


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Old 17-02-2011, 21:13   #8
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I'm still very happy with it

We have seen the interference from high power radars in proximity (2 NM ?) messing up the display so that is definitely something to be aware of. Other than that issue we have no problems to report after a few "interesting" shipping lane crossings during the past month or two.

YMMV, of course.



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Old 08-03-2011, 21:58   #9
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Re: Broadband / FM Radar . . . First Impression: Wow !

Gut check requested.

Am about to pull trigger on Lowrance BR24 and Lowrance HDS-8M to compliment my Vesper Marine Watchmate 850 AIS-B transponder.

Application is 1) collision avoidance, and 2) local weather identification on power-limited sailboat with mostly coastal cruising and some bluewater.

Reasoning follows:

Rapid "on" allows conservative power management.

Collision avoidance is most important in congested areas, especially unfamiliar waters, where the superior close-in resolution of the "broadband" excels. In open sea, the AIS transponder will aide in collision avoidance since most vessels there are commercial - especially the rapid ones. The AIS will make up for the BR24's reduced clarity at long range.

The restricted range of the BR24 in heavy rain is offset by a) the AIS in open water and, b) standing orders to delay non-emergency entries to unfamiliar ports during extreme weather. In an emergency, the GPS and charts coupled with AIS and high resolution near-field BR24 radar will be used to minimize collision risk.

In my limited experience, radar is used in relation to local weather in order to maximize speed by optimizing canvass and/or direction changes during a race. For cruising, the standing orders will be to reef when in doubt, thus rendering the weather radar function secondary (I understand that the broadband will show weather systems, just not as well as the pulsed competitors).

Please confirm my understanding that the height of the antenna (despite the reduced health risks of the BR24's low energy beams impinging on crew's heads) needs to be as high as practicable to maximize range.

Also, please confirm my understanding that any radar needs a gimbaled mount on a heeled sailboat (even the BR24 with it's rather wide beam geometry).

Lastly, would appreciate comments on the quality/accuracy/availability of international e-charts for the Lowrance multi-function displays. Do they compare favorably with others?
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Old 08-03-2011, 22:18   #10
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Re: Broadband / FM Radar . . . First Impression: Wow !

Concerning the "high as practicable to maximize range" I have heard the argument that it needs to be lower for closer in views. I do not yet have radar, but I am seriously considering it this year.
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Old 08-03-2011, 23:02   #11
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Re: Broadband / FM Radar . . . First Impression: Wow !

JD,
for me the no 1 reason for having radar is to plot accurate position fixes as backup and check on GPS, 2 collision avoidance, 3 weather spotting.

Would be intrested in the broadband performance in 20-24-32 mile range.
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Old 09-03-2011, 07:38   #12
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Re: Broadband / FM Radar . . . First Impression: Wow !

[QUOTE=JDGreenlee;638308]Gut check requested.

Am about to pull trigger on Lowrance BR24 and Lowrance HDS-8M to compliment my Vesper Marine Watchmate 850 AIS-B transponder.

Nice set up. I like the Vesper designs. Not the price, but it seems pretty clever and gives the Class B functions a lot of people want ("to be seen").

Application is 1) collision avoidance, and 2) local weather identification on power-limited sailboat with mostly coastal cruising and some bluewater.

Reasoning follows:

Rapid "on" allows conservative power management.

Collision avoidance is most important in congested areas, especially unfamiliar waters, where the superior close-in resolution of the "broadband" excels. In open sea, the AIS transponder will aide in collision avoidance since most vessels there are commercial - especially the rapid ones. The AIS will make up for the BR24's reduced clarity at long range.

I haven't used the new BR24 or its similar cousins under other makes, but I certainly have read a great deal about them, as they interest me for many of the same reasons. I question the notion of "reduced clarity at range"...my impression is just that they are very good close in, and merely average for a 2KW equivalent cathodic-style RADAR at 20 miles or more.

Frankly, that doesn't matter to me. If it can see a 60 knot wave front four miles high, that'll do, because I don't care if there's a 22 knot ship coming at me that's still 20 miles away as I would have under 20 minutes to reef down for what I can see, and 50 minutes to change course for what I have yet to see. A non-issue in my mind.


The restricted range of the BR24 in heavy rain is offset by a) the AIS in open water and, b) standing orders to delay non-emergency entries to unfamiliar ports during extreme weather. In an emergency, the GPS and charts coupled with AIS and high resolution near-field BR24 radar will be used to minimize collision risk.

Sounds reasonable even if you had a gigantic radar. A PSC 37 is a fine cruiser, but crap weather can push you into a breakwall no matter how well you can see it. I have no conclusive information on how the BR24 operates in heavy rain, but again, if it's that heavy, heaving to is prudent when there are doubts about the area, the chart freshness and the local traffic. All the unlit fishing boats coming home at once into a tight harbour in nighttime heavy rain would keep me out even if I could see them all.

In my limited experience, radar is used in relation to local weather in order to maximize speed by optimizing canvass and/or direction changes during a race. For cruising, the standing orders will be to reef when in doubt, thus rendering the weather radar function secondary (I understand that the broadband will show weather systems, just not as well as the pulsed competitors).

Again, I'm not sure if the deficit is so marked. Cruisers use radar to see rain columns or squall lines, sometimes to avoid them, sometimes to clean the decks of salt. I don't know if "showing as well as" comes into play, because with the right tweaking and mucking with the gain, they are a) very visible and b) give returns unlike solid objects. So I don't see how it would be different for BR if you played with the controls and learned its little ways.

Please confirm my understanding that the height of the antenna (despite the reduced health risks of the BR24's low energy beams impinging on crew's heads) needs to be as high as practicable to maximize range.

Yes. The "antenna" of a enclosed, circular sort of array in RADAR is typically called a 'radome" to distinguish it from radio.

However, as has been pointed out, the higher you go, the less the beam can reach close in. Having established that you value the short-range resolution of the BR type, why would you sacrifice that for maximum range?

The usual compromise is to mount it at the (first) spreaders, 20 feet or so off the deck. This means you get a nice "height of eye" that preserves returns up to the last couple of hundred feet or so around the boat. You can measure this precisely, of course, by approaching a small nav buoy in calm seas on a direct line and seeing when it vanishes off the screen. Measure that and you can figure out how close you are to all sorts of things.


Also, please confirm my understanding that any radar needs a gimbaled mount on a heeled sailboat (even the BR24 with it's rather wide beam geometry).

This is generally considered a good idea, if not a strictly necessary one. Gimballed mounts on mast fronts are nice for freeing or chafing less fully deployed furling genoas, because they "give" a bit. Again, if you are looking to get the most from the short-range resolution, a gimbal will make for a more persisting "shot" as you approach a harbour because the angle will be more constant.


Lastly, would appreciate comments on the quality/accuracy/availability of international e-charts for the Lowrance multi-function displays. Do they compare favorably with others?

No comment here. Lowrance makes nice stuff, but they seem to have a smaller marketing budget than their competition. Consequently, I hear little about their charts.
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Old 09-03-2011, 09:19   #13
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Re: Broadband / FM Radar . . . First Impression: Wow !

To repeat what I posted above. My only negative observation so far is the interference from high power radars in the vicinity. In congested areas that could actually be a problem if everyone is running around with high power radar beams all over the place.

I don't know if such interference is an issue with standard radars ?

I also don't know if there is a way to reduce the interference ?

We love ours !



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