JRC Radar - thoughts?

[Guest]

Spring is in the air, so we went to the boat yesterday, and it's put me in the mind for buying toys. I have very limited room for electronics at the helm, so Iam looking at a small radar/plotter. Swa the JRC Radar 1800 at LBS, and it looked interesting. Anyone got any experiences of small LCD radars?

Also, I understand I will need a high speed fluxgate compass. Never seen 'em listed. Where do I find one?

TIA

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[longjohnsilver]

I have a Furuno LCD radar, replaced a knackered CRT Decca which I rated highly.

Didn't think the lcd would match the clarity of the CRT but I was wrong, it really is superb, would recommend it to anyone. Looked at JRC which have received some excellent reports, but plumped for Furuno cos the local chap provides good service

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[jfm]

forget the compass?

You might get away without the fluxgate compass. Presumably only needed so you can set the display to North Up. But imho North Up is a waste of time. The only thing useful on a radar is Course Up, as it is an anti collision device and you want to see the targets ahead of you or fine off the bow, on the screen. All imho but might save you £££.

Also not having the compass might prevent the radar from showing your target waypoint on the radar screen, but that's no big deal imho....

 

[byron]

Re: forget the compass?

<font color=blue>I agree, I mean, I can see why a Warship would need North up but in my opinion we Yotties only need Course up.


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[miket]

Funnily enough was talking to a knowledgable fellow on Saturday night who had few good things to say about the JRC LCD radar that he had. Don't know which model, but 30 ft boat, so probably smallish.

I also had a Furuno LCD radar on my last boat, which proved to be extremely effective, picking up 20 ft French day fishing boats off the Cherbourg peninsular in half mile visibility particularly well. None had radar reflectors.

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[DavidJ]

You only need a flux gate compass if you want to overlay radar on a course up chart. A neat thing to do but worth the expense??
I refer to the Raymarine product for overlay I assume the JRC does the same, hence your question. Incidently a year ago when I looked into this Raymarine didn't have a fast enough flux gate compass and use some other manufacturers product.
David

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[jfm]

not a fan of overlay

It's just my £0.02 worth but having tried overlay on the latest Furuno kit (tcm's boat) it is a total waste of time imho. If you set the chartplotter North Up (as I do, and I think most people do) the elctronics seem to draw the radar on top of the chart. As the heading of the boat moves slightly, a couple of degrees either way, the radar becomes not properly lined up with the chart, so the computer then redraws it. If the boat is moving, this happens every few seconds, so the radar is nearly always redrawing. Thus you get cluttered, useless screen imho.

Much better to have N Up chartplotter, and Course up radar to spot collisions, on separate screens, imho. Praps different on warship as Byron says?

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[Guest]

Re: been \'sold\' to

Thanbks for the input, folks. Man at the boat show pointed out that if it got it's heading info from the GPS, it wouldn't know what to to when moored/anchored (true). It only just dawned on me that the bloody thing will always be able to display 'pointy end up', won't it? Doh!

The JRC Radar 1800 won't do overlay, but willshow radar and chart one above the other on a split screen, so although it may be nice to have them both on North up, it's not essential.

As an aside, for those with radar, how often do you use it?

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[Renegade_Master]

Thought fluxgate to do with autopilot . Surely radar onto chart plotter (managed by gps) is via NMEA connection or am I missing something

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[byron]

Re: been \'sold\' to

<font color=blue>Personally Graham, at sea mine is never off. I might well forget to switch my GPS on in fact I often do forget because I can always work out roughly where I am anyway and don't really need it for popping across the channel and sea passages I am familiar with i.e. London - Ramsgate. My Radar however.... I just feel comforted by it even on the nicest of bright sunny dead flat calm days.

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[martinwoolwich]

North Up

I was told that in bad weather the best way of setting an EBL for collision avoidance was with the radar set to North Up. This would ensure that the variation in the movement of my boat would give the wrong impression on the EBL and because NU is constant the EBL data would be much more accurate and therefore indicate possible collision more quickly. Is there anything to this thinking?

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[ArthurWood]

Graham - I have JRC1000 on my boat and although I've never had to use it in anger, it's very easy to use. I understand that the 1500 has better res. and is wort the bit extra cost. Don't know nuffink about the 1800. There was a review in MBY some years back which rated JRC1000 best buy

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[[2574]]

I disagree re the comments about North up being not relevant. I was trained by a guy called Robert Avis to use Radar, and admittedly he is a Navy guy, both on my own boat and using the Navy's simulators. I only use the Radar in North up, the main reason being that it is so easy to reference from the paper chart to the radar screen as they are both North up. It gives great confidence in interpreting the radar picture. I also have the overlay facility on my furuno radar/plotter and think it's just superb because it gives such good assurance as to GPS's accuracy. Remember that GPS is only "where you're supposed to be" whereas radar "is where you damn well are" and if the two agree you have a high assurance factor. I don't have the redraw problems that were mentioned earlier, I suspect this problem is being caused by the fluxgate compass not being fast enough. There is a hugely expensive fast furuno fluxgate for this purpose, but I have linked in to the raytheon fluxgate used by the autopilot to give me a heading sensor and it works fine.

My advice is too perservere with North up, when you first have a go it seems a nonsense compared to head up, but head up really only gives you collision information whereas in North up the radar becomes both a navigator and collision avoidance tool - ever done any parallel indexing? Go on a Robert Avis training course............

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[Guest]

No, normal radar display is course up, i.e. the top of the display represents the direction you're pointing. Standard for a chart plotter is North up, which is obvious. If you want the two to be the same way round, you need some way to tell the chart display which way you're headed, or the radar which way is north.

A GPS only updates position once a second, and from that the plotter or radar can work out which way you're headed (based on where you are and where you were a second ago). So the heading data is a bit innacurate (well, it might be OK on a rag'n'stick boat, I suppose).

The only way to get the chart and the radar to both point the same way reliably at speed is a high speed compass. But I now realise that you would really only need to overlay or synchronise like this to try and match up features - e.g. in fog, is that a boat at anchor or a buoy. Not that it matters, you just avoid running into it in either case.

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[byron]

Re: North Up

<font color=blue>Everything is a matter of taste Martin. I prefer continual head up then at any time I know where I stand, no chance of accidentally working to the wrong data that way. I confess I use mine solely not to bump into things and to a lesser extent for navigation or an even lesser extent into a foggy harbour at night. I really do not use Radar to its fullest ability.

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[tcm]

Re: cheap lcd radar fan

i had a dirt cheap a'helm 500 (?) and you definitely see everything no problems when you really really need to do so. The radar salesman says ah but u can't see the screen in sunlight but of course, if sunny, don't need radar. Like coins that are spun before a game, matches, biros and envelopes, the cheapest option does the job pretty much as well as any other.

Best is to make sure you try the radar nearly every single time you so out, so you are sure that you are seeing everyting and that u know what a boat 1/4 mile away @ 45 degrees looks like in real life.

The twirly radar things are better imho so you can see if it's buggered or not, but not too serious point really.

I agree with jfm that superimposing radar on chartplotter is mainly so visiting gizmo nutters (esp thos who recommend/suggest massive spec kit AHEM) are amply occupied and amused en route. teh redrawing is only when it starts up i think(?) cos it was okay when offshore in antivbes with ljs and sjs from italy, coming at night at 25 knots ooer with everything on the radar full brightness aargh without any redrawing.

However, I admit that I have upgraded my own radar kit with decent amplifier and mega helm audio speakers for coming season so that the DVD-playing on the radar screen is much improved, without having to rely solely on the radar arch speakers .

 

[DavidJ]

I think it's all a question of speed. The GPS does not react quickly enough to give an accurate overlay ie orientation of chart course direction to radar straight ahead direction. From jfm's interesting actual experience, a high speed compass although hundreds of times faster still doesn't seem to do the job very well either.
David

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[tcm]

Re: not a fan of overlay

oh right ta very much. One minute you recommend some top kit, but this year it's a pile of old shite. The tv/dvd option is very good though. the redrawing was only to get started. Also the fluxgate doodah is set wrong, i think. Anyway, i'm a bit bored with fiddling with submenus now so how about a nice beer?



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[DavidJ]

Re: North Up

I think of radar as my eyes in the fog and when I look straight ahead I want to see the same orientation on my radar. No interpretation required forward is forward which has got to be the safest most foolproof way of navigating in fog.
David

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[byron]

Funnily enough was talking to a knowledgable fellow on Saturday night .
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I saw you Saturday night, you could hardly stand up let alone hold an intelligent conversation. You were dancing like a Dervish and trying to 'moon' Mark Warner's guests.
In fact your behaviour was appalling and as I sat under my table waving my underpants at you I thought to myself "I'm glad I am too tiddly to sit on a chair and not making a fool of myself like Mike is"

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