radar in the cockpit

[salamicollie]

There has been some research done for the MCA (I think) a while back on big ships and the conclusion was not to integrate with ARPA/Radar with AIS as the data wouldn't match - basically it was very difficult to correlate accurately. Hence AIS is a seperate box or poss combined with Chart plotters on many ships.

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[Robin]

My views are coloured a little perhaps by sailing short handed, but:-

1) Radar is not what you see at one instant but what you see evolving. An occasional glance just gives a still picture, you need to watch the movie.

2) We do not have MARPA, I would like it but I'm not sure I would trust it fully with small boat yawing/electronic compass stability etc. We do have 'trail' or 'plot' functions, good enough 90% of the time to determine hit or miss, the other 10% requires more study and use of EBLs/range rings or even a proper paper plot (we have a wipe clean radar plotting board from Davies USA for this).

3) Beause of 1) & 2) I believe that plotting properly can only be done at the Nav table, with no distractions.

4) Our radar is at the chart table, next to a 10" C-Map plotter. We have a 2nd autopilot control also at the chart table so the course can be tweaked from there and the results monitored. We have a 2nd and independent chart plotter on deck but not a radar repeater.

5) We can see our radar from the front of the cockpit well enough for less serious use, ie to decide if a trip below is required to check better.

6) Where do you mount cockpit radar? If at the wheel (most usual) it means you have to be at the wheel. I employ an autopilot so I don't have to stand at the wheel, so I wouldn't be able to see it from my usual perch. If it is at the wheel then it means the skilled radar operator will have to be there, not just the duty helm, there isn't room for both so now, if without a pilot especially, the radar bod will also have to be the wheel bod and you cannot concentrate IMO on both jobs at once.

7) If in the cockpit, everyone there then becomes an immediate (and distracting) expert, watching the screen instead of keeping a lookout even if at night they have any night vision left after staring at the screen.

8) My comments are from a yacht viewpoint where boatspeed is low compared to the ship's speed perhaps being plotted say 6-7kts us versus 12-25kts ship speed. I believe that may make us more affected by errors in bearing/distance than if we were at a similar ship speed as might be a mobo so more accurate plotting is called for. Hence cockpit radar on a mobo (especially on a flybridge) might be fine, I'm not qualified to argue that from personal experience.

9) There is still the problem of power consumption to consider. Our radar is 'off' unless needed. It will not go 'on' unless needed beause of visibilty under sail though I might switch it on under engine if the vis was good but it was at night or I wanted to play. One radar running below and a repeater outside and all the other electronic wizardry makes for a lot of battery drain, espeially at night with lights on as well, and we have Chernobyl-like power generation on board unlike many who might need the engine to keep up.

So there you have it, it is a personal choice but I haven't found reason to change my views even after many trips spent staring at a screen in bad vis,. I do suspect though if I had a fast mobo I might think differently, but I'm not quite old enough yet for that /forums/images/icons/smile.gif

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[erin_dawes]

We recently purchased radar which we put in cockpit but have wired up so that we can purchase another one at a later date to put near chart table. We did this because we couldn't decide where to put our radar and that seemed the best option at the time.

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[duncan]

Re: all fits together

as the 'fast' mobo owner the difference is clearly seen in the comment re sitting down below and even steering from the chart table!
even if I had an autopilot I couldn't consider leaving the helm at planning speed for a whole host of reasons - letting go of the wheel maybe...........just....../forums/images/icons/smile.gif

<hr width=100% size=1>madesco madidum ..../forums/images/icons/smile.gif

 

[Robin]

Re: all fits together

Thank god for that! We raggies do wonder who is in charge when we see a mobo coming at us, knowing especially that we erm sometimes desert our post for a minute or two.....

I took ours through the Chenal de Toulinget short cut going north through the rocks off Camaret 2 years ago in 20m vis and steered from the chart table by plotter, wpts and radar with SWMBO out in the damp up top. She asked when we would be through and I said we are already and should see Camaret anytime - she saw nothing despite passing the knobbly bits about 50m away.....



<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[flaming]

We have our radar in the cockpit. Since we normally sail longer overnight passages just 2 or 3 up it makes a lot of sense to be able to stay on deck and, as someone else said, watch the radar picture evolving. Having the radar visible from the helm also makes the task of piloting the boat into a harbour in poor visibility much easier as the helm can see the radar information himself.

As an aside, with an intergrated system such as ours, we are able to call up any data that the helm may want in small boxes on the radar screen. The hidden benefit of this comes when sailing with a large number of friends. Wheras the forward instruments (depth, speed etc) are obscured by bodies the radar right in front of the helm is not. This is especially handy when looking for a good spot to anchor.

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[Talbot]

navman 5500 plotter can be dimmed sequentially as it gets darker outside until it is not intrusive against night vision, but still good enough for use.

Some radars will reverse the colours so that the picture is predominantly black, with just the contacts painting white, again this helps to preserve night vision.

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[Jools_of_Top_Cat]

I understand that, but from my helm looking to the water in front of the boat even very dim instruments were hampering my view. Also I do not like the night setting on the radar, it just doesn't seem to work with LCD screens. MHO.

My plotter has but one light setting, as does the sounder, they are not glaring but still too bright. I am going to pull them apart this winter and fit red bulbs or paint over the white ones in the sounder.

The radar can stay white while it remains by the chart table.

<hr width=100% size=1>Julian

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[BlueSkyNick]

We've done much the same. The display is under the spray hood, so I can see it from the helm or if taking shelter in bad weather, with autohelm on.

SWMBO can sit and watch it sitting in her favourite position too - when not fast asleep in her pit.

We haven't got the cabling to the chart table though, but it would be very easy to install - just got to take the damned head linings down again !!

<hr width=100% size=1>It's frustrating when you know all the answers, but nobody bothers to ask you the questions.

 

[duncan]

bit drastic all that taking apart - how about some thin red film over the screen at night?
come to think about it seems a good product oportunity for someone - sheets of the stuff just like the screen protection stuff you peel off when they arrive in the box new but with a slight red tinge,

<hr width=100% size=1>madesco madidum ..../forums/images/icons/smile.gif

 

[Mirelle]

A bad idea, 95% of the time.

Radar is only of value if it is used properly, which means that the user has to concentrate on the display, and, in the case of collision avoidance, plot.

You will recall the MAIB report into the yacht which sank after collision with the containership in the channel; anyone thinking of fitting a radar should certainly read it.

A cockpit display is good if you are, eg, singlehanding into an estuary in fog, with the radar on a very low range setting.

That is about the limit of its safe use.

If the display is in the cockpit, the user is inevitably going to be distracted, which means that proper plotting is not going to happen. You need someone who has been taught basic radar plotting looking at the tube for minutes on end, just as in a ship's wheelhouse.

Absent this, you are safer without radar.




<hr width=100% size=1>Que scais-je?

 

[Robin]

Hear hear

Mirelle, I was beginning to distrust my own logic! However picture an entirely different scenario to yours and my use in a yottie context, and different yet again to big ship use, would you still think the same for a fast mobo? I might think differently if I had a flybridge thingy and go for dual station radar at the helm positions - but that would admit I might not slow down, just like the big b....rs don't! In all other cases inluding a mobo at displacement speeds I would say it HAS to be below.

Robin

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[duncan]

Re: Hear hear

can we agree upon it being in an area where chartwork/plotting can be done rather than necessarily below?/forums/images/icons/smile.gif (in my case that's too the left of the helm and the radar can be swiveled to be operated and observed from there when I have someone navigating, or of course slightly the other way when I am (effectively) single handed. The same would probably be applicable to many flybridge boats being helmed from the main station.

<hr width=100% size=1>madesco madidum ..../forums/images/icons/smile.gif

 

[Mirelle]

Yes, absolutely

I have nil zero zilch experience of fast flybridge mobos, but I confess that I admire those who do understand them, and who navigate them at 25 knots or more - not an easy thing to do.

I could not offer any constructive comment except to say that the large containerships that I manage, which also run at 25 knots, all have a bridge which looks rather like what you describe, except that the chartplotter-cum-radar is to the starboard side of the Officer of the Watch's comfy chair.

(Being somewhat Paleolithic, and inclined to shock junior officers by waving a sextant about, I still find it hard to get used to the idea of comfy chairs in the wheelhouse - the Ancient British used to ban all chairs from the wheelhouse for fear the OOW would fall asleep in them).

<hr width=100% size=1>Que scais-je?

 

[jimi]

Re: A bad idea, 95% of the time.

Most of the time a danger target can be identified fairly easily and an EBL placed on it, with the radar head up and a constant course & speed maintained it is then easily determined if what the cpa is and thus what your actions should be. Personally I'm keeping mine at the helm so I can see what is going on and eliminate the problem of (mis)communication between chart table and helm. However I am seriously considering upgrading to a Marpa system.

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[Solwaycruiser]

On my last boat the radar was normally mounted at the chart table. The cables had been kept long enough to reach out to a second mounting bracket which was made of stainless and mounted under the sprayhood. The cables sat coiled behind the radar display normally and when I put it outside two or three hooks strategically placed led the cable outside. It was only put outside a few times when I was caught in fog whilst singhanding but it seemed to me like a good and easy option(by a previous owner). It depends where the chart table is as to whether it would be feesable or not.

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[tome]

I haven't read the research, but it doesn't surprise me. Several reasons why it wouldn't easily correlate:

1 Poor bearing discrimination radar
2 Range discrimination an order worse than GPS positioning
3 Uncertainty as to AIS/GPS datum

However, I can see these problems being overcome with ARPA and continuous target tracking. I don't advocate combining AIS info with radar (screen clutter) but can envisage a situation where you could select an established ARPA target and call it via AIS box linked to DSC for direct bridge communications.


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[Oldhand]

Absolutely agree with all you say, an excellent "sermon" Robin.

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