8 Radar Use Tips

Wooden Fishing Vessels make very poor radar targets.
Wooden fishing vessels make very poor radar targets.

This is a first here at Attainable Adventure Cruising: Colin and John have teamed up on a chapter to share the fruits of some 70 years of combined radar experience, much of it in the foggiest (Atlantic Canada) and highest-traffic (English Channel) areas of the world.

[John's thoughts begin and end with square brackets like this sentence, so you can keep the two of us straight.]

Let's imagine that the fog has socked in good and proper. Radar comes into its own now, so:

Colin, European Correspondent here at AAC, is a deeply experienced offshore sailor who holds a Yachtmaster licence, and a gifted photographer and talented writer who has added a whole new dimension to Attainable Adventure Cruising. In addition, since Colin and Louise are from England and had their OVNI 435, Pèlerin built in France, they bring a European perspective to our site. You can read more about Colin and Louise and their business at their website.

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Marc Dacey

A very nice list, especially as it covers the less-obvious traps of not varying ranges, being “speckle-phobic” and the potential for confusing orientations and the need for training. While I’ve played with a few older sets, I have to learn how to get the best from ARPA and how to integrate AIS into a stand-alone RADAR’s output. Well done, you two.

Henrik Johnsen

Thank you very much for a informative post..!
I very much agree with you guys regarding the radar overlay function on MFD´s. In my opinion I would say it’s more or less useless.
But when it comes to using split screen mode on a MFD on the other hand, I disagree with you.
I find it very useful to have radar and chart on a split screen mode. This way it will just take a split second to compare the radar picture and the map. Especially when operating in tight corners or unclean waters I really appreciate NOT having to switch modes or fiddle around with different buttons. One wrong button pushed, which easily happens in heavy seas, and you have to move focus from navigating into handling your MFD, and thats the least you want to do in such circumstances.
On our Furuno NN3D plotter the cursor on one screen show as a (red) cross on the other when in split screen mode, a tool I find VERY helpful. If I see a blip on the radar which I don’t recognize, moving the cursor over it, the cross corresponding with the cursor shows immediately where this blip is on the map. The other way around, place the cursor on lets say a buoy on the map, and you will se where the blip on the radar should show up.
One thing one must take into considerations using MFD´s with split screen mode, I think it ideally shouldn´t be of no less size than 9-10“.

Colin Speedie

Hi Marc
What we wanted to do was exactly that – cover the simpler stuff that often gets overlooked. ARPA is great and I like having AIS of radar a lot, too.
I’m sure I can speak for John, too, and say we’re glad you found this useful. Thanks for saying so.
Best wishes
Colin

Colin Speedie

Hi Henrik
I’m not completely against split screen viewing, especially if it’s case of simple navigational use. My concern is when I’m trying to understand what a target is doing, especially if it looks like it might affect us. Then I want the least extraneous information possible, as I need to focus on the matter at hand. You’re quite right about ‘the fat finger syndrome’ by the way, when it’s all too easy to crash the system when you least need it. But I’m sure there’s an element of taste and liking what you’re used to, so I am completely open to the advantages of split screen use and I certainly agree that a decent sized screen is a must.
I haven’t seen the cursor cross that you mention, which sounds like a very good idea – I’ll find out more – thanks.
Best wishes
Colin

Neil McCubbin

The desirability of split-screen viewing depends partly on the size and quality of the monitor. We bought a top-line 22″ diagonalPC display when launching in 2004. It is rather outdated today, but is still larger than most yacht MFDs
We will probably replace with similar size better quality monitor soon.
We use split screen a lot. Agree wholeheartedly that weak targets show better on a plain black background (with a few speckles, as discussed above, of course)

Colin Speedie

Hi Neil
thanks for that, which bears out my own view that a decent sized screen is the only way to go if you want to view split screen effectively. When our MFD bites the dust this may well be the way we’ll go.
Best wishes
Colin

Marc Dacey

This is the plan for the pilothouse: a biggish monitor on an armature that can lie flat against the underside of the roof when not in use, but which can be brought in for serious nav work when every pixel needs to be seen. If it can be brought without arm’s length of one’s face, it needn’t be bigger than 19-22 inches, but that’s twice the size of most MFDs that aren’t five grand.

Richard Hudson

Thank you, gentlemen, for an excellent and informative post. I will print this article out and store it near the nav station.

Regarding #7, Orientation, and crew should generally not change settings such as Head-up/North-up and Gain: I have encouraged crew to change the Gain when making a large Range change, because the specks on the screen at 16 miles (my max Range) tend to disappear at 3 miles, which I think means the possibility of missing a nearby target, even though the gain was set correctly at 16 miles. Are you discouraging crew from changing the Gain as a way of simplifying their learning process, or because you do not find much of an improvement in target detection from adjusting the Gain after adjusting the Range?

Richard

John Harries

Hi Richard,

That’s a good point. I suspect this may be a set-specific issue, so with the behaviour you are seeing I think you are absolutely right to adjust. On our Furuno 1832 we have generally found that we can set a single gain adjustment that works well over the range.

Colin Speedie

Hi Richard, John
I think this is indeed set-specific. Some sets seem to tone down the gain as range increases, or else there’s some other form of loss that’s inherent in the system. Adjusting the gain is therefore sometimes obligatory.
Best wishes
Colin

Henning

In the entry above Colin linked to mvtanglewood.com. This site is written by Peter Hayden and certainly worth a read in my opinion. If you go there, also have a look at other entries.

Here he makes a case for relative motion vector feature and describes how it is often misunderstood or mixed up with “relative motion display” vs. “true motion display”:
http://www.mvtanglewood.com/2015/02/radar-comparison.html
Motion vectors are displayed only when using ARPA or MARPA so they have nothing to do with true or relative motion display. By default, the motion vectors are “true”, meaning they are drawn relative fixed features on land, for example. On some sets, the type of vector can be set to “true” or “relative”. If they are set to relative, then they become much more useful in passing situations as the vectors will then indicate if a target will pass you ahead or astern, and by how far, or if it will hit you. For example, if you have big fast target at a more or less steady bearing and closing, then a CPA value displayed will tell you how close you will get but only the relative motion vector will tell you if the target will pass ahead or astern. Knowing this can be crucial in some situations and will allow you to make a sensible course correction yourself if you would otherwise get too close for comfort.
Very few radars other than “fishermans radars” have this feature and in my experience, it is useless to ask a salesperson. In my attempts so far, I was unable to make them understand this feature so what they told me was nonsense. You will need to download the user manual and dig around in it.

The Simrad MARPA function appears to be fundamentally broken on all of their radars except the HALO open array radar.
Ben on Panbo has put up some screenshots of my 4G on this page:
http://www.panbo.com/images15/hennings-4G-marpa-screens.html
Which is linked to from this entry:
http://www.panbo.com/archives/2015/12/marpa_on_small_radars_is_navico_4g_especially_bad.html
Interestingly, Simrad offers relative motion vectors but as the entire MARPA feature is useless, so are the relative vectors (in my opinion).

In this entry Peter Hayden describes how the NMEA 0183 sentence “TTM” (Tracked Target Message) can be used to integrate a standalone radar, such as those offering the relative motion vectors, with a PC navigation software or even an MFD.
With Rose Point Coastal Explorer, an ARPA target tracked for example by a Furuno 1835 will give an icon and vector on the Coastal Explorer chart that is continuously updated.
The 1835 has a “TLL” button which makes it send a Target Latitude/Longitude NMEA0183 sentence once for each time the button is pressed, giving the L/L of the radar’s cursor position. However, this feature does not work with Coastal Explorer as CE doesn’t understand this sentence.

John Harries

Hi Henning,

Thanks again for that information on integrating the 1835 with a chart plotter. I will certainly experiment with that when we upgrade.

Rob Gill

Thanks guys, I really enjoyed your article – it set me thinking about our set-up.
On the ships I was on with commercial radar sets, we always plotted targets (3 or more “dots” over the target at set 3 or 6 minute intervals joined up on the screen itself), thus highlighting noteworthy targets and their tracks relative to us. Such visual plots were pretty essential when managing multiple targets at one time, such as when transiting the English Channel. Times two in rain or fog – there was too much chance for error trying to keep things in your head. And snap-shots from the radar didn’t tell you much, what was most important was the relative change over time – all too easy to confuse target movements especially when two or more targets were close to each other. At night, who can judge if you are seeing a bright light on a distant target or a faint light on the closer one?
A white chinagraph pencil, a short transparent and flexible graduated plotting rule and a repeating alarm that could be set to 3, 6 or 12 minute intervals were the tools of trade for plotting on screen relative tracks and closing speed. Using the rule and pencil to project the target’s relative track on screen quickly showed the CPA and provided an easy to measure distance to CPA. Then we estimated time to CPA using your “quick and dirty trick” and the distance scale on the screen with simple extrapolation along the track. Vector plots, usually in 3 or 6 minute intervals (12 mins at long range) for any dangerous looking targets quickly showed their actual course and speed.
Keeping the chinagraph pencils sharp so the plot didn’t hide any small targets, and pressing lightly to keep plots and tracks thin was important and doubly so on a smaller screen I would think. A simple arrow head illustrated relative closing or opening direction of the target track, and helped with identification and making collision avoidance decisions. Discipline in always removing old plots with a soft clean cloth as soon as they were clear was needed to avoid missing new, smaller targets.
In poor vis, I always liked having a target’s projected relative track line on the screen, which made any deviation to the plot pattern readily apparent, so indicating a change of speed or course. You had to be careful swapping between screens to return to the same plot scale – I always made a note in the bottom corner of the screen of my original plot screen range and kept plots on one screen at the same set intervals, usually 6 minutes as Colin mentioned – anything to make the maths under pressure easier and remove “errors of calculation” as our examiners deemed them.
I must confess, I have never used our 2 year old radar (coupled to a 12″ chart plotter screen) in ernest, as we almost never have fog here. Even our night passages have all been under clear skies so far, so your article has me thinking about testing it out – has anyone used on-screen plotting on the smaller displays we use on yachts?

You might then be wondering why we have radar at all? We probably wouldn’t for our sailing around NZ, but in areas of poor charting fairly commonplace in the Pacific Islands, it is a blessing – helps a bit for the odd tropical rain squall too. AND is in my view the biggest plus for overlay mode. With poor charts, overlay mode really helps correctly identify, then orient you relative to on screen hazards such as whole islands / reef structures etc, which can be out by as much as 0.5 NM on both your electronic and paper charts (though their positions relative to each other tend to be correct). Even old fashioned chart work is really hard with charts out by so much – oh and don’t expect buoys, beacons and lights to be where they were last time, or at all!
best regards,
Rob

John Harries

Hi Rob,

I did try on screen plotting years ago, but found it did not really work for me on the relatively small screen of our 1832. Instead, our standard practice is to go into course up as soon as we have a target, mark it with a VRM and EBL, and start the clock for three or six (alarm on my watch). The advantage of locking the radar with course up, rather than leaving it in heading up is that if we do need to change course we don’t lose our plot on the target.

Of course none of the above is a true radar plot, as we used to do on paper, but it does seem to be adequate in most situations, particularly these days when we are most often alerted to a course change by the target by the AIS.

On overlay, that’s a good point I hadn’t thought of. Might be very useful in the Arctic where datums are often off too. That said, I actually find it better to revert to paper plotting, assisted by ranges and bearings (mostly with radar), when the datums are way off as I find that no matter how hard I try the incorrect (in relation to hazards) position of the boat icon on a plotter confuses me.

Henrik Johnsen

Hi Colin
Regarding the “cursor – cross” issue I mentioned in my reply, have a look at this picture; http://www.panbo.com/assets_c/2009/10/-1172.html (copy from Hennings reply)
You find the cursor on the radar screen on the right hand side, and the red-cross on the buoy on the map at the left hand side screen.
Henrik

John Harries

Hi Henrik,

Thanks for the link. Sorry your comment got caught by our spam filter. That’s why it did not show. I just released it.

Henning

Rob:

you write about plotting targets “thus highlighting noteworthy targets and their tracks relative to us”. That’s a relative motion vector!
It’s actually the most basic feature of a good radar set. Probably all Furuno standalone radars have it and have always had it. So it’s frustrating that Furuno’s line of MFDs doesn’t have it. They offer “true” vectors, which sounds more advanced (and does take more calculation and data to produce) but it’s actually less useful in passing situations.
Simrad has it but the entire plotting feature (MARPA) is broken so it’s no help.
I don’t know about Raymarine and Garmin (as I said, my attempts to find out returned only useless information). Does one of the readers here know?

In my above comment I forgot the 2nd link to mvtanglewood. Here it is:
http://www.mvtanglewood.com/2016/02/integrating-radar-with-coastal-explorer.html

Colin Speedie

Hi Henning, Rob
what’s worth pointing out perhaps is that the Furuno stand-alone radars like the 1835 and upwards are the ones you are likely to see on small commercial craft like fishing vessels. And from my experience they have facilities (as you describe) and a standard of durability and reliability that reflects their intended use. One of the reasons I prefer them, and I think that’s true for John, too.
Best wishes
Colin

John Harries

Hi Henning,

That’s useful to know, thank you. Everything I’m hearing here is reinforcing my thinking that when we must finally replace our 18 year old Furuno 1832 our new unit will be an 1835. The other thing I like about Furuno is that they think about practicality when they design new units. For example the 1835 will fit in exactly the same mount as our old radar, both scanner and screen.

And yes, I agree, there is a lot of good stuff on Tanglewood’s site. That said he clearly has more money to spend on this stuff than most of us!

Henning

There is actually a new offering form Furuno one size down from the 1835, called 1815:
http://www.furuno.com/en/products/radar/MODEL1815
It’s only been released on this year’s “boot” fair 2 weeks ago. It’s certainly not a proven product but neither was the 1835 2 weeks after release. So I’ll keep watching it and wait for the user and installation manuals that I hope will be put up soon.
It uses the DRS4D 4kW magnetron scanner that used to be sold with NavNet 3D and even works with the MaxSea Timezero PC software alone. The DRS4D was tested well on Panbo many years ago but it is Ethernet-based. So the 1815 is, too. That’s a drawback but I have not read about reliability problems of this scanner with NN3D. I don’t know yet about relative motion vectors but I think there is reasonable hope. It will probably not support a dual-station installation as does the 1835. But it is way smaller than the 1835, much more so than the difference of 8.4” screen size vs 10.4” of the 1835 would make you think and it still has knobs. One to quickly switch the data display on the screen between off/some data/all data and the second one for gain/sea clutter/rain (press the knob to switch between the 3). There is a separate “Mode” button for HU/CU/NU and also a programmable function button that could be set up for trails on/off or as a TLL-button.
When I played with it at the boot fair, it all felt very solid and I am confident that I could operate it in the cockpit with one hand while holding on with the other.
It’s supposed to be very quick acquiring new targets to track but does not have the doppler radar functions of the DRS4D-NXT. On the Furuno booth it was mounted using a RAM mount for which the case works very well.
I will stop now lest you think I am a geekhead and send me back to Panbo 😉

John Harries

Hi Henning,

That’s good news. I took a look at the specs and I agree, a much better option than the old low end offerings from Furuno like the 1715, I think. Also good to see that Furuno is classifying it as suitable for small fishing boats, which indicates that they have confidence in its usability and reliability.

Henning

Peter Hayden (mvtanglewood.com) just alerted me to this post on setail.com about Simrad electronics including a Halo radar (latest technology 6ft open array):
http://www.setsail.com/simrad-marine-electronics-the-correct-choice-or-did-we-make-a-mistake-updated-3817/#more-43613

This sentence stands out for me:
“This is relatively common with smaller recreational units, but the MARPA values are unreliable- the recorded tracks of MARPA vessels would be safer.”
According to the information I got from Panbo, the Halo radar is the *only* radar in Simrad’s entire lineup that has received the “MARPA fix”. So I find it interesting that Setsail still complains about it.
In this entry Panbo’s Ben Ellison details Navico CEO Leif Ottosson’s grand scheme to conquer the world of marine electronics:
http://www.panbo.com/archives/2017/02/navico_hawks_2017_full_boat_integration_into_one_display_cluster.html
I have to wonder: Does Mr. Ottoson know that he is sitting on top of a huge pile of dysfunctional technology? Or is that even relevant to him?

John Harries

Hi Henning,

Yes, Steve and I chatted about his Simrad experience on the phone. Let’s just say that he was restrained in his writing. I may write more on this.

As to Pambo, I’m pretty disappointed with that site these days. A lot of breathless touting of new technology and not shred of critical review as far as I can see—I seem to remember that it was once better than that.

All of this makes me happier and happier about this recommendation: https://www.morganscloud.com/2016/01/28/marine-electronics-recommendations-radar/

Marc Dacey

John, I am trying to decide, in light of your recommendations, between the 1835 or the similar, but brand-new, 1815 (also a 4 KW model). I can’t even find a price I can rely on. Any thoughts? It has some very interesting features, but I can’t get solid info on it.

http://www.furuno.com/en/products/radar/MODEL1815

John Harries

Hi Marc,

I would go with the 1835. Larger screen and I know it works.

Henning

Marc,

while I have used neither radar, I wouldn’t call the 1835 and 1815 similar, primarily because the 1815 uses a 18” antenna (which will give 5.2° horizontal target separation) and the 1835 a 24” antenna (giving 4.0°) and because the antenna of the 1815 is connected via Ethernet.
Because of this and because the 1815 will not be a proven product for at least 12 months, I fully agree with John in that the 1835 is a much safer recommendation.
The 1835 will be significantly more expensive and use much more room and weigh more, both the display and the antenna. If this is critical for you, then you may decide to experiment, but you run a risk. An you will see reduced target separation due to the smaller antenna.
If you use the 1815 alone by itself and as shown on the system diagram, then the risk may be acceptable.
As it uses Ethernet and is the same antenna sold with Furuno’s MFDs and even the MaxSea Timezero Software, in theory you could combine the 1815 with these, building a system. The 1815 display in the cockpit and a PC at the nav station, for example. But I would never *recommend* to do this to anyone who doesn’t like fumbling with electronics like others like a Sudoku puzzle. Or who would mind taking a financial bath with it.

John Harries

Hi Henning,

Great analysis, thank you. I agree with all of it.

Marc Dacey

Thank you for your cogent analysis, Henning. Your points are well-taken. In fact, I’m concerned far more with the use of radar as a stand-alone resource with (at most) the ability to do a screen overlay of radar on PC for orientation, which I can do via NMEA 0183. I have no particular problem with the larger radome, and while I will have a small plotter at the outside helm, it will not need to display radar information. We have a steel boat and will have a Class B AIS transceiver: being “seen” by others won’t likely be a problem. We do, however, wish to see via radar and perhaps the 1835 is the proven product in that regard.

Marc Dacey

As an update to those interested, the 1815 radar now has a list price of $2,495 (U.S.) versus the 1835’s $4,495 (U.S.) and there’s a fresh Panbo review (if you put stock in such things) here: http://www.panbo.com/archives/2017/03/mibs_2017_furuno_standalone_1815_radar_dff-3d_multimodal_sonar_more.html

Of interest in terms of John’s “I know how it works” comment regarding the 1835 radar is the claim that the 1815 has the same “user interface”. Also notable (to me) are the feature of “true echo trails”, which have come up previously as a desirable attribute of a proper radar. Certainly there are more data points to consider. What I believe remains hard to debate is that Furuno seems still in the lead of radar tech for the cruiser/small fishing boat crowd, a distinction I’ve always found a bit artificial in the first place.

Eivind Haugan

Hi, Interesting discussions.
As fog and dark nights are few and far between for us sailors in the South Eastern part of Norway, unless we are brave enough to sail during the winter, I haven’t had a radar on board my boat and haven’t missed either. But as we are now planning for a trip to the Caribbean I bought one with an autumn discount a few months back to install this spring.
However this thread makes me wonder if I have made a mistake in my purchase, as I have bought a B&G (Simrad) 4G radar to integrate with my Zeus 12″ MFD display and B&G H3000 system. My reasoning for the choice was recommendation from a few friends, easy integration (I have no good place to put a separate screen) and also B&G reputation as the choice for sailors.
So I’m now just hoping that it’s not as bad a choice as the thread suggest, or maybe we can hope to be lucky and not be to bothered with fog and bad visibility. I will try to post an update later with my experience with this setup.
A point I might have missed is if the experts among you have a recommendation for minimum height for a stern mounted radar that is gimballed. Any suggestions?
Regards Eivind / Abraxas 3 / NOR-12050

John Harries

Hi Eivind,

Hopefully B&G will sort their issues out. As I understand it, most of the issues are software ones, so they should be able to fix things with upgrades.

As to Radar height, Ours is about 10 feet above the deck (just high enough that the radar beam does not hit crew in the cockpit) and that would be about 15 above the water. This height has always worked well for us.

Henning

Marc,

True Echo Trails are a desirable feature of a proper radar but these were not mentioned in this discussion so far as I can see.
There are a bunch of trues and relatives in radar terminology. Let me try this definition and please correct me if needed:

How the display is controlled:
Relative motion display: Your boat stays at the center and all other targets move. It can be hard to distinguish fixed targets (buoys) from moving targets (ships) because they all move across the screen. True echo trails can help with this, but it must be true trails else the land and other fixed features will have trails, too, which is confusing.
True motion display: The display is fixed so land and fixed features do not move. Everything that moves in reality (including your boat) moves on the screen and nothing else. From time to time the display shifts to keep your boat from running off the screen. At first glance this appears clearly superior but the brain has to do extra work. Imagine you would walk the streets of downtown Manhattan. Now imagine you were wearing virtual reality glasses and your eyes would only see an image of yourself from above at 300ft alitutde. Even if you don’t collide with lightpoles or trip over beggars, it would still be hard. You would make a small movement, find it to be in the wrong direction, correct it and then find your correction to again be wrong. The natural link between your vision and your movements would be broken.
I think this is why professional radar operators like ferry captains use relative motion most of the time and only switch to true motion in special situations.

How trails work:
Trails are radar developer’s first attempt to (a) identify moving objects and (b) allow anticipation of future movement. Originally this was implemented simply as an electronically enhanced “afterglow”.
“Dumb” trails on relative motion display: The afterglow clearly does not make much sense in this display type as every target on the screen moves and so has an afterglow. It ends not much more than a big smear and does not help telling moving targets from stationary.
“Dumb” trails on true motion display: Simple trails (afterglow) work much better here. Only moving targets have a trail and the trail is useable to predict future movement. The only problem is that experienced users don’t like to use true motion most of the time.
True trails on relative motion display: This is no longer a simple afterglow and requires serious calculation. It makes trails behave like in true motion display but on relative motion display. It is very useful but found on few or no “recreational” radars (MFDs and their connected radar antennas). But even moderately priced professional standalone sets like the 1815 have it.
Trails are not as precise as a motion vector because they don’t project a forward motion. They will only help a little bit in passing situations.

How motion vectors work:
Motion vectors are not used very much by non-professional users, partly because of ignorance and lack of training and partly because of poor implementation in recreational radars. But they can be the superior answer to my pet question “Will the cruise ship bearing down on me at 18 knots pass ahead or astern (or hit me)?” Such a question does not typically come up in confined waters because you can just stay out of the way of big ships but it will come up on ocean passages and when it does, it will be the only thing that’s on your mind. I have also been in this situation when crossing the English Channel.
You will feel like an astronomer having just identified an asteroid and trying to find out if it will collide with planet earth.
Clearly motion vectors are more useful with large ships that have stable motion and make slow and even turns, not with a water ski boat doing circles around you.
True motion vectors: They are what you are used to from AIS vectors displayed by your chart plotter. Until you get way too close, you don’t really have an answer to the “ahead or astern” question.
Relative motion vectors: If your radar were set to relative motion display and you would plot a target with a felt pen on your screen, then you would create a relative motion vector. Barring course changes, if the target’s relative motion vector points at you, you will collide with that target. If it points ahead or astern of you, it will pass you ahead or astern. Simple and easy.

From the 1815’s user manual (linked above) I find that it supports relative motion vectors:
“7.6.2 Vector time and vector reference
[…]
[Relative]: Other ships’ vectors are displayed relative to your ship. This mode
helps find targets on a collision course. If a ship is on a collision course with your
ship, the vector of a ship points toward your ship position.
[True]: Your ship’s and other ships’ vectors are displayed at their true motions.
This mode helps discriminate between moving and stationary targets.”

To wrap up, I would state:
1. When using radar for it’s original purpose, to give you eyes that can see in the dark and through fog, relative motion display is normally better than true motion.
2. True echo trails are always better than “not true” (dumb) trails, because they make trails useful on relative motion display, but they are rare on MFD-based radars.
3. Motion vectors are generally helpful and relative motion vectors are very helpful in passing situation but also rare in the recreational world.
4. Talking to the typical yacht electronics salesperson about these functions is a waste of time. Only the manual will tell you for sure.

John Harries

Hi Henning,

A very good overview, thank you. And I agree with your conclusions. Two things I would add:

  • A lot of how well much of this will work is dependent on how good our heading sensor is and most cheap yacht quality sensors are not really good enough for more advanced features to work well, particularly on a sailboat in a seaway of any size.
  • Relative motion is one of the toughest things in boating to get clear in our heads and therefore I strongly recommend that everyone learn to do a paper plot to ascertain CPA. No, we probably won’t actually do such a plot on a yacht in real life, but learning to do one makes us much better radar operators because at least we understand the basics.
Marc Dacey

Henning (and John): An excellent explanation. I have some experience with this (true echo trails) on other people’s boats already and find it a desirable feature. The 1815 seems in this respect to be a good choice. I think I should find a “radar terminology primer” and read the manual online. I would be quite prepared to upgrade to a decent heading sensor as I already make use of the elderly fluxgate compass in this regard and I grasp why it matters. I’m also prepared to take a course (or simply to run extensive real-time trials in high visibility and traffic) in order to train myself and my crew in getting the most out of whatever radar we get. Like you both, I’m aware that in high-traffic TSS areas (like the Channel) and on the high seas with a high closing speed between little old us and the Maersk Monstertruck is when my radar and my own skills will have to be most flexible. Thanks for the summary. it is most helpful to me.

Henning

John,

I am happy with my Airmar H2183 heading sensor. When I switched to this heading sensor from my older Simrad that came with the boat, the (also new) autopilot steered a great lot better. I have no complaints about north-up display on my Simrad 4G radar and NSS plotter and chart overlay is stable enough and on the spot (MARPA is flawed on this setup for reasons other than heading input).

Since last season I also have a Vector Compact satellite compass which has not further improved autopilot steering by much (it was already good with the H2183), shows heading fluctuations of a full 10 degrees when docked (which I find odd) and has rebooted several times in mid-operation, causing the boat to go off-course and me to switch back to the H2183 on night passages because I want to sleep off-watch and not fear a crash gybe any moment (these issues are likely related to NMEA2000; in fact, if I were to have a new boat commissioned, I would use MEA0183 mostly and only some isolated and separated NMEA2000). The H2183 (also NMEA2000) never gave this problem and has done 8 1/2 days straight with no hiccup.

I will have to try with a new firmware (which has to be factory-installed) and if that does not help, it was a waste of time and money. A main reason to get it was a collision with a canal wall in the Netherlands Staande Mastroute when we passed over a power cable causing the wheel to go hard-over. I was in the cockpit only 10 feet from the wheel but, in the very narrow canal, couldn’t get to the wheel and disengage the autopilot in time (think twice before you take this route – it’s like driving non-stop on an interstate for 3 days straight). Satellite compasses are supposed to be immune to power cables.

Marc,

you may want to look at Kevin Monahans Radar Book:
https://www.amazon.com/Radar-Book-Effective-Navigation-2008-06-30/dp/B01NH0803M/ref=sr_1_1
It seems to be out of print but I could get a moderately priced used one.
The text does a good job explaining, is very complete and apparently written by a long-time professional mariner.
Peter Hayden recommended it to me.

Marc Dacey

This is a very interesting article on how shortcomings in both training on radar and in the radar’s operation itself played a significant role in what would seem to be an avoidable collision that killed seven sailors.

I find that the reportage of the failures of training and command that led to the incident was interesting of itself, but also has a bearing on how we do passagemaking, particularly in terms of giving ourselves time to master our instruments and to keep room for just being on deck, watching.

https://features.propublica.org/navy-accidents/uss-fitzgerald-destroyer-crash-crystal

By the way, I’ve purchased a Lars Thrane LT-1000 heading sensor for my 1815 radar, with which I am already quite pleased. We’ll see if I’ve made the correct decisions for our vessel after calibration exercises in May.