Are navionics the best charts?

[JohnGC]

You have gone a bit off piste from the OP’s topic about Navionics, but your comment about Antares is wrong. Antares Charts are all new surveys done by them (look on the website for details) - often of places never surveyed by UKHO, or not surveyed since the days of rowing boats.
But Antares only does detailed charts of Scottish anchorages, so not a Navionics alternative option.

The UKHO doesn't have its own survey assets; they contract out and the Royal Navy does some.

The issues (for me) with Navionics are two fold;
1. The crowd sourced data is dubious. But last time I checked it could be turned off.
2. The Navionics app decluttering algorithm and/or their encoding of "object to display information" at various zoom/declutter settings in the S57 ENCS seems questionable.

Indeed, for point 2, I'd like to find a chart I could use to verify the object display algorithm

It has been suggested to me that Navionics apps dumb down the display for the US market.

It appears that Antares do their own surveys but only for limited areas and their disclaimers don't exactly inspire confidence.
"All our charts have been compiled from our own surveys. Surveying is an art and not a precise science. None of those involved in the surveys have relevant qualifications and no warranty is offered as to accuracy or completeness. To enable you to decide whether you wish to use the charts we have set out the general approach taken, although do not guarantee that it was followed precisely in every case.

Antares are far better than anything offered by the HKHO in the same areas.

The UKHO doesn't have any in house survey assets. They either contract out, buy from harbour authorities or use Royal Navy surveys.

 

[ghostlymoron]

The UKHO doesn't have its own survey assets; they contract out and the Royal Navy does some.

The issues (for me) with Navionics are two fold;
1. The crowd sourced data is dubious. But last time I checked it could be turned off.
2. The Navionics app decluttering algorithm and/or their encoding of "object to display information" at various zoom/declutter settings in the S57 ENCS seems questionable.

Indeed, for point 2, I'd like to find a chart I could use to verify the object display algorithm

It has been suggested to me that Navionics apps dumb down the display for the US market.


Antares are far better than anything offered by the HKHO in the same areas.

The UKHO doesn't have any in house survey assets. They either contract out, buy from harbour authorities or use Royal Navy surveys.

But I'm sure they use qualified sub contractors with some degree of QA.

 

[ghostlymoron]

According to the ukho website most of their surveys are carried out by the MCA (coastguards). The surveys are then processed in house and corrections or revisions issued. The Antares procedure sounds a bit more ad hoc to me.

 

[Quandary]

According to the ukho website most of their surveys are carried out by the MCA (coastguards). The surveys are then processed in house and corrections or revisions issued. The Antares procedure sounds a bit more ad hoc to me.

I think that you are making your criticisms from a position of ignorance.
Have you seen the boat and equipment that bob Bradfield uses, watched them in action or ever used the product he produces?
The statements on the site are disclaimers for legal protection but as Dunedin advises there is nothing as detailed or accurate for the inshore anchorages we use up here. Antares charts are produced using GPS and are accurate to within metres, unlike Admiralty charts which were produced long ago and show my boat parked at the top of the cliffs when I am at the pontoons in Loch Aline. The dedication which has been applied in their production , the scope, accuracy and detail, hundresd of anchorages and inshore passages with details of suitability of the bottom for anchoring all for less than £10 a year. We are very fortunate in Scotland to benefit from this, I doubt if there is anything comparable anywhere else.
Bit of a rant, but unqualified and inaccurate posts by folk who have no experience of the subject do wind me up a bit.

 

[ghostlymoron]

I think that you are making your criticisms from a position of ignorance.
Have you seen the boat and equipment that bob Bradfield uses, watched them in action or ever used the product he produces?
The statements on the site are disclaimers for legal protection but as Dunedin advises there is nothing as detailed or accurate for the inshore anchorages we use up here. Antares charts are produced using GPS and are accurate to within metres, unlike Admiralty charts which were produced long ago and show my boat parked at the top of the cliffs when I am at the pontoons in Loch Aline. The dedication which has been applied in their production , the scope, accuracy and detail, hundresd of anchorages and inshore passages with details of suitability of the bottom for anchoring all for less than £10 a year. We are very fortunate in Scotland to benefit from this, I doubt if there is anything comparable anywhere else.
Bit of a rant, but unqualified and inaccurate posts by folk who have no experience of the subject do wind me up a bit.

On the bottom left of all admiralty charts is a note giving the date of the survey the chart is based on. As you rightly say, many surveys were carried out before the advent of GPS.
A lot of modern charts contain errors for various reasons (I reported one to Navionics last year which has now been corrected - a label not a feature).
I understand that MCA also use GPS in carrying out their surveys and also use qualified staff.

 

[Rappey]

.Like Paul rainbow I also have a dislike with navionics.
After buying a chart package then not long after buying a newer phone it would not work.
Navionics help told me I had to buy it again so it would be compatible with new phone.
Have a look at c-map explore app. Free charts with auto routing but have to be online for it to work. Beautifully clear on a 10" tablet.
Have an onwa chart plotter, built in ais tranceiver, super fast cold start location, takes cmap or navionics and has free world wide charts,UK ones based on admiralty charts.
+1 for mx mariner as it's so cheap

 

[tudorsailor]

I just loaded C-Map onto my android phone. While connected to the internet I tried to look at Corfu chart. The coastal area is all hatched out with the message that the chart is only available with Embark Premium.
Back to Navionics for me..............

TudorSailor

 

[AntarcticPilot]

According to the ukho website most of their surveys are carried out by the MCA (coastguards). The surveys are then processed in house and corrections or revisions issued. The Antares procedure sounds a bit more ad hoc to me.

UKHO certainly carry out their own QA on all the charts they produce; I have been part of the procedure for Antarctic charts. And, while they don't directly control hydrographic resources, they are the main (only?) customer of the RN's hydrographic resources and quite reasonably rely on the MCA, harbour authorities' and other local sources in places where there are other commercial reasons for surveying or in areas of rapid change. Note also that the UKHO produces charts of many parts of the world besides the British Isles, and for these, their main data source is RN hydrographic surveys, as well as input from other hydrographic surveys from vessels such as the RRS fleet, though these are usually of very deep water and so hardly of interest for navigation.

Antares produce charts that are at least as good as anything produced by other agencies. However, they don't benefit from either Public Interest Immunity or have deep pockets. Further, they are charting places where it would be very easy to miss an isolated danger. Therefore, they use a disclaimer which looks very similar to those we used on maps of Antarctica; that is to say, they give an indication of their methodology and tell people to be aware that they could be in error and to use their own judgement. We used a phrase that they could, perhaps, usefully employ: "The absence of a feature on the map does NOT indicate the absence of a feature on the ground". This is just about the only reliable way of limiting liability in these cases; it doesn't get them out of a situation where they haven't charted a glaringly obvious danger (which would count as negligence), but it does get them out of liability for errors because they put the user on notice that there could be errors. I imagine (I haven't looked!) that the small print for all non-HO chart products has similar disclaimers; they would be foolish not to.

I haven't used Antares charts, but I've seen some of their work and have been favourably impressed by it. I speak from over 30 years of experience of map-making! I was initially a bit doubtful of their ability to produce accurate depth data, but they seem to have cracked it. A final point is that all their surveys are of small areas within which it isn't too hard to produce consistent tidal corrections, and they don't attempt to provide a wider charting facility - their charts are of anchorages and narrow passages only passable by small-craft like ours.

 

[dunedin]

According to the ukho website most of their surveys are carried out by the MCA (coastguards). The surveys are then processed in house and corrections or revisions issued. The Antares procedure sounds a bit more ad hoc to me.

Antares Charts procedures are far from ad hoc. And have supplied many corrections to UKHO charts - reporting dangerous rocks not on Admiralty charts, removing imaginary islands etc. These have now been corrected by UKHO and hence filtered out to Navionics and others.
At a recent talk it was stated that the side scan sonar used for the "official" surveys cannot work in waters less than 5m - so useful for ship channels but not for yacht anchorages.

 

[AntarcticPilot]

Antares Charts procedures are far from ad hoc. And have supplied many corrections to UKHO charts - reporting dangerous rocks not on Admiralty charts, removing imaginary islands etc. These have now been corrected by UKHO and hence filtered out to Navionics and others.
At a recent talk it was stated that the side scan sonar used for the "official" surveys cannot work in waters less than 5m - so useful for ship channels but not for yacht anchorages.

Both side-scan sonar and swath bathymetry require deeper water than we operate in! The ones on the RSS James Clark Ross had a minimum depth in 10s of metres (I forget exactly), but they were intended for sounding continental shelves and deep oceans. Further, if they were being used for hydrographic purposes, they had to be calibrated at intervals using Conductivity-Temperature-Depth casts that required dangling instruments on a cable all the way to the bottom. I don't know how they calibrate them in shallower water, but as the speed of sound in water depends on both the temperature of the water and its salinity, I guess they must have ways to calibrate it for shallower surveys. There must be a problem in some areas that the temperature and salinity vary rapidly horizontally as well as vertically (imagine a river discharging fresh water into the sea).