Navionics charts - wrong, reliable, accurate?

[concentrik]

I was planning on getting the navionics/tablet combination for this year as our venerable CM93/OpenCPN setup lacks detail (depth) in the Balearic anchorages we'll be visiting. But looking at the Navionics detail for Thomas Maestre approach would make you think that only a canoe could get in. Am I missing something (probably, but what)?

 

[duncan99210]

Just opened my copy of Navonics. When originally opened, the screen shot you posted was showing. It then updated itself, showing only a few spot depths but a marked channel running up through the bridge. On the CA Captains Mate app, there are reports of about 2.3m throughout the channel, so the latest update of the chart seems to be reasonably accurate. I have to say that I've found that Navonics updates itself regularly and I've found it to be accurate. And frankly, it's so cheap in comparison with trying to update the plotter charts that I've given up on updating them, using Navonics for close work on harbour approaches.

If you were looking at a 'free sample' version of the app, then it perhaps doesn't have the latest charts on it.

 

[RobbieW]

Interesting observation there Duncan. I too had a look at the Navionic chart, 43XG on my Simrad plotter updated about a month ago (still inside the first year so free), which shows the same picture as the OP. I also use OpenCPN with a 2010 set of charts that shows depths more like those I saw in 2012 (though the bridge was broken at that time). I dont really trust any one set of charts for close work, I try to get a recent pilot or guide to an area which is generally more up to date than the charts I've seen, using Captains Mate is consistent with that - if only I had a tablet, oh well.

 

[concentrik]

I have to say that I've found that Navonics updates itself regularly and I've found it to be accurate. And frankly, it's so cheap in comparison with trying to update the plotter charts that I've given up on updating them, using Navonics for close work on harbour approaches.

Close-in work, yes that's what I had in mind. The update system - does it update the whole chart set area when it updates or only the area you have on screen at the time?

Re Pilots: The latest RCCP Balearics one dates from 2010, 2011 at best and the update pages don't address depth data. Interesting really - I wonder where the depth data published in pilot chartlets originates?

 

[duncan99210]

The way Navonics updates seems to be this. When you zoom in to a locality from the basemap, the detailed chart downloads. That is then kept in the tablet memory. When you open the app again, any updates are offered as a download: today the download for the areas I already have was some 25mb. You can choose to download or not, depending on your internet connection.

 

[LadyInBed]

CM93/OpenCPN setup lacks detail (depth) in the Balearic anchorages we'll be visiting.
Have you checked the Ocpn Advanced Display setup?
There is a slider - Chart zoom/scale Weighting, slide to right to get more detailed chart.

 

[concentrik]

CM93/OpenCPN setup lacks detail (depth) in the Balearic anchorages we'll be visiting.
Have you checked the Ocpn Advanced Display setup?
There is a slider - Chart zoom/scale Weighting, slide to right to get more detailed chart.

Thanks LIB, yes it's set to 5 (max). I'd turn it to 11 if I could...

 

[vyv_cox]

So far as Greek islands are concerned the Navionics app on my iPad2 shows a lot more detail than the latest Garmin Bluechart of the same place. I wrote to Garmin about it: their reply suggests that they do not have a deal with whoever supplies the most detailed version. Having said that, in some areas of Greece detailed charts simply don't exist.

 

[ghostlymoron]

If you look in the bottom right corner, it distictly says 'not to be used for navigation'

I was planning on getting the navionics/tablet combination for this year as our venerable CM93/OpenCPN setup lacks detail (depth) in the Balearic anchorages we'll be visiting. But looking at the Navionics detail for Thomas Maestre approach would make you think that only a canoe could get in. Am I missing something (probably, but what)?

View attachment 50088

 

[LadyInBed]

Just looked at Thomas Maestre approach on my Ocpn and it gives 2.7 N of Port buoy [Fl(4) R 11s] and 2.3 SE of it.

 

[prv]

If you look in the bottom right corner, it distictly says 'not to be used for navigation'

Yes, but that's just the Web app which is a convenient way of having a peek at their coverage.

Pete

 

[concentrik]

If you look in the bottom right corner, it distictly says 'not to be used for navigation'

Sorry, I may have misled you... the screenshot is from the Navionics web page not a chart, hence the warning. It seemed fair to assume that they would use the same 'real' data on the website rather than 'made-up' data. Maybe not, I haven't (yet) bought the Navionics Med & Black Sea chart to compare it to!

Pete you type a lot quicker than me...

 

[prv]

It seemed fair to assume that they would use the same 'real' data on the website

I believe they do, yes. I think the public web app is a spin-off of the download system used to update Navionics+ plotter cards.

When that racing boat hit a reef in the Indian Ocean due to not checking the route at a close-in zoom level, the web app updated within a couple of days to show the reef at wider zooms.

Pete

 

[RobbieW]

Yes, but that's just the Web app which is a convenient way of having a peek at their coverage.

However the OPs picture (WebApp?) shows the same detail as my, just updated, plotter chart of the same area zoomed to the same scale. What Duncan seems to be seeing is different, how on earth are we to be able to tell which is the most up to date representation of data for an area when we both believe we have the latest data from the same supplier? Have emailed Navionics UK with the question, will update with any reply.

 

[mlines]

Mind you, if you read the small print in the terms and conditions of the App it almost says the same thing. It says the app is a guide and the user should be prudent in its use and that you should use the official government charts for navigation!

 

[prv]

Mind you, if you read the small print in the terms and conditions of the App it almost says the same thing. It says the app is a guide and the user should be prudent in its use and that you should use the official government charts for navigation!

And I suspect it says the same thing on the plotter cards as well!

Pete

 

[charles_reed]

So far as Greek islands are concerned the Navionics app on my iPad2 shows a lot more detail than the latest Garmin Bluechart of the same place. I wrote to Garmin about it: their reply suggests that they do not have a deal with whoever supplies the most detailed version. Having said that, in some areas of Greece detailed charts simply don't exist.

I'd very much 2nd Vyv's point, on all detail charts being, to an extent, fictional. My Navionics on high resolution in Greece places the boat a long way from where I know it is and the CMap Ed2, whilst absolutely accurate positionally are obviously for commercial shipping and go into hysterics in >5m.
I found the Navionics for Spanish waters the most imaginative and those for Greek waters (based on Droggie) useful when viewed with a degree of scepticism.

So what happened to that famous Viking pilotage?
I just go slowly when in questionable waters and use the echo sounder. Remember all charts are of past history.

 

[Monique]

Like Vyv, we found our Navionics to be very good in Greece and Turkey.

On the basis of the performance of the iPad based system, we bought Navionics RTW charts for our new Raymarine system.

I am pleased. The positional errors are not the fault of the GPS but the charts are not always WGS 84 compliant. Good basic navigation is still a great asset.

 

[concentrik]

I bought a budget tablet and downloaded both the Boating and the Boating HD apps from Navionics along with the Med&Black Sea charts on a one-day trial. The tablet is 1080 px on the long side, Android 4.4 plenty of RAM and processor power. This is what I found.

1. Navionics puts me about 370 ft out of true position. Tablet is using internal GPS only.

View attachment 50095

2. The graphics are jagged on this tablet. On the web demo they are smooth. It's the same on Boating and Boating HD

View attachment 50097

3. The entrance to Thomas Maestre (where this thread started) seems to have changed again! Not the same as the web display and the graphics are like cartoons.

View attachment 50099

4. The detailed depth display (Sonarcharts option) looks very scratchy and muddled - not so on the web demo.

So I wonder why the position is so far out (my CPN/CM93 is spot on), the graphics are rubbish and Thom Mae seems to change hourly... baffled.

 

[duncan99210]

Might just be worth mentioning that I use an iPad not an Android tablet. I know that there have been a number of threads on here about the various iterations of Navonics on Android, so it is a possibility that although the Android and iPad apps would appear to be the same, they are not exactly the same and don't share the same chart data. Just speculating, no idea of the actuality.