Thursday, 28 March 2013

Paper Navigation Charts - A Disappearing Story










With The Admiral away in Singapore on a visa run, I was tasked with reviewing our huge collection of paper charts, and disposing of those we don't need to carry.  However, as I sorted through the first of many chart packs, I had a real panic attack - how could we get rid of these ?  They're a treasure trove of information.

For me, they're also an instant connection to the past, rightfully carrying the names of often famous cartographers and navigators.  Many of these charts are beautiful works of art - the land mass is carefully drawn, shaded and defined, not just filled with a color wash as we see on our modern electronic systems.

Onboard Crystal Blues we keep a paper log and an electronic log, so we have a trail of position fixes available if needed.  For years we've told ourselves that if the electronics died we'd transfer those position fixes to paper charts and work from there with conventional navigation tools.  But would we really ?

Examine the images at right, then compare them with the old paper chart image at the top of this screen - its the same area - there is so much more information readily available in the modern electronic systems.

Fact is that we have have four full functional electronic chart systems on board - two computers that run Transas Navigator and Open CPN software, plus two iPads running Navionics HD and various other charting or mapping apps.  How much redundancy do we need ?  What could cause all four of those systems to fail at the same time ? Nothing short of a nuclear holocaust or perhaps a major meteor strike I think.

So, should we continue to carry around hundreds and hundreds of paper charts, most of which are inevitably out of date and not corrected ?



How Do They Compare ?


To dig a little deeper, I selected one of our stored paper charts for the Fiji island group, an early black & white original with beautiful hand corrections running through to (gulp) 1988.

We probably obtained this from a merchant ship that was clearing old charts, though we have some that came from military ships as well.

Of course the first deficiency is the lack of updates - no cruising sailor I've ever met has carried properly updated paper charts for their entire collection.

The second deficiency is accuracy.  That That Fiji chart that i selected was first published in 1878, with large corrections in 1915, 1939 and 1962.

There were further small corrections published through to 1988, when my copy was originally purchased.

However when I compare it to the information available on Transas Navigator or Open CPN there is simply no way that I would want to work with that paper chart.  I found the same issues with many other old charts that I reviewed.  They are beautiful works of art, but too much information is simply missing, unless you carry every detailed chart on issue.


Another Comparison

 Here is Ascension Island, a tiny dot in the South Atlantic.  In the North west corner is Clarence Bay, the subject of this comparison. You can click on these images to enlarge them.






When I look at the detail of Clarence Bay on the paper chart there is a multitude of sounding right into shallow water, clearly intended to support small boat handling in the harbour.  This chart was properly updated and notated through to 1985, but is clearly well out of date now, being based on a 1909 engraving.  Lovely work though !






Here is the same area from our Transas Navigator charts.  Very few soundings in the harbour, though it has enough detail to support prudent navigation.  I think the Transas chart is showing its "big ship" heritage here.






The real surprise is the data found in the Navionics HD package on iPad.  Good detail on the harbour right into shallow water, mooring buoys shown. lead lines etc.  Here is Navionics showing they understand the needs of small boat operators.

So some paper charts have more shore line detail and sounding density than any of our electronic versions, but that detail is usually beyond what we need.

Our Decision


For years we've lived lived by the policy that we would always have detailed paper chart coverage, to backup the electronic systems onboard.

Now we've decided to carry only large scale paper charts that provide oceanic coverage, perhaps over several sheets, for use in passage planning and as emergency plotting aids.  The result is that we've been able to remove a stack of charts almost eight inched high !  Most of course have gone to good homes on other boats.

No GPS - How About Glonass Then ?


It is a frequent topic of conversation among cruising sailors, but I'm guessing that 99% of us would be in serious trouble if the GPS satellite system failed (or was turned off) during an ocean passage.  How good are your sextant skills ?  Probably better than mine I'd say.

However the latest electronic position sensors for the yachting market (from B&G / Simrad / Lowrance) will provide a position fix from the GPS satellite system, but also from the Russian Glonass system, and from the European Galileo system, providing a large degree of redundancy.  Other manufacturers will surely follow.

I was also impressed to see that the latest iPad and iPad Mini also feature Glonass sensors, to supplement the standard GPS positioning system.

iPad WiFi - No GPS


Bad Elf GPS For iPad
Finally, a word of caution for sailors who are contemplating an iPad purchase.  Over the past few weeks I've run a number of informal iPad training sessions for cruising folk here at Yacht Haven Marina.  Unfortunately more than one couple has purchased a wi-fi only version of the iPad, which has no GPS positioning system - it cannot work properly with any marine navigation App.

If you want to use the iPad for navigation you must buy the model that has 3G/4G network compatibility.  Only those models have the necessary position sensors.

If you do unfortunately have the wi-fi only version, you can easily add GPS compatibility to the unit by using the Bad Elf external GPS module.  Two versions are available, one with cable connection and the other using BlueTooth.

6 comments:

  1. Our decision about paper vs electronic charts was the same as yours, only we got rid of a 12" stack of charts, one of the heaviest and bulkiest items on the boat.

    Now, however, in addition to the large scale charts we try to carry a cruising guide, (Hardcopy) of the areas we will be visiting. At least with the chart, a magnetic compass, and the guide book we can get into a harbor and get new electronics, should the entire system some how get destroyed.

    Now, also, with OpenCPN, we can use scanned versions of paper charts, should we find one we just can't part with, which can be added to our OpenCPN catalog of charts, and toggle back and forth from the vector to the scanned version: best of all worlds.

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    Replies
    1. Fred, thanks for sharing your approach. Pity I'm not able to scan everything before we dispose of it......

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  2. A couple of things to ad.

    1. An issue to a lot of users in out of the way places is still resolving datum issues. Yes they still exist, in some data bases, areas that have not been converted to WGS84. Some electronic chart brands do this as well as they can, some not so well and all are constrained by the availability of source data. Using an electronic chart with the ability to overlay a satellite image is the most definitive way to have confidence, or otherwise in the datum of the coast line you are approaching.

    It is easy to think that the chart you down loaded last week must be the latest and up to date. Do not be fooled. Some Chart brands are more proactive than others keeping things up to date but the most common reason for a chart being out of date is just simply that the up to date info is not available. Busy places get updated regularly. Out of the way places may get surveyed every blue moon. Reputable electronic chart systems generally have a way of showing the source data and its date which may vary from one area of a downloaded chart to another.

    2.You mentioned the fact that a number of manufacturers now provide Glonas / GPS Hybrid receivers but failed to mention Garmin were first on the market with this and have combined it with a superfast 10htz processor allowing GPS derived heading and speed over the ground to be as good as you can get at speeds as low as 1 knot

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  3. Thanks Robin, Appreciate your perspective on this. From our conversation yesterday, it seems that Garmin has the latest and best coverage in Indonesia. I'll be interested t hear from others on this issue.

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  4. I wanted to add a bit from our own personal experience with the iPad and Bad Elf. Though it's true it's a somewhat of a hassle to add a GPS dongle to the iPad every time you want to use your navigation app, the Bad Elf costs about the same amount as the difference in price between units and is said to do a MUCH better job of maintaining a signal. I can't speak to this directly because we have the wi-fi only iPad, but we have no complaints about the Bad Elf and once we lock into a signal, it there to stay!

    Stephanie Gardiner
    SV Cambria

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  5. Thanks Stephanie, those who have wi-if only iPads will be encouraged by your comments. I gather you are using the pro version of the Bad Elf, with Bluetooth connection ?

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