sail-world.com -- Paper charts essential for the prudent sailor - or are they?
Paper charts essential for the prudent sailor - or are they?
Fri, 29 Mar 2013
Ocean Cruising Club Award winners Neil & Ley Langford are longtime, tech-savvy cruising sailors who install and manage most of the systems and technology onboard their New Zealand-designed Crystal Blues. They are currently in South East Asia. Recently Neil set about reviewing their collection of paper charts and disposing of some. But what he discovered instead was surprising in more ways than one:
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 ?
Look at the images immediately above and below this paragraph, then compare them with the old paper chart image at the top - its the same area - there is so much more information readily available in the modern electronic systems.
Fact is that we have four fully functional electronic chart systems on board - two computers that run Transas Navigator and Open CPN, plus two iPads running Navionics HD and various other charting or mapping programs. 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 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So, should we continue to carry around hundreds and hundreds of paper charts, most of which are inevitably out of date and not corrected ?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 group, an early black & white original print with beautiful hand corrections running through to (gulp) 1988. We probably obtained this from a merchant ship that was clearing old charts - we have some that came from military vessels as well.
Of course the first deficiency is the updates - no cruising sailor I've ever met has carried properly updated paper charts for their entire collection. The second deficiency is accuracy. That Fiji chart that I selected was first published in 1878, with large corrections in 1915, 1939 and 1962.
Then we had 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 those paper charts.
I found the same issues with almost every chart I reviewed. They are beautiful works of art, but too much information is simply missing, unless you carry every detailed chart on issue.
Here above is Ascension Island, a tiny dot in the South Atlantic. In the North west corner is Clarence Bay, the subject of this comparison.
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 by the policy that we would always have detailed paper chart coverage, to backup the electronic systems onboard. That policy has now changed. We've decided to carry only large scale paper charts that provide oceanic coverage over perhaps 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 inches 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 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 ? Possibly 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 the GPS system, but also from the Russian Glonass system, and from the European Galileo system, providing a large degree of redundancy. Others 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.
Bad Elf GPS for wifi-only 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 iPad training sessions for cruising folk here at Yacht Haven Marina. Unfortunately more than one has purchased the wi-fi only version of the iPad, which has no GPS positioning system - it cannot work properly with any navigation system.
If you want to use the iPad for navigation, you must buy the model that has 3G/4G network capability. Only those models have the necessary position sensors. If you do unfortunately have the wi-fi only version, you can add GPS capability to the unit by using the excellent Bad Elf external GPS module. Two versions are available, one with a cable connection and the other using Bluetooth.
To follow the travels and experiences of Ley and Neil Langford on their cruising yacht Crystal Blues, go to their Blogspot?nid=107909 where they first published this insightful article.