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Having Multiple Sources of Cartographic Information

One of the nice things about working for a sailing magazine is that people often just send you stuff hoping you’ll try it out. This was particularly true of paper charts, back in the day when people commonly used such things, which is why I have an unusually large collection, particularly of Caribbean charts. Many of these came from Don Street, who never sent me copies of his own Imray/Iolaire charts (he always insisted I actually buy those), but instead sent copies of other people’s charts with extensive handwritten notations he had made showing where they were wrong.

What was remarkable about Don’s notes was not only how extensive they were, but where they were. Many were found in the middle of awful rubble-strewn reefs, places where no one in their right mind would ever think of taking a sailboat, remarking that such-and-such a rock or coral head was shown out of position. One could only wonder how it was Don ever made such alarming discoveries.

The point being, at least when it came to sailing the Caribbean, I was spoiled for a long time and had many different charts to consult, and what I learned from this is that all charts (even Don’s) are wrong sometimes. And the more different types of charts you have to consult, the easier it is to anticipate when and where they are wrong.

Just last year I broke down and finally started using my iPad as an on-deck chartplotter (my regular plotter is down below at the nav desk) and was very glad I did. For one thing, when sailing with my young daughter, I can now forestall her incessant query—“How long until we get there?”—by handing her the iPad and telling her to figure it out for herself. More importantly, with the iPad aboard I now have more charts to consult wherever I am. Between my paper charts, the charts on my regular plotter and the three different charts available via the Navionics app on my iPad (their regular charts, their Sonar Charts, plus free NOAA vector charts) I usually can quickly consult five different sources of cartographic information.

Often, of course, this isn’t necessary, but I’ve been surprised by how frequently my charts are in disagreement. Nowadays when coming into what looks to be a tricky anchorage or harbor, I check my different charts and if they don’t agree I assume they must all be wrong until proven otherwise. In some cases they actually are all wrong in different, unique ways.

This, I’ve decided, is what I like best about electronic navigation—that it makes it much easier to follow the most important dictum of traditional navigation, which is that you should never rely on just one source of information. Some people are seduced by the simple convenience of modern electronics and end up relying on just one device out of sheer laziness, and there are more than enough tales, apocryphal and otherwise, to illustrate why this is a bad idea. The story of the Vestas Wind grounding is currently quite popular, but my own personal favorite involves a Nordic 40, Seaquel, that crashed in Hawaii last summer after its owner’s iPad froze up at just the wrong moment because Apple for some reason wanted it logged into iCloud.

Done properly, I think electronic navigation should make you less, not more, complacent. Carry more charts and compare them to each other, and you’ll quickly view them all with increased skepticism. In some utopian crowd-sourced e-nav data future we’ll no doubt all be Don Street, scrawling notes on each other’s charts with lots of circles and arrows and exclamation points. That way maybe we’ll someday collectively create a set of charts we can actually rely on.

SAIL’s Cruising Editor Charles J. Doane sails his Tanton 39 on the Maine coast and down in the West Indies whenever he gets the chance. He is the author of The Modern Cruising Sailboat, published by International Marine, and is a contributing blogger at SAILfeed.com.

November 2015

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