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Voyager confirms some charts have problems

Jan 1, 2003
From Ocean Navigator #122 May/June 2002

From Ocean Navigator #122 May/June 2002

To the editor: As with his uniquely useful books, Nigel Calder's recent article on chart accuracy ("How accurate are our charts?" Issue 120, March/April 2002) was replete with good detail.

In 2000/2001, my family and I did a North Atlantic circuit on our Kanter 55. We were well stocked with paper and raster electronic charts. Our experiences in different parts of our voyage support Calder's perspective. Certainly, charts in waters of the less industrialized nations at times had significant horizontal datum problems. Recognizing that such situations are unpredictable gave us the necessary healthy skepticism of any GPS/electronic chart fix. We had a rule of thumb that electronic charting and the unique continuous update of position were of a usefulness that increased with distance from any navigational hazard. Which is, of course, the inverse of what would seem logical at first blush.

Having a stash of electronic charts of all scales was, however, a wonderful planning tool, both for passage and anchorage planning, as well as for in-passage decision making. The game of "If we leave/tack/gybe now and lay such-and-such a course, where will we be by dawn/next week?" is so much easier with a mouse than a pencil and stack of paper charts. But as we closed on specific hazards, we tended to ignore the computer and the GPS more and more and resort to seat-of-the-pants eyeball coasting.

One other significant boon that the electronic chart/GPS duo brings is building confidence in a landfall fix. Our routine on making a landfall was to set up the range rings on the radar and electronic chart to be equivalent, with the approaching coastline in view on both screens. Comparison of how the coastline and other features matched up on each screen in terms of distance and bearing built confidence in our working position. In reality, our coastal pilotage mode was by mutual quality control: my wife at the helm with a paper chart in hand while I watched the screens below, and we compared and contrasted our idea of the best line to follow. It seemed to work. The only time we ran aground was at the Customs dock in Chaguaramus in Trinidad. Stay to the west end if you draw more than six feet.

I should also add that we had more than our fair share of electro-mechanical doom on our cruise, with numerous gear failures. Time and again I would turn away in disgust from a technical manual that failed to tell me what I needed to know. I would turn to Calder's Boatowner's Electrical and Mechanical Guide to learn the principles of whatever it was that was broke, and then would quietly go ahead and fix it. Calder's words and pictures are a godsend to all voyagers that cut the boatyard umbilicus.

Michael Moore studies right whales at Woods Hole Oceanographic Institute. He lives in Marion, Mass.

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