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Electronic charts dominant

Jun 23, 2010

With the surprise announcement on April 30, 2010, that National Geospatial-Intelligence Agency (NGA) nautical charts would no longer be available in printed form, voyagers are suddenly faced with the necessity of obtaining electronic charts for waters outside of the U.S. whether they like it or not. By the time you read this, there may be a new vendor making NGA paper charts available again, but the future of charting is clear and it doesn’t include large sheets of printed paper.

A few years ago we were sailing south, trying to get below 10° north before the start of hurricane season. After rounding Cabo San Antonio on the west end of Cuba, the prevailing southeast winds came in strong and we could begin to tack to windward, slogging our way down toward our intended landfall in Panama. Day after day the wind was on the nose, sending heavy spray flying over the boat as the thermometer kept climbing with the sun angle, making the cabin into a steam bath. At night we constantly dodged violent thunderstorms. After a few days of this we needed a break, but where to head? Guatemala and even Honduras would have put us well downwind, and the Cayman Islands were behind us.

Our paper sailing chart showed a tiny speck I had vaguely heard of in the middle of the Caribbean — Islas Santanilla (Swan Islands). My trusty Caribbean Reed’s Nautical Almanac had a page map taken from some old Defense Mapping Agency printed chart that is no longer available, some basic sailing directions, and the latitude and longitude of a light located near the western end of the island where the open harbor was located. We decided to set our course for this lonely outpost, hoping we could find it before dark.

I quickly fired up my laptop and began searching through various disks for a chart of the islands, which I had never intended to visit. Yes! I was lucky, there it was in a chart portfolio of obscure islands in the middle of the Caribbean. I had never heard of most of them, but I had the charts, and my navigation program was soon showing our progress toward shelter. We found the low-lying west island, measuring only about 1.5 miles long, and it was just about dark before we were safely anchored in its rolly lee after some rather anxious moments eyeballing our way through the uncharted shallows. Despite the lack of shelter, the lumpy harbor was wonderfully relaxing after many nights of slogging to windward.

Big benefits in small packages
Many of us enjoy the ease of electronic charting in our home waters, but once we head off over the horizon the benefits of being able to carry a huge chart library become even more significant. In fact, as someone who started out and still uses paper charts, pencils, parallel rules, chartplotters, and other non-electronics, I think this is the greatest single benefit of electronic charting. I personally have no difficulty plotting and keeping track of my position using a paper chart, but often in the past it was hard to find, purchase, and physically stow all the charts one might need on a voyage. Today it is very possible to carry every available nautical chart on board in a very small space. Plus, it is possible to download or “unlock” charts that you don’t set out with.

However, as we found out while approaching the Swan Islands, even the best electronic wizardry can be tripped up by the reliance on oceanographic and cartographic data created by people working with 18th, 19th, and early 20th century technology. Electronic charts look fantastic on the screen of your computer, and the amazing ability of your GPS to put an instant track on the chart can lull you into a false sense of security, as we found out later on our trip when approaching Isla de Providencia, an island owned by Colombia.

The tall mountains of Providencia were easy to spot from a long way off, but the sailing directions weren’t clear. We had a cruiser’s GPS waypoint, which can never be fully trusted, to find the entrance buoy, and then there were supposed to be some other buoys to follow on a bearing of about 143° magnetic. The electronic chart looked good and was showing our track steadily approaching the island, but we abruptly realized something was wrong. Depths were dropping too fast, we could see coral coming up from the bottom. We had to back off, looking around for the various landmarks listed in the ancient sailing directions. The charting program showed us well to the north and west of our actual location. Once we arrived safely at anchor in Catalina harbor we were quickly greeted by other voyagers, and we learned that nobody’s electronic charting systems had them in quite the right spot, the charted depths were inaccurate, and lots of aids to navigation weren’t shown properly.

The available charts of the islands were obviously of 19th century origin, with beautiful hand-drawn features. Apparently, the original cartographers either got the latitude/longitude wrong, or in subsequent moves to different chart datums someone later on didn’t make the shift. Whatever the reason, this is a frequent problem in lesser traveled waters, and even in some parts of more developed countries. And, this problem has not been cured by converting paper charts to digital versions. Later, on our trip to the southwest Caribbean, we found submerged reefs that were charted as breaking the surface, and even small islands that were now missing. The lesson is that no matter how up-to-date your charts and your equipment, all of these systems rely in the end on hydrographic surveys done by government agencies that may or may not be accurate.

Paper or plastic?
What should you look for in a voyaging charting system? Number one in my book is the availability and type of charts. As of this printing, the NGA is making available a Digital Nautical Chart for waters outside the U.S., but it is only for federal vessels. This is a vector-based digital database created from information formerly found on approximately 5,000 paper charts that voyagers once used on board.
According to the Federal Aviation Administration, it stopped selling NGA charts as of the end of April, but it is actively looking for another vendor to take over this vital service.

If you need paper charts, check with major chart suppliers like Bluewater Books & Charts in Florida and Rhode Island or Landfall Navigation in Connecticut. They may still have stocks of NGA paper charts, which are required for events like the Bermuda Race, taking place in June. Another English-language alternative is to seek British Admiralty (BA) paper charts, which retail in the U.S. for more than $40 each. However, BA charts are only stocked by very few vendors, and they generally do not carry many.

The cutting edge and the future is in digital vector charting, but many charts are still only available in the raster format. Briefly, vector charts are formed using layers of digital data that can be turned on or off, updated independently of other data, or merged with other databases to create different looking products on your screen. Raster charts are basically photo-like images of charts that look like traditional paper charts and have all the information on a single layer.

Despite the current problems obtaining NGA paper charts and digital data, the National Oceanic and Atmospheric Administration (NOAA) is still producing and making available both paper charts and electronic versions, in both raster and vector formats of all U.S. waters. In fact, users may download these charts for free (www.nauticalcharts.noaa.gov), or purchase them for a nominal fee from many vendors. NOAA provides a free chart viewer on their Web site, which is a great planning tool (www.nauticalcharts.noaa.gov/mcd/OnLineViewer.html). Just select the charts you want using the viewer and then download them for use in your onboard chartplotter. Though often you can obtain the entire NOAA chart suite for all U.S. waters, including the Virgin Islands, Puerto Rico, Alaska, and the Great Lakes, with the purchase of navigational software or a chartplotter. Many units sold in the U.S. include these charts as standard. Several very useful offshore sailing charts covering large swaths of the Atlantic, the Caribbean, and the Pacific are included in the NOAA portfolio.

NOAA charts are probably the most familiar to many long-time users in the U.S. They look like the “old” paper charts we used to use. However, other companies have created their own proprietary electronic charts in vector format. Major manufacturers include Navionics, Garmin, Jeppesen’s Marine Division’s C-Map, and Maptech. The first three cover U.S. waters and most areas outside of the U.S., while Maptech’s product is basically repackaged NOAA electronic charts with additional tidal and current data. Other companies provide electronic charts for more limited regions. Imray charts cover parts of the Caribbean, the Mediteranean Sea, and northwestern European waters. Canada has licensed their electronic products to be made available by Garmin, among others.

Garmin, Jeppesen, and Navionics are currently engaged in an arms race of providing new and extraordinary features above and beyond what is expected from a traditional nautical chart. Aerial views, satellite views, three-dimensional effects, links to cruising and piloting information, fishing information, tidal information, and more are all available. Things like tides and currents, light lists, and sometimes the aerial photos are particularly useful and can save time from looking things up in books and tables. Typically, these charts are available in a variety of formats, including standard SD memory chips, that can be used with standalone plotters or laptop navigation software.

When it comes down to the basics of providing all of the information found on a paper chart, all of these electronic products will serve you well. You may find that some are better than others in certain regions, usually due to the particular hydrographic data they are based on. In other words, for Canadian waters I would look for a product that utilizes Canadian Hydrographic Service data. Similarly, when cruising the Bahamas I would be very interested in the Garmin, Nobeltec, or C-Map products that utilize Explorer Charts, which I have found to be the best paper chartbooks of the region.

The plot thickens
When ocean voyaging it is desirable to have chart plotting software and/or a dedicated plotter that can handle multiple brands of charts in order to have the best selection. In fact, we found it was sometimes necessary to use some older proprietary formats in electronic products when we were down in the southwestern Caribbean, because that was all that was available from fellow voyagers.

The best of all worlds would be to have both PC-based software and charts and one or more dedicated chartplotters. Dedicated plotters are generally better at or near the steering station, with their higher resistance to moisture, better daylight visibility, and simple operation. They also interface very well with other marine electronics like depth sounders, radar, and AIS receivers.

On the other hand, PC-based systems, generally utilizing standard laptop computers, tend to be much cheaper, often offer much more adaptability to various chart formats, can be reloaded and replaced much more easily, and allow the user to print out charts on standard inkjet or laser printers. I found this latter feature to be very handy. If I don’t have paper charts available, particularly for harbors and close-in coastal work, I will usually print myself out a custom “chartbook” of the area to make sure I have something in case of electronic failure.

Carrying more than one laptop
One huge advantage of using a laptop for chart plotting is the ability to purchase a large screen at a reasonable cost. Many laptops with 15-inch or larger screens cost less than $500 and are perfectly capable of almost any navigational function found on dedicated chartplotter viewers costing three, four, or five times as much. This price difference makes it entirely practical, and advisable, to carry on board two or more computers capable of chart plotting. This redundancy can make up for the lesser ruggedness of laptops when compared to dedicated marine plotters.

Dedicated chartplotters are probably more rugged and reliable than average laptops. However, getting an ordinary PC or laptop repaired or replaced is possible almost everywhere in the world. Chart availability in any digital format is nearly nonexistent in many parts of the world, so stock up when you can and don’t depend on reliable Internet connections for downloads or updates. Paper charts are rapidly going the way of canvas sails and loran. The replacement digital chart products, software, and plotters provide many wonderful enhancements to navigation, but like any boat system, digital charts do not replace the need for a human navigator with a properly booted-up brain utilizing the latest software.    


John Kettlewell is the author of the Intracoastal Waterway Chartbook: Norfolk, Virginia, to Miami, Florida, now in its fifth edition.

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