Imagine yourself cruising in waters you're not familiar with. What do you do? Pull out your trusty charts and start navigating. Because paper charts are so cumbersome, many boaters have come to rely on electronic versions. But which is the most trustworthy? Which will tell you at a glance exactly where you are and where you should go next? Well, as usual, it's BOATING to the rescue.
Aboard the Crown Pilot, a 36' Hatteras convertible at Landings Marina in Rockland, Maine, we installed two Furuno chartplotters, each loaded with electronic charting software - from C-Map (508/477-8010, www.c-map.com) and Navionics (800/848-5896, www.navionics.com). Then we asked for opinions, which werewhich were freely given by Bob Bernstein, the Crown Pilot's captain; Skip Strong, pilot of the Russian tall ship Mir; Rob Spear and Jeff Cockburn, two Penobscot Bay commercial pilots; and various other first mates and professionals who cared to chime in. These are people who rely on charts for their livelihoods. Their opinions matter.
First, a bit of history. A test such as this would have been impossible a couple of years ago because there wasn't a plotter that would accept both C-Map NT and Navionics charts. Furuno changed all that when it came out with its GP-1850DF plotter. When buying electronic charts, you face two choices: raster or vector. Both are electronic representations of the paper charts boat owners have been buying for years, but vector charts give you more viewing options. They store information in digitized layers in a single database, allowing you to add or delete layers as you need to view them. Some fields of information include depth contour lines under 10 fathoms, soundings, aids to navigation, place names, and so forth.
Both the C-Map and Navionics software used for this test are vector charts formatted for Maine's Penobscot Bay, and each uses a mixture of green, yellow, blue, white, and red to distinguish its features.
A major consideration with any electronic chart is readability: How quickly can you use the display to tell where you are? Once we turn on the machines, it's apparent that C-Map uses its colors more effectively. Strong quickly notes the color benefit: "C-Map's separation of colors is much easier to deal with." This becomes most apparent near shore, where the colors used for land, docks, anchorage areas, water, and channels are nicely differentiated, making it easy to tell where the boat is in relation to a channel, navaid, or point of land. "The color scheme is much easier on the eye," agrees Bernstein. Navionics didn't use as many colors simultaneously, and they lack the strong tonal contrasts of C-Map's colors.
C-Map also clearly displays cans, nuns, and bell buoys - their onscreen shapes resemble their real-life counterparts. Navionics, on the other hand, differentiates each symbol by color display, but they all resemble the symbol for a lighted navaid. Looking from the C-Map screen to the Navionics screen, Spear says of the C-Map display, "It's apparent where you are. You need to get used to the Navionics screen." Part of the confusion, he says, was that the teardrop shape used to identify the Navionics buoys is the same symbol that would be used for a fixed light. He also wonders why both chart companies couldn't stick with the symbols used on the traditional paper chart.
Blame it on age or the need for bifocals, but many of these guys don't like the size of the symbols on the Navionics screen. They find themselves literally leaning in closer to see what lies ahead. C-Map compensates for this with larger icons. Relying on color, as you must with Navionics, to determine what the object is you're coming up to, doesn't always fill the bill. When you're looking at an approaching aid to navigation through the wheelhouse window, "the sun can be positioned so that it's impossible to tell the color of what you're looking at, but you can tell its shape," says Bernstein. "And at night, you often don't know the color, but you can make out the shape of an aid to navigation." That makes it easier to match that shape with a similar one on the C-Map screen.
A plus for Navionics is its automatic display of buoy numbers; C-Map has to be set up by the user to show this information. "It's a nuisance to chase that down," says Spear. Navionics identifies buoys and anchorage areas that aren't identified at first glance on the C-Map display. In either case, with C-Map or Navionics, if you're in doubt about what aid to navigation you're approaching, put the cursor on the object and it will be identified in an information window at the top of the screen.
C-Map has some color problems, too. The dumping-ground buoy is the wrong color, and the sector circles for the navigation lights, which are yellow on the C-Map display, should be white (which is the color you would see at night). Again, you can put the cursor on the dumping-ground buoy and the information window at the top of the screen provides a description. It's just that it takes more time and manipulation to get the information that way, when you should be able to tell just by looking at the screen.