Chart Wars

Like them or not, electronic chart displays (ECDs) are here to stay. And in terms of their contribution to safe, easy navigation, they're second only to the radio-navigation systems (satnav, loran, GPS) that preceded them. Even though you must carry a complete set of paper charts for reference, an ECD interfaced with a GPS or loran lets you instantly see your position on an electronic chart, and creating waypoints and routes is a simple as moving a cursor around on an electronic screen. No more parallel rulers and dividers. No more fighting with uncooperative paper charts in the wind and rain. An ECD handles all the navigation drudgery, and because you can always see your position relative to your intended track, you save navigation time, travel time, and money.

Today's ECDs come in a wide variety of shapes, sizes, and display types. Some use cathode ray tubes (CRTs) to display information, while others use newer LCD technology. In many instances, LCD electronic chart displays are superior to their CRT counterparts. Waterproofing is now possible. Screens are easily readable in direct sunlight. And because they have no TV tubes, LCD units are much thinner that CRTs, and so are more easily installed, particularly on smaller boats or up on the flying bridge.

To see how far LCD ECDs have come, we put seven of them to the test in this head-to-head shootout. Before we get into the results, it's important to note that all of these units display vector charts, which are hand-drawn reproductions of actual paper charts. Raster-scanned charts, on the other hand, are optically scanned copies of paper charts. While they display everything shown on a paper chart and look just like one, raster-charts only work on CRTs and personal computers, and they don't allow you to selectively display chart data like you can with vector charts, and some units have the ability to rotate vector charts into a Course-Up orientation, rather than North-Up, which is a great feature when cross-checking your navigation situation against your radar display.

The Proving Grounds

This test was restricted to the ease-of-use, screen displays, and overall performance of the ECDs themselves. Chart quality is a separate issue (see sidebar comparing C-MAP vs. Navionics charts), as is position accuracy and navigation data. To eliminate the latter from consideration, technicians at Gulfstream Products of Largo, Florida developed a GPS-signal splitter, so we used one GPS to supply data to as many units (four) as would accept it. The other units used their own GPS receivers, but in any event GPS accuracy was not a factor in this test. This test was conducted both at the electronics bench and out on the water, and the results appear either in the writeups that follow or in the comparison table.

Results-General

The first thing we learned is there is almost no similarity in the operating systems among these units. While each unit offered the same basic package of features (nav data, waypoint/route storage and libraries, chart zooming, buoy identification, data outputs to other electronics), there was a vast difference in how you get to those features in the menus. Frankly, some units were easy to use, others were very frustrating.

In addition, two of the units (Garmin and Shipmate) had color LCD screen displays, a long-awaited innovation. But outdoor testing showed color screens have more development work ahead of them--we could not read either of these in direct sun, so these units should be used only in the pilothouse or under some type of cover.

Results—Specific

B&G LCD Chart. Despite its few buttons, the B&G proved to be a feature-packed unit, with several unique, innovative features. One of the biggest frustrations you'll encounter with ECDs is waiting for the chart to redraw when you zoom in and out. If you want to zoom from way out to way in, many units draw each intermediate chart in succession, and you wait. On the B&G, when you want to zoom in or out a menu pops up along the side of the chart and you use the trackpad to choose the chart scale you want. Then the unit goes directly to that chart and draws it in four seconds--almost no waiting. Also, the B&G's chart scales correspond to radar-range scales for easy crosschecking, and the chart scale in use represents the distance from the center of the screen out to the edge. On other units, the so-called chart scale represents the length of a small measuring ruler found in a data box, a system not nearly as good as B&G's.

Another good feature is "Smooth Scroll," which keeps your position in the center of the screen and the chart scrolls beneath it as you move. In addition, a unique "Screen Amplifier" feature automatically moves your position to the bottom 1/3 of the screen once you're moving faster than 4 knots, so you get more visible chart area ahead of you.

When checking a buoy's identity, you must put the big, full-screen crosshairs directly on top of the buoy's dot-symbol (there is no "snap-to" feature), so that's a bit tedious. Also, waypoints are only identified by number, not name, so they're sometimes hard to see amid the clutter on screen. But against that, it's easy to create and edit waypoints and routes, daylight screen visibility is excellent, and overall the unit was fast and easy to use.

Cetrek Chartnav 350. This is not one, but three units in a system--a monochrome LCD screen, control head, and chart reader that can hold up to four C-MAP cartridges. This is a plus for long-range cruisers since the unit will automatically load in the appropriate charts as you move from one cartridge's coverage area to another. Another benefit of the system is its mounting flexibility. But the downside is you have to install, and have the room for, three separate components.

The unit has four primary pages, scrolled through with successive pushes of the PAGE key. The pages are a plotter (chart) display, user-customizable data display, navigation data, and GPS status. You can't go from one to the other without scrolling, and all the buttons on this unit are tough to push. In general the unit is not intuitive, and it was frustrating to create a route--it takes three keystrokes just to get to the route menu. And while the chart redraw time (8.5 seconds) was about average, the unit itself is slow to display data and change screens. Against that, you can name waypoints with up to 16 characters (the most of any unit in this test), and I liked the quick "A-B" function which lets you quickly determine range and bearing between any two points, and the navigation data screens you can show or remove.

Datamarine ChartLINK D7000XT. The was one of the first ECDs built to handle C-MAP's tiny NT cards (it holds two of them). It's the only unit in the group to use a trackball, rather than a sealed directional trackpad, to move the cursor. While the ball is fast (it takes just three seconds to move the cursor across the 7 3/4-inch-wide screen), trackballs are usually a source for water intrusion, so this unit must be mounted away from any spray.

The D7000XT has 18 clearly labeled (but not backlit) keys, plus zoom in and zoom out. Even so, the action really starts at the MENU key, which opens up nine submenus to control screen settings. It's easy to create a waypoint--called a "mark" on this unit--by moving the big cursor to a spot and hitting the MARK key. It's also easy to create a route from existing marks or edit the route, but the process of inserting a new mark into a route is time-consuming and cumbersome. While the unit uses a chart ruler, not a real chart scale, in its data box, and screen redraw time is agonizingly slow at 16 seconds, I liked the fact it had a unique electronic bearing line (EBL) and variable range marker (VRM) feature. The downside to using these, again, is that they are extremely slow to adjust (the VRM expands in 0.01nm increments, and it takes 3 minutes for the EBL to sweep a 3