Plot twists

The debate as to whether a paper or electronic chart is the better for the contemporary sailor has been going on for years. To some extent, the answer is subjective, even nationalistic. The British, for example, tend to be more conservative about their boating than Americans, who love their gadgets.

It is this conservatism in Europe that has made a success of a device known as the Yeoman plotter. The Yeoman is an intermediate technology that lies somewhere between paper charts and fully electronic navigation. It consists of a base plate in which an electronic grid is embedded. A conventional paper chart is attached to this plate, and the grid replicates the lines of latitude and longitude on the chart. A GPS is wired into the system and connected to a movable devicelike a computer mousethat contains an LCD display screen, with four lighted indicator arrows arranged around a small plotting hole in a clear piece of plastic. When the plotting hole is located over the boat’s latitude and longitude, all the arrows turn off; at any other time, the relevant arrows light to indicate in which direction the device must be moved to find the boat’s position on the paper chart.

The Yeoman company calls this system "The Mouse for Maps." I have found it to work exceptionally well. Once the system is initialized to a chart, it is literally child’s play to find the boat’s position (our children have done it for years). There are numerous other sophisticated functions built into the system’s software, such as programmable waypoints and routes, time to go, and course and speed, as well as the ability to obtain position, range, and bearing; in short, all the kinds of functions associated with fully electronic navigation devices.

This technology was introduced to the U.S. by KVH Industries (the KVH Quadro system) a few years ago. We had an early model that we adapted to make charts for our cruising guide to Cuba. I loved it, but the sales volume was insufficient to keep KVH in the business. Later, the Better Boating Association (publishers of the well-known Chart Kits, now owned by Maptech) marketed the system. Recently, Yeoman set up its own North American operation, and it is hoping to crack the technology-oriented U.S. market. Yeoman sent me its latest "Sport" model to test and evaluate.

For comparison purposes, I decided to also test one of the latest-generation of fully electronic chart plotters alongside the Yeoman. C-Map was good enough to lend me a Magellan 6500, which utilizes C-Map’s latest electronic-chart technology, C-Map NT. The unit, at a catalog price of $849 (according to West Marine web site,, is broadly similar in price to the Yeoman Sport XL ($700 list price), although by the time a GPS is added to the Yeoman its price will be higher (the Magellan has a built-in GPS). The 6500 will then need the relevant chart cartridges while the Yeoman will need charts, with prices once again being broadly comparable for similar chart coverage.

When it comes to electronic charting, there are two ways to convert traditional paper charts to an electronic format. One is to simply scan the charta raster scanwhile the other is to convert the information on the chart into an electronic database in which all the information is stored according to its latitude and longitudea vector-based system. Handling raster scans requires large amounts of memory, generally beyond the capability of a cockpit chart plotter. Vector-based systems take far less memory, and, in any case, can be readily simplified to accommodate the memory and computing capabilities of a specific chart plotter; thus, they are used in all chart plotters. But the more the system is simplified, the less the detail on the resulting charts, and the less their utility.

The latest generation of chart plotters have a tremendous amount of inshore detail, covering all the complex channels, islands and ledges on our back doorstep in mid-coast Maine. And, of course, just as with the Yeoman plotter, it has a dozen other features, including waypoints, routes, time to go, bearings, distance off, and so on.

Installation issues

The chart plotter can either be installed on a mounting bracket, or else can be fitted into a bulkhead or an instrument pod at the binnacle. Connection to the boat’s DC system is simplicity itself if the unit is to be used as a stand-alone unit (it requires a positive and negative connection), but this gets more complicated if the plotter is to be integrated with other electronics (an autopilot, etc.). The Magellan 6500 has its own built-in 10-channel GPS receiver. This has a small antenna that needs to be located in some reasonably unobstructed area abovedecks, with the antenna cable routed back to the chart plotter. There is nothing here that is beyond the talents of most boat owners and nothing that is terribly time consuming, although the need to cut into a bulkhead for a bulkhead mount will be intimidating to some.

The Yeoman is even easier to install. Since it is a freestanding unit, there is no requirement for mounting brackets or modifications to the boat. Some models come with a built-in 12-channel GPS (the Yeoman GPS Sport XL, list price $999), in which case the wiring requirements are almost identical to those of a chart plotter: a simple positive and negative connection to get the unit up and running and some more complex connections to integrate it with other electronics. There will also be a GPS antenna that needs an abovedecks mount. For those models without a GPS, a receiver must be bought separately and wired to the Yeoman through a pigtail with four to six connections.

Being portable, the Yeoman can be used wherever there is a power supply. If not integrated with other electronics, and as long as the GPS is integrated with the Yeoman the whole package can be readily taken on and off a boat, used in a car, and so on. If the Yeoman is integrated with other on-board electronics or hard-wired into the boat’s DC system, its range of movement will be limited by the length of its power cord.

One of the principal differences between the Yeoman Sport XL and its predecessors is the fact that it is more or less waterproof, with the chart contained in a plastic bag that protects it from the weather. This being the case, I hard-wired it to my boat’s DC system with a cable length that would allow me to use it both in the navigation station and also out in the cockpit. This installation gave me a degree of versatility not available with the chart plotter but resulted in an annoying amount of cable, particularly when the GPS cable was factored in (note that Yeoman is working on a wireless version that will eliminate much of the cabling).

Instantaneous fixes

To put the Yeoman and the Magellan through their paces, I went for a sail in the estuary of the Sheepscot River in Maine. The lower part of the river abounds in small islands, rocks, abrupt granite ledges, and narrow passages with sometimes strong tidal currents. Navigation can be quite complex, with little time to do the necessary chart work. As an added hazard, dense fog will sometimes blow in from offshore with little or no warning. If ever there was an environment in which a navigator will benefit from some form of automated navigation system, this is it. In these challenging circumstances, I found both units operated superbly, giving me constantly updated fixes; there were, however, some distinct differences in functionality.

When placed in the cockpit, the Yeoman was ready for almost instant use. Nevertheless, it took a few seconds to move the "mouse" around until the lights went out and a fix was obtained. And every time a new position was wanted, I had to repeat the procedure. Although the mouse can be manipulated with a single hand in calm weather, which means that if the unit can be placed close to the wheel or tiller it is possible to get a fix while steering, in general, use of the Yeoman is a two-handed operation. When sailing short-handedI used the system both with and without crewthere are moments when you simply cannot desert the helm for the time required to get a fix. And, of course, if you are singlehanding a skittish boat without an autopilot, as soon as you remove your hands from the wheel or tiller the boat is likely to take off in the wrong direction!

In contrast, the chart plotter can be set up right at the helm station, which is where I would definitely want it, rather than down below. Here it automatically displays the boat’s position with constantly updated fixes so that at all times there is no question about where you are. This is a no-handsor at worst a one-handed (to push the buttons)operation, with never any need to desert the helm or let go of the wheel or tiller. I used the Magellan to thread my way between a number of rocks and ledges to which I normally give a pretty wide berth. It displayed every one with impressive clarity and made the navigation a piece of cake. If it’s an instantaneous position fix you want, the chart plotter may well be the best way to get it.

But there’s more to the picture than this. The physical size of the Yeoman, which makes it a little awkward in the cockpit and sometimes on the chart table, is, in reality, one of its principal advantages. The screen on even the largest of chart plotters is a fraction of the size of the chart area that can be accommodated by the Yeoman. This leaves the user of the chart plotter with a choice: either to have coverage of a reasonably large area but with no detail, or else to narrow down the area and increase the level of detail. The smaller the area covered, the less the peripheral vision for the navigator.

Threading these channels, I found that by the time I had sufficient detail for the chart plotter to shine I had insufficient area coverage to maintain much sense of the waters around me, which was quite disconcerting. You can, of course, zoom in and out, but this takes time, which is the one thing that may not be availableit is also a little disorienting because of the sometimes quite dramatic changes in the level of displayed detail. Ultimately, no amount of zooming can compensate for the small screen size. I found myself reaching for the chart, or the Yeoman, to put the plotter picture in perspective.

The Yeoman, in allowing a substantial area of a conventional chart to be displayed at any time, puts the navigator in a familiar paper-chart environment, which can be comforting at moments of stress. All navigational choices are immediately apparentthat is, until you get to the edge of the chart, at which point the chart must be removed, refolded or replaced, and re-initialized. The smart navigator will have pre-selected charts and pre-programmed the initialization points so that this can all be done relatively quickly and easily; nevertheless, it is a more complicated and time-consuming than moving to another chart in the chart plotter’s inventory. Full-size charts used with a Yeoman also end up with a lot of creases in them. Chart Kits, however, do just fine, since the system is designed to accommodate these charts without folding. The Yeoman also comes with Chart Kit initialization points pre-programmed, which greatly speeds up and simplifies the set-up process.

Color and readability

Without question, the single biggest advantage of the Yeoman is this use of paper charts in all their color glory. Charts have undergone centuries of evolution. The modern chart has an unbelievable amount of detail presented in an extremely readable fashion. It is nothing short of a work of art. The Yeoman is able to fully capitalize on the benefits of this evolution.

There is simply no way a monochrome chart plotter can replicate the readability of a chart (almost all chart plotters are monochrome at the present time, although a few high-end units are going to color, with prices at discount stores starting at around $1,300 and ranging up to close to $10,000 for a large-screen model). Once you take the color out of the picture, the details become significantly more confusing. In particular, with many chart plotters you have to interpret the numbers to figure out the location of shoal water, as opposed to it jumping off the page at you. However, with the Magellan 6500 you can program the device to shade in all water below a user-selected and -adjustable depth. This is a tremendously valuable feature that instantly clarified otherwise confusing situations. It is also one of the benefits of the vector-based technology underlying this chart plotteryou can’t do this kind of thing with raster images.

I did find some anomalous glitches with the application of this vector technology. At maximum zoom, everything was legible, although, as I mentioned earlier, the area covered was too small to be of much use. As I zoomed out, I found some of the soundings on top of each other. At times I had to once again read the paper chart to interpret the chart plotter. Continuing to zoom out, I ran into the same problem of overlaid data a couple of zoom steps later. All in all, had this been my first time in these waters, with the fog closing in, I would have been somewhat confused.

As with all monochrome chart plotters, this chart plotter can also be hard to read in certain light conditions, no matter how much the brightness and contrast are adjusted. Many of the color plotters are also hard to read in bright sunlight, although some of the newer (and expensive) models do just fine. A chart, of course, gets easier to read as the light gets brighter. However, it should be noted that the little position-indicating lights on the Yeoman mouse cannot be made out in sunlight. It is necessary to create a shadow over them to see if they are on and to tell when they go out.

Curiously, I found that the soundings on the chart plotter differed somewhat in location and depth from those on the chart (the result, I believe, of C-Map converting from feet to meters for its database and then back to feet for American users). One sounding was just plain wrong. C-Map does not do its own survey work, so clearly what is at stake here is an interpretation by the person doing the digitizing. The nature of vector-based chart-making, which records lines as a series of connected points, also results in the depth contours being straightened out to some extent, losing some of the finer details.

Fundamentally, the quality of the hydrographic data displayed by a chart plotter is dependent on the quality of the digitizing process. C-Map is a high-end producer with rigid quality-control standards (C-Map may just be unlucky; the mistake I found might be the only one in a million soundings!), but nevertheless there are bound to be some errors compared with the paper charts. That’s the negative side.

The positive side is that the nature of a vector-based electronic chart is such that it readily lends itself to corrections, additions, and modifications, whereas a paper chart, once printed, is pretty much cast in stone until the next edition (an infrequent event in today’s climate of budget cuts). In-between editions, corrections, and additions to the paper chart can only be determined by monitoring Notices to Mariners, and then entering the changes by hand, something done by few pleasure boaters. Vector-based electronic charts, on the other hand, can be readily corrected and updated.

It is also possible to add a wealth of useful information garnered from other sources, such as ports and tides data, fuel docks, launching ramps, and maybe even the nearest supermarket. The chart plotter we used went so far as to display the individual docks at our boatyard.

Difficult choices

All of which goes to show that, for every argument in favor of a Yeoman-type device, a counter argument can be made for a chart plotter. And this is without considering price, which I have mostly left out of the picture because of the volatility of the cost of modern electronic devices. Nevertheless, one fact stands out: whatever electronic system is used, paper charts must still be carried. The chart-plotter manual reinforces this by emphasizing that the unit is a supplement to, and not a substitute for, paper charts. Given that these paper charts are going to be on board, a Yeoman is the cheapest way to get into electronic charting simply because it requires no additional expenditure on chart cartridges.

If I had to make a choice between a Yeoman and a chart plotter, this is one of the reasons it would likely be in favor of the Yeoman. But more than just being the cheapest way to get into electronic charting, I value the clarity of the detail on paper charts and the sense of peripheral vision they and the Yeoman give, over the ease of use and compactness of a chart plotter. This is clearly a very personal choice which to some extent runs counter to the direction the marketplace is taking.

I am also one of those people who likes to plot fixes on a chart so that if the system goes down I will have a recent position to refer to, and from which to start running my dead reckoning. A chart plotter will record these fixes and the boat’s track, but if the system fails the fixes and track go with it. (Of course, if the system does not go down, the chart plotter will produce a complete record of the boat’s voyage, which is a pretty neat feature.) The Yeoman Sport XL comes with an erasable pen that can be used for plotting on the transparent chart cover, while other Yeoman models allow direct plotting on the chart itself. If the Yeoman goes down, the plot remains.

At the end of the day, it is clear that in many respects the Yeoman and Magellan are not so much competitive as complementary. Where one is weak, the other is strong, and vice versa. If cost were not an issue, without a doubt I would have both. The combination of the chart plotter at the helm station and the Yeoman either in the navigation station or out in the cockpit would be dynamite.

If a choice has to be made between the two, it is most likely to be based on personal and subjective grounds rather than on an objective analysis. As you can see from the foregoing, I tend to gravitate toward the more conservative, paper-chart-loving end of the spectrum rather than the electronic end, although as the technology improves and the prices come down I’m willing to be converted.

Contributing editor Nigel Calder is the author of several books, including Boatowner’s Mechanical and Electrical Manual, published by International Marine.

By Ocean Navigator