The computers behind the front of chart plotters have long since ceased to be simple computers. The computing power that is now installed here could have rivalled a full-blown office computer just ten years ago.
And the plotters run complete operating systems such as Linux and, more recently, Android.
The apparent chart plotter is just an application programme on an industrial computer in a seaworthy housing. The skipper doesn't notice much of this at first, after switching on - at some point - the electronic chart appears.
With so much effort, one wonders: Why? Especially as a tenth of the installed computing power would suffice to simply display a nautical chart, even with modern vector data. The reason for complex operating systems is largely the customers themselves. Operation with multi-touch, animated graphics, displaying multimedia content, quasi 3D views - these are things that demand a lot from the processor.
Although only briefly, the immediate response is what counts for the user experience in these moments.
Anyone who has used older models will be familiar with the time lag between cursor and image movement, especially if a newer generation card chip with extensive additional information was installed in the device. This built-in decelerator has now virtually disappeared. On the one hand due to fast processors, on the other hand due to skilful software, which does not build up the image in one piece, but in stages: first the rough outlines, then gradually finer and finer details, if the computer has nothing more urgent to do.
The map practically follows the finger on the screen. The user does not notice that details are missing at first. By the time they take a closer look, the computer has filled them in.
The test field
Current plotters can be divided into two groups: thosewith pure touchscreen operation andHybrid devices with buttons and touchscreen. We do not include plotters without touch in this test.
Seven devices are taking part: two each from Simrad, Garmin and Raymarine as well as one from Furuno. The latter manufacturer also has hybrid models in its programme, but not in the 9-inch class.
The obvious rotary knob on the Axiom Pro from Raymarine is actually a multi-talent: its front face also houses a cursor rocker and the OK button. The rotary function is deliberately inhibited to such an extent that a firm grip is required. This proves its worth on a moving base. A button underneath can be freely assigned with functions.
On the Simrad NSS, the cursor field and rotary knob are arranged separately. The latter is easy to turn, but has clearly perceptible detents and is therefore easy to operate even on a moving boat. Two functions from a long list can be assigned to the steering wheel button above the rotary knob, for long or short presses. With Simrad and Raymarine, the rotary wheel in the chart view has a direct effect on the zoom: very practical, especially as the view follows in real time.
You can actually work completely without touch on these two. Garmin takes a different approach: the EchoMap has four programmable buttons and otherwise only a rocker for zooming. Moving the map or route planning can only be done by touch - so it's not a real hybrid.
Automatic route creation
As more and more devices offer autorouting, we have included the function as a test point. The task was to create a route from Damp to Troense in Svendborgsund. The test criteria are the time to determine the route and the practicality of the route. Or should be;the results were unusable for all manufacturers.
There are two reasons for this: Firstly, the Danish South Sea area with its bridges and narrow fairways is not easy even for human navigators. Secondly, the software can only calculate as well as the data situation allows. And the current nautical charts are not designed for marine autorouting.
Devices in cars have it much easier, as they can orientate themselves along predefined roads. On the water, on the other hand, the computer usually drives in the middle of nowhere. We have therefore decided not to evaluate the autorouting function. Besides, trip planning is somehow part of the sailing experience.
Map display
Of course, all devices are capable of the classic display: land yellow, water blue to white depending on depth. In addition, each manufacturer has its own improvements for a stylish map view. The so-called shaded map is very practical. Here, in addition to the depth contours, finer gradations are emphasised in the form of shadows.
In addition, you can create your own colour gradations for all candidates, usually for depths that you can select yourself. However, the question remains as to how the detailed information is obtained, as older official survey data does not provide this resolution. And not all sea areas are surveyed with high resolution by multibeam echo sounder.
It can be exciting to think outside the box: In addition to the official nautical chart data for navigation, most chips contain charts for fishing. Here the depth contours are much narrower, for example in half-metre increments. And many areas outside the fairways are included that are simply labelled as "shallow" in the navigation charts - which offers various new anchorage options.
However, there is a catch: In contrast to the navigator, the fishery is interested in the depth changes; the fish are on the slopes. The absolute value, i.e. whether it is two or three metres below the surface, is less important. The data should therefore be treated with great caution and never used without an echo sounder.
Virtual echo sounder
The function that the plotter uses the chart data to determine whether a shallow area is lurking ahead and warns accordingly is now widespread. Nice to have, but it does not free the skipper from looking at the echo sounder: The chart data does not provide this at all - according to the message when switching on. In addition, the plotter does not know the actual water level. And the minimum depth that can be classified as safe differs depending on the situation: in swell off a lee shore, every skipper will use more than in a sheltered, dredged harbour approach.
Motor in the plotter
All candidates can read in values from appropriately equipped engines via the NMEA 2000 bus and display them on the screen. Either as a virtual dashboard or as a numerical overlay on the map.
You can customise the dashboard window yourself (except for Garmin's EchoMap). Furuno does this very skilfully: If you bring up a rev counter instrument on the screen, the plotter assumes that you want this information from all engines and - depending on the number of engines - places up to four scales with appropriately assigned data.
A second value such as temperature or oil pressure can be set up just as quickly. With all other manufacturers, you have to set up the individual instruments separately for each machine.
In addition to the transmission of measured values, the NMEA 2000 specification also defines the transmission of warnings such as charge indicator light, oil pressure light, engine light, coolant and oil level on the engine side. What the plotters do with this data varies greatly: Simrad, for example, ignores it completely.
Furuno provides the most important ones as an animated symbol and as a message window. Garmin's EchoMap only shows message windows, but no symbols - it is not possible to recognise whether an alarm is still present once it has been confirmed. Raymarine shows almost all messages, only the load control is skipped. There is only an icon for the engine light.
The range calculator compares the remaining tank capacity with the fuel flow of all engines and the speed. The result is how many miles you can still drive with the fuel. The speed comes from the GPS, the fuel flow rate from the engine electronics. Determining the fuel level is difficult. Level sensors only provide the fluid level at the sensor position; how many litres this corresponds to depends on the tank geometry.
In order to obtain a useful indication here, you must use one of the high-quality, programmable transducers and, of course, set it precisely. However, incorrect measurements due to trimming while travelling are still not taken into account.
Another way is via the calculated fuel level: here you tell the plotter when the tank is full and it deducts the fuel consumption reported by the engine accordingly. The technology comes from motor racing, because all fuel level measurements fail during the usual movements. This works surprisingly well today - as long as the plotter is always in operation when the engine is running and you remember to enter the fuel level.
Simrad supports both variants, Garmin only the calculated content. Furuno and Raymarine do not dare to make their own forecasts here, but at least they pass on values that may be reported by the motor electronics.
System opening
Until now, the plotter was a self-contained system, regardless of what was under the bonnet. The end customer without extensive IT knowledge had to live with the software provided by the manufacturer. Raymarine is now taking a completely different approach with the Axiom models: not only is the operating system used (Android) made public - it is even possible to install additional programmes yourself.
Apps that are not actually boot-relevant, such as Spotify and Netflix, are already included as standard.
This could be the start of a new development to turn the on-board plotter into a tablet replacement; this would then be a reversal of the previous trend. From a hardware perspective, this makes sense. Hardly anyone wants to go sailing without their tablet these days, but they are rarely seaworthy and hardly suitable for use in the sun.
What you install on the plotter and which files you download there should be chosen carefully. It would be unfavourable to catch a virus.
Trust
When starting up, all plotters warn against using them as the primary navigation instrument. And pretty much all skippers ignore this warning. However, the test showed that the warning has some merit. In our setup, both Axiom plotters failed after around 20 hours of operation and could no longer be started.
The same behaviour with the replacement device. Strange, because in the demo walls at dealers and at trade fairs, the devices run for many more hours without any problems.
Raymarine was very committed to quickly procuring a replacement. More by chance, our research revealed that this problem had already been observed once before, on a ship where many non-Raymarine transducers were operated in the NMEA 2000 network. In other words, the same scenario as in the test and extremely rare in practice.
When you buy a system, you usually get everything from a single source. It is therefore quite unlikely that this error will occur on board. However, the incident makes it clear that any navigation instrument can fail while underway, no matter how well it worked beforehand. And how important it is to have a chart on board in addition to the chart chips, which can be used without the plotter, preferably without any electronics at all.
Power consumption
On most boats, it doesn't matter what the plotter draws: The engine is running anyway and the alternator supplies more than the electronics need. The theoretical additional consumption due to power generation is not verifiable in practice.
However, energy consumption is a very relevant issue on small boats with an outboard motor without a proper alternator. Here, the operating time of the plotter depends solely on the battery capacity. Large plotters are mainly found on such vehicles in sport fishing, as all the devices in the test include sophisticated fish finders or can be upgraded to include them at a small additional cost.
The display lighting takes first place among battery customers. You will therefore find two power consumption values in the table: the smaller one for night-time operation with a heavily dimmed display and the larger one for daylight operation - here the lighting has to work against the sun.
For example, if you want to go herring fishing for twelve hours with the Furuno (0.95 ampere), it will need around 11.5 ampere hours during this time. You should design a lead-acid battery for at least three times this in favour of the service life; a 12-volt 36 Ah battery would be the closest standard size.
Conclusion
The cheapest model in the 9-inch class is Garmin's EchoMap. It even offers - admittedly partial - operation via buttons and basic motor functions. There is no radar connection. A unique feature here is the ability to quickly remove and reinsert maps from the holder. Together with the low power consumption, this makes it an ideal device for small, open boats.
Above the EchoMap, the 1500 euro class is a close race. Furuno's GP 1971F is a thoroughly solid affair. It comes with a complete, printed German manual.
The motor functions are decent, but unfortunately there is no range calculator. We found the small menus for quick access to frequently used functions practical. These appear when you drag from the edge of the screen to the centre: At the top is the selection of the display page, at the bottom the map display options, and on the right are tools for measuring and waypoint editing.
Furuno scores with WLAN connection for the radar, so only the two-pole power cable is required in the mast. If the 9-inch model is too large: the 7-inch version has the same screen resolution.
The three other touchscreen-only models in the mid-range are in a tie: While Go and Axiom shine with a large selection among the chart formats on offer, the GPSMap has the more comprehensive motor support - but only full-screen dashboard. The competitors are on a par when it comes to the map overlay. The Axiom scores highly in terms of multimedia and its ability to run Android apps - ideal for anyone who wants more than just a plotter.
At the upper price end, the race between Simrad and Raymarine is repeated with an identical outcome: Axiom Pro is ahead in terms of multimedia functionality and competition with the tablet. Simrad, on the other hand, scores with the more universal range calculator based on measured or calculated tank capacity. The priorities are therefore clearly divided.
