Can you trust your charts and plotters?

As we’ve mentioned in previous posts, we prioritize redundancy onboard and never rely on just one chart, GPS receiver, or chart plotter. Over time, however, we’ve noticed a concerning trend: the quality and reliability of digital apps and cartography seem to be deteriorating. This is happening at a time when paper charts are becoming increasingly scarce, which adds to our concerns

Snow Bear is outfitted with high-end Raymarine Axiom plotters—one at the chart table and the other in the cockpit. These plotters are seamlessly integrated with our instrumentation, sensors, autopilot, radar, and AIS, ensuring a fully connected data rich navigation system.

All of this data is transmitted over an onboard wireless network, allowing us to connect iPads (and iPhones) running secondary navigation plotters for added flexibility and redundancy.

When it comes to navigation, the most critical piece of data is our position. For that, we rely on the boat’s dedicated GPS sensors, which provide real-time accuracy, rather than depending on a device GPS, such as the iPad’s built-in sensor, which we’ve found to have noticeable latency.

Is it the Tech?

A couple of years ago TimeZero iBoat and iSailor were both excellent solutions with strong reputations in the market, offering high-quality, regularly updated cartography. Unfortunately, in the wake of market mergers and acquisitions, everything has changed.

TZ iBoat, which once provided reliable C-Map cartography, now delivers subpar, homegrown charts that are riddled with errors and omissions. Meanwhile, iSailor was divested to a Russian company and support is non existent, leaving users in the lurch. Access to the chart store has become unreliable, and it seems that regular chart updates are no longer being provided.

Raymarine’s once promising Lighthouse charts are falling short in both quality and geographical coverage. While bundling large regions together offers good value, the updates are taking far too long to download and maintain.

Navionics and C-Map just don’t seem to grasp the convenience of the digital age. Why on earth should I still receive a physical product—a tiny SD card in plastic packaging—when modern technology makes digital subscriptions a far more efficient option? It’s absurd that I have to find a retailer, provide a shipping address, wait for the card to be mailed, and then, once it finally arrives, the first thing I have to do is update it—by downloading the entire product again.

Or is it the Charts?

Now, enough about the tech—let’s focus on the real issue: the cartography itself. Specifically, the level of detail (or lack thereof), the layout, and how accurately it reflects our position. To illustrate, I’ll use St. Lawrence, NL Harbour, where we’re currently waiting out a winter storm.

Google Earth

We now use Google Earth all the time to plan our arrival into harbours, marinas and anchorages as it tends to be the most accurate depiction of the location and allows us to have a look around at the land features and topography. GPS position will be from the IPads IOS and in this location it’s pretty accurate, maybe just couple of meters from the devices actual position. Taking a proper eyes-on look around this morning this is indeed the current layout for the harbour and its buildings.

Ok, this is not a chart plotter and we don’t suggest you use this for Navigation but remember this image.

Lighthouse Charts on Axiom Display

So this is our primary navigation tool that cost a small fortune. GPS here is from the boats sensor so will be super accurate. This Lighthouse chart has a significant misalignment or georeferencing error and clearly has missing detail. This is not an incorrect setting – it’s just not in the chart for this location. The soundings are nothing like reality. We are in about 7 meters of water and our track looks like we hit the dock, which at least this time we didn’t😀.

Navionics Chart and IPad app

GPS in this case will be from the IPads IOS. As we are stationary this is pretty good and our position is accurately depicted on the chart, soundings are also accurate, I can connect this app to NMEA over WiFi and have managed to display depth and get it to use the real time GPS position but the functionality is quite limited compared with TimeZero, we have found it’s also a little unreliable.

In our opinion one of the biggest drawbacks of Navionics (and Lighthouse) is the overly simplified presentation of their vector charts, which have had nearly 90% of the details you’d find on a paper chart removed. Just compare these with the more detailed raster chart shown below!

TimeZero IBoat IPad app

This app has by far the best user interface and features including advanced NMEA data and weather integration. And its chart packages include both raster and vector charts for most regions that are covered. The GPS will be from the boats sensor.

Unfortunately the vector chart layer is misaligned or incorrectly georeferenced putting the boat around 50 meters away from where we actually are.

But switching to the Raster Layer we are correctly positioned. The detail here is what you would expect to have in a harbour like this.

You can see the clear visualisation of our boats NMEA data and the tide in the customisable slide out panel giving all the information you need when entering a harbour.

Sadly we are seriously lacking confidence in the vector charts. The above is just one of many examples we have had to raise support tickets for: Sometimes the errors get fixed and sometimes they don’t.

If you do use the Raster Charts in Timezero you need to use caution! We are just planning a crossing to Nova Scotia and notice that the chart for one of the potential arrival harbours (Louisbourg) has soundings in Feet whereas the others are in Meters!

ISailor IPad app

Like the Timezero product, this app has NMEA data integration and is rich with features. However we find that the user interface is far too busy, the font sizes are too small and the information is spread across multiple screens. The bigger issue as already mentioned: It’s lacking support so could have a very limited life. But the chart library, when you can access it is extensive.

This chart is perhaps the most accurate and clean depiction of the harbour. We are positioned correctly and the soundings look very accurate.

C-Map iPad app

We use this app to visualise the C-Map global chart library but it does also work as a basic chart plotter. Sadly though it has no NMEA integration, limited chart download capabilities and the least intuitive user interface: Touching the display anywhere triggers the start of creating a route, so you can imagine what happens if it’s raining!

There is also a very dangerous power saving setting in the app to reduce the sampling of the GPS. Why would anyone want to reduce the accuracy and increase the latency of their position?

The quality of the chart is what you would expect from C-Map: It’s a good representation of the harbour and accurate soundings.

In Conclusion

While the various tech companies in this space continue to buy bits of each other, the market situation is unlikely to change in the short term. Our approach and advice is to never rely on a single source of information, or a single device to view that information. It’s also very important to continually assess and evaluate what is happening to a product you are using.

We do however need to be able to trust what our chartplotters tell us, despite the fact that most (rather absurd) displays a “not to be used for navigation” warning when they start up… errrr!! What else did we buy this thing for?

We believe that anyone who claims paper charts, taking bearings, and using leading lines and other traditional navigational aids are safer or more reliable than GPS has likely never sailed into some of the harbors we’ve entered. In thick fog, on a moonless night, with channel markers removed for the winter – then there’s no better option than following a track on a plotter. Add a dopler radar layer and it gets even better.

We could go on about the frustrating “night mode” on most of these devices, but I’ll save that rant for another time. However, here’s one example: on the Axiom Lighthouse display, night mode turns the sea black—and the default route color is also black. You can change the route colour, but can you change the default? No.

Please leave a comment, or send us a message. We would love to hear your views on this topic.