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Voyaging electronics

Jun 29, 2018

How voyagers upgraded their electronics suite

Rebecca and Patrick Childress’ Valiant 40, Brick House, at sea.

Rebecca and Patrick Childress’ Valiant 40, Brick House, at sea.

Rebecca Childress

We are sailing into the tremendous expanse of the Indian Ocean from Malaysia to the stormy South African coast and on around the southern tip to Cape Town aboard our Valiant 40, Brick House. There are long stretches where pleasant weather can, in a moment, change to be outright dangerous. For this reason, we decided to add a new selection of marine electronics to our vessel, both hardware and software.

For more than 11 years, our SSB radio, Pactor modem and laptop supplied us basic weather information, utilizing grib files when the dice were in our favor and propagation was workable. Just like MP3 players have replaced cassette tape players, our antiquated systems and communication techniques have been left behind, replaced with more reliable tools and omnipresent satellite communications.

Our first order of business was to choose our software preferences. I didn’t want to choose hardware first and then be locked in to suboptimal applications. After years of testing various navigation and weather packages on laptops and other devices, we chose the Navionics Boating applications for backup navigation, and PredictWind Offshore for weather data.

Tablets like the iPad can display navigation data like this Navionics chart.

Courtesy Navionics

Navionics charts
Navionics, the charting we have used on our Raymarine chartplotter for more than 11 years, has never let us down. We have supplemented it with paper charts and Google Earth images, but the information Navionics provides makes major leaps every year, and supplements are hardly needed anymore. Navionics on our devices and laptop, as well as the chartplotter, can sync waypoints and tracks and be updated wirelessly.

We do use Jeppesen C-MAP as well, mostly as a way to compare the data. This is like having two votes as to where that reef is located instead of just one. If they both agree, it’s obviously a well-documented reef. If they disagree, we will certainly give it a wider berth than we normally would and try to get an up-close Google Earth image of that reef too.

Navionics Community Edits are like having a built-in cruising guide. When any user has found an uncharted rock, a good anchorage or even a nice seaside restaurant, they can save the waypoint with a description and automatically upload it to Navionics, where it is then visible to everyone. Navionics also incorporates modern chartplotters’ sonar mapping data that can be automatically uploaded and processed within about a week, allowing everyone to utilize corrected depth soundings to navigate into previously uncharted areas. SonarChart offers a huge advantage when cruising less-traveled areas where accurate charting is sparse. I only need to remember to register and update the Navionics card before heading out to sea in order to have the most current updates, including Community Edits and SonarChart. Navionics gets better and better every year with the help of cruisers that are on the sea providing real-time data!

Digital Yacht’s WindSense turns a tablet into a wireless wind display.

Courtesy Digital Yacht

Weather info
PredictWind is the premier provider of weather models for sailors — over Internet, satellite or SSB. PredictWind is the only affordable software we have found that works offshore, via satellite or SSB, as well as when we have an Internet connection. Just as important, it also offers the European Center for Medium-Range Weather Forecasting (ECMWF) in addition to the Global Forecast System (GFS) run by the U.S. National Weather Service. Few competitors of PredictWind offer the ECMWF forecast because it costs over $200,000 to have access to it. ECMWF is what professional racers and luxury boat captains use, something not previously accessible to penny-pinching cruisers. PredictWind also has two unique forecast models of their own, which surprisingly are often more accurate than the ECMWF and GFS models.

It also has three or four ocean current models that are extremely accurate and very important in the Indian Ocean. There are certainly many weather information services that offer GFS and even ECMWF data and current data — and with sexy, pretty displays — but these almost always require an Internet connection. PredictWind provides both over satellite or SSB at sea when others simply cannot.

We chose PredictWind Offshore because of its four weather models and because it provides a seamless way to retrieve all this weather information at sea. We can compare the four models, and if they all agree we can be pretty sure of what lies ahead. If there are huge differences, it will be one of those unpredictable passages that deprive us of sleep. We can use the weather routing feature to compare the four models and determine what might be the best route and the best departure time for the specific sailing characteristics of our boat, Brick House.

AISView for Android from Digital Yacht allows you to view AIS info on a Google Maps background.

Courtesy Digital Yacht

GFS and ECMWF actually use different methodologies for predicting atmospheric conditions. GFS, a hydrostatic model, uses pressure and vertical coordinates, making generalizations about topography. It does poorly at higher resolutions where topography will have impact in the forecast. The ECMWF, a nonhydrostatic model, uses altitude and accounts for topographic effects on weather systems. This report is produced twice a day down to 9-km resolution as opposed to GFS’ 27 km. ECMWF has also been the model to most accurately predict and track movements of hurricanes. The two other models that PredictWind uses are proprietary. In observing these models, they have proven to be invaluable additions to the picture, getting things uncannily precise as to when the wind or rain will be the strongest — often to the exact hour.

Friends ask why we spend money on weather when free reports are available on the Internet, and the weather forecasts are always wrong anyway. The answer lies in the question. To get weather that’s right, you have to pay for it — especially if you want it accessible at sea. Those friends aren’t seeing the ECMWF if they are using free programs, and they aren’t sailing offshore, away from Internet. PredictWind Offshore is worth every penny for a passagemaking cruiser.

PredictWind offers multiple packages. We have chosen the Professional version for this year since the various models of ocean currents are critical for us rounding Sri Lanka, crossing the strong currents at the equator and rounding South Africa. It is a nice bonus to have even finer resolution of grib files. But if currents were not a big factor, I think their Standard version at $249 per year is a perfect compromise and worth every penny. While we don’t necessarily follow their weather routing advice, we do use it as a quick tool to detect extreme weather and to see if any large detours are important. But we love the Departure Planning tool. It allows us to compare what our passage is likely to be like leaving at different times on different days. This last departure was a hurried one prompted by PredictWind Offshore, which helped us catch the last of a perfect wind and stay right on the back edge of helpful weather for days, while those behind us motored the whole way. It saves us hours over doing our own amateur meteorological predictions.

The Bad Elf GPS Pro is a Bluetooth-equipped GPS receiver that can supply GPS data to tablets and smartphones.

Courtesy Bad Elf

Making a tablet choice
Once we knew what software we wanted to use, our first hardware purchase was a 9.7-inch iPad to be used as a backup and planning platform. The iPad uses less energy than the personal computer and is more mobile around the boat. There are two versions of iPads that an ocean-crossing navigator must understand: “Wi-Fi only” and cellular versions. Since I wouldn’t get cellular service at sea, I felt safe buying the “Wi-Fi only” version. That was a mistake.

After I installed Navionics Boating onto the iPad along with charts specific to my current area, I noticed something horrifying. There was no boat icon on the screen depicting my location! My iPad had no idea where I was. Apple support confirmed that my brand new Wi-Fi iPad didn’t have GPS! Only cellular versions of iPads have GPS chips; mine had a locator service called iBeacons, which is not hardware but simply a brand name created by Apple. When an iPad is near to an iBeacon, which is a strategically placed transmitter purchased by businesses, airports or other organizations, the iPad can receive promotions or information from these entities. These iBeacons also feature micro-location georeferencing providing GPS positions. Regular GPS signals have trouble penetrating the steel and glass of buildings, but an iPhone/iPad with the iBeacon feature can receive its GPS position this way. The other way that Wi-Fi-only iOS devices like my iPad are able to determine location is through Wi-Fi triangulation. A cached database of Mac addresses/physical locations exists locally on the iOS device and, based on the Mac ID and signal strength of a specific set of routers, one’s location can be determined. In either case, if you go offshore there is no more position information on “Wi-Fi only” iPads. It is not that a SIM chip or cellular service has anything to do with GPS, it’s just a marketing decision — or an engineering problem due to the small spaces inside of these devices — that made Apple not include a GPS chip in their “WiFi only” versions. With no GPS chip, you get no GPS position at all when offshore. That’s why there was no red boat depicting my location in Navionics.

The cellular version of an iPad has an actual GPS chip; specifically, an “assisted” GPS (aGPS) along with a GLONASS chip (the Russian version of GPS). This is a real GPS chip relying on satellites but “assisted” for quicker fix acquisition from receivers/rebroadcasters on cellphone towers. These rebroadcasters send their collected data from the satellites to all surrounding receivers for faster location acquisition and less processing power for the receivers.

The Bad Elf GPS with lightning connector plugs into the lightning slot on iPads.

Courtesy Bad Elf

With no towers, one must wait for the satellites to be tracked, which can take two to 10 minutes depending on how well and how long ago the device “sees” the sky, and the characteristics of that GPS chip. This is similar in Android devices. If there is no cell tower, like at sea, it simply uses the satellites above, assuming it has the standalone GPS to feed it the signal. Some chips are faster and more accurate than others.

It’s difficult to determine the true accuracy and quality of a GPS when purchasing a unit, since you are often near cellular towers when in stores. Although there are GPS accuracy applications that, if used properly, can test the accuracy of the GPS, you can’t always install these in the store before you purchase. Be sure to turn off cellular completely before testing because, remember, the cellular will suggest it is more accurate than it really is offshore, and you are trying to simulate the effect of having no towers like you would offshore.

The quality, configuration and implementation of aGPS is not standardized. Your device may act as a standalone or may only work if assistance is present. Some models only allow use of aGPS for 911 calls and will not be available for applications. You may have a hybrid. Accuracy will range to between 15 and 50 feet, and the quality and longevity of the GPS chip will vary. Chips are often changed between models. It is advisable to use Google to find how each model is working for sea navigation from other sailors. If you find a setting to use satellites only, this is a good indication that it should work at sea.

The more satellite constellations being tracked, the faster and more accurate overall positioning will be. There are many Global Navigation Satellite System (GNSS) constellations. For example, our Samsung Galaxy Tab A tablet tracks GPS, GLONASS and BeiDou (China) satellites.

Digital Yacht’s iAIS product overlays AIS info on the Navionics Boating app.

Courtesy Digital Yacht

Improving positioning
But back to my iPad. Since I could not exchange my new “WiFi only” iPad for a cellular version — and desperately needed GPS while at sea — I investigated and found a few Bluetooth GPS units that my iPad could connect to for a position. Many GPS Bluetooth units will work, but only one company consistently cut through the newest code and updates: the Bad Elf GPS.

The Bad Elf GPS receivers provide reliable high-performance GPS when connected to almost any device that uses the location-based application. While many devices have some form of built-in GPS that work well in coastal cruising areas near towers, some cruisers discover that at times they work intermittently as they sail along. Can you imagine one minute you think you are mid-channel, then your GPS pauses and suddenly jumps to showing you on a reef? The accuracy differs between various GPS chips, and just three to 15 meters can make a big difference — especially in nasty weather entering a pass or navigating in tight quarters. Bad Elf eliminates some of this unreliability with accuracy down to around two meters.

Many sailors navigating with tablets depend on whichever internal GPS came on their device, never giving the internal GPS a second thought. They may not realize that the actual location of the boat on their chart is slightly askew. We hear about boats hitting reefs that are mischarted, but sometimes the device’s GPS position is actually what is mischarted. How many boats have come to grief using tablets with lower quality, lower accuracy or failing internal GPS? Using your eyes and seamanship is always key, but we have these electronics to help us. We need to use them properly and understand their limitations. Best yet is to use a high-quality GPS chartplotter like our Raymarine eS128. But if a cruiser is going to use a hand-held device or laptop for chartplotting, the device should be connected to a reliable GPS like the Bad Elf.

There are two units that Bad Elf recommends for mariners: the Bad Elf GPS Pro or the Bad Elf GPS Pro+.  With either one, navigators can be confident they have the GPS with the greatest accuracy and reliability, and a great backup should the internal chip of their device or chartplotter quit mid-ocean — or, if like me, the wrong iPad is purchased. However, navigators still have to remember that charts are not going to be accurate down to the meter, so even with a near-perfect GPS like the Bad Elf or a high-quality built-in chartplotter, always use your eyes and good sense.

Patrick and Rebecca are currently crossing the Indian Ocean aboard Brick House.

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