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How to Get Weather Data on Your Boat

Garmin’s BlueChart Mobile app

Weather Where You Want

Getting the good data where you can see it means better boating decisions.

I’ll never forget it. Editor-in-Chief George Sass Jr. and I were taking a brand-new center console from Liberty Landing Marina in Jersey City up to Rowayton, Connecticut, one summer Friday afternoon. A quick run to be sure, and all the quicker for the 250-horsepower Yamaha pushing that cool new boat. But as we came into Long Island Sound and then proceeded toward Greenwich, a nasty-looking cloud bank showed itself over the Connecticut shoreline and we had to quicken the pace even more.

Every mariner has seen clouds like this, where you can make out the haze of precipitation hanging beneath an already-low ceiling. It’s not if you’re going to get wet, the question is more how much? And when? But I was cool with it. You see, my eyes played a trick on me, and I thought the cloud bank was over the land, moving parallel to us, almost racing us to our destination. And I liked our chances in that speedy boat. It didn’t occur to me that the squall line was moving across the shoreline—not until those huge raindrops began to pelt the water around us with a quickening pace. And then we felt that cool rush of air and the wind really kicked up and the lightning started flashing white and purple, as it does when it seems really, really close.

Obviously avoiding having too many of these sorts of anecdotes to tell in a lifetime is the goal. And it would seem that since many of us feel as updated as we do these days through smartphone use and connectivity, good weather data should be an admirable addition to our steady diet of news and information. But if you’re like me, you feel like you should get everything on one screen—at the helm. Fortunately for us, the developers of helm electronics systems understand this and have done a good job of adding weather functionality. But the way the data gets there is interesting—so interesting that some of the data isn’t quite there yet, but is still good to know about.

The appeal of the SiriusXM satellite weather system is obvious. It’s an add-on to your boat’s electronic system, and it links directly to your MFD. It overlays weather data directly on the charts, including NEXRAD (Next-Generation Radar)  showing precipitation and satellite cloud imagery, and also gives you five-day forecasts, lightning-strike data, buoy reports including wind and wave-height, and sea-surface temperatures. Furuno, Raymarine, and Navico, including the brands Simrad, Lowrance, and B&G, offer blackbox SiriusXM satellite receiver/antenna packages (audio splitter included), available now at street prices around $600. Monthly fees for the satellite weather system start at $12.99 for Marine Inland weather, and go up to the Marine Offshore service, for $54.99 per month.

Garmin also has a SiriusXM system, but instead of using the original Sirius satellites its receiver uses XM’s with XM WX Satellite Weather data and analysis provided by WxWorx. The SkyWatch service starts at $9.99 per month, and tops out at the Master Mariner level at $49.99 per month. Users need to consider how they use their boats to determine which service level is right for their needs for any satellite service. SiriusXM’s satellites purportedly cover all of the U.S. and up to 200 miles offshore.

Garmin weather data

Garmin also offers another way to access weather data: The BlueChart Mobile app. Available for iPad and iPhone for free through the iTunes Store, these apps offer for-purchase charts but they also offer a fairly solid amount of free weather data, including temperatures, dew points, wind direction and speed, radar, and cloud cover, buoy reports, marine-zone forecasts for the U.S., Canada, and Europe and land-zone forecasts for the U.S. and Canada, surface wind forecast grids, sea-surface temperatures, and forecasts of surface pressure and sea state. Of course, if that’s not enough, in-app upgrades for $4.99 per month can give you StormWatch watches, warnings, and advisories, NEXRAD precipitation imagery, lightning information, and infrared cloud imagery. But here’s the coolest part: The user can download the data to an iPhone or iPad, and overlay it on the in-app chart, but then, if the Garmin MFD Wi-Fi is set up to connect to that mobile device, the weather data will upload and overlay on the chart on the helm display.

And that’s similar to how Furuno can display free worldwide weather data on the TZTouch and TZTouch2, only without the intermediary app. “With the current system right now in TZTouch and TZTouch 2, all the NOAA GRIB (Gridded Binary) files are saved at our Navcenter Intranet,” says Eric Kunz, senior product manager at Furuno USA. “And when any of the MFDs poll that for information it just sends up the latest data that’s available. And most of the information is all forecasted. It’s the same thing you’d pull off Sirius a couple of times a day. Right now it’s an on-demand service, so you have to query the server to get the latest data. If you leave TZTouch or TZTouch2 continually connected to the Internet, there’s no reason we couldn’t push that data to you anywhere. Even if you’re away from the dock and you don’t have a Wi-Fi connection, it could link up to your phone anytime you wanted to as well. 4G coverage is getting better all over the place.”

There are some differences in the data that’s offered. “At this time we don’t offer the cloud coverage like you see on the news, but that’s what your radar does very well!” Kunz says. “For fishing, we deliver chlorophyll data and modeled altimetry data as well, which is arguably more important than sea-surface temperature. Of course sea-surface temperature is nice but it’s not the whole story, and a lot of time the sea-surface temperature is not shown because of cloud coverage.”


One thing you should know: Here in the U.S., we’re fairly spoiled with the kind of weather data we get. “In the States we have got used to NOAA providing high resolution data over the years,” says David Young, managing director of Theyr Ltd., a UK-based weather-data service. “For a long time, we never had that anywhere else or at least not easily accessible. Several years ago, we put an emphasis on developing a high-resolution model for Europe. So we covered the whole of Europe and the Atlantic with 0.1-degree resolution, and we’ve since expanded that to offer a global 0.1-degree resolution output. So for the American market we now push that 0.1-degree out from three days, out to six days and increase the time step to hourly.” 

Theyr began developing its system for offshore racing sailors, so they built it to download the data to allow analysis. “We’ve refined the data to ensure maximum compression for transfer,” Young says. “That’s significant when you’re sailing. Even if you’re just on a cellular connection, charges can add up. But if you’re using the likes of satellite connections it can get expensive. So we’ve done a lot of work on that. Today you can download directly to our devices, or use your mobile telephone as a modem, even if it’s just at the marina, you can download the data before you go out. That’s the beauty of our GRIBview app, our desktop and mobile applications are all offline. So once you download that data you can view it when you need it and where you need it.”

Theyr’s GRIBview iPad app

While it is not integrated into helm MFDs, the Theyr app, in addition to the Garmin and Furuno systems, show how smart data management may bode well for good management of critical weather information in the future. Maybe someday it will get so simple to acquire the latest data and review it, that I’ll actually remember to look at it before I set out!

This article originally appeared in the February 2016 issue of Power & Motoryacht magazine.