Weather information at the helm is rapidly advancing. The old standby — NOAA weather broadcast over VHF — has not been eclipsed, but information provided by satellite weather service and NOAA data files off the Internet provide powerful tools for trip planning and heavy-weather avoidance.
Which of these options is available depends on the equipment that’s on your boat. Most plotters support SiriusXM satellite-radio weather — a merger of two separate companies, now one sharing audio, but still independent entities regarding weather broadcast. Raymarine, Furuno, Lowrance and Simrad all support Sirius weather data. Garmin supports XM. Humminbird, which once supported XM, now does so in legacy plotters, and is currently revamping its weather module.
SiriusXM weather provides real-time radar and 28 different data sets, ranging from sea-surface temperature to wave and weather forecasts. How many of these data sets you access depends on which of them your plotter supports, and which data plan you have. SiriusXM data plans come in four subscription levels, ranging from $12.99 to $59.99 a month.
Simple Sat Service
Satellite weather requires a receiver. Raymarine’s newest, the SR150 ($699.99) provides access to two Sirius data packages, the Marine Coastal ($29.99 a month) or Marine Offshore ($54.99 a month). The weather data displays on its own, windowed alongside other information, or overlaid on the plotter; it’s compatible with A-, C-, E- and G-Series products. The SR150 works with the previous-generation C-Wide, E-Wide, E-Classic and G-Series Raymarine plotters as well.
A powerful aspect of SiriusXM is it is a broadcast of real-time weather, like a movie. And because it’s satellite generated, it works hundreds of miles out to sea and updates constantly. A second source of data, NOAA weather files, requires Internet access. This data, delivered as compact GRIB files, presents a snapshot of conditions, and updates only when you download another one. The advantage is that these files are free. Various suppliers offer their own version of these files, such as Jeppesen’s C-Weather, which is what Standard-Horizon CPN plotters support, offering a five-day weather forecast updated every six hours, wind direction and strength, wave height and direction, ground temperature, humidity and visibility in miles. Not all plotters support GRIB file display.
Simrad plotters support files downloaded from the Internet and uploaded to the plotter via SD card or USB. This makes a powerful planning supplement to the Sirius weather function. “GRIBs are free — that is the real draw,” says Simrad’s global brand manager, Dennis Hogan. “They are geo-referenced so they overlay seamlessly on the chart plotter, and they link to each other automatically, so you can animate a history-to-present loop. These files are superior for planning, when you are in reach of a server.”
For satellite weather access, Simrad’s NS Series multifunction displays support the new WM-3 SiriusXM Satellite Weather & Radio Module ($799) on NSO Offshore, NSE Expert and NSS Sport models. The WM-3 also includes an antenna splitter that allows performance monitoring over the Ethernet to NS series displays interfaced with any onboard sound system.
Two weather-subscription packages are available: The Marine Coastal (Mariner) package includes weather buoy observations and sea-surface temperature, as well as a wind and wave forecast, city forecasts, and current fuel prices. The Marine Offshore (Voyager) package includes the same features, with an enhanced wind- and wave-forecast window of 48 hours.
“We offer most of the SiriusXM data sets,” says Hogan. “We also have new software coming out for NSE and NSS that supports even more.”
Furuno also supports a couple of options, and some things you find nowhere else. The Sirius weather receiver BBWX2 ($800) works with NavNet TZtouch, NavNet 3D and NavNet vx2. Additionally, NavNet TZtouch supports the free Marine Weather Forecast at navcenter.com, which downloads files directly onto the plotter. Select an area, then zoom in to reduce the coverage of the downloaded GRIB files, while increasing the area detail. “It’s delivered in a tiny file that goes graphic on the display,” says Eric Kunz, Furuno’s senior product manager. “You can peel the layers you unpack to and show what you want to see. “
Data layers include wind, waves, atmospheric pressure, clouds, rain, sea-surface temperature and ocean currents, and a couple that are seldom available elsewhere: chlorophyll and altimetry. Chlorophyll identifies nutrient-rich areas of the sea surface that are likely to support an active food chain, from plankton to predators. That’s valuable information when you are hunting predators.
The second data category, altimetry, provides the height of the sea surface above or below mean sea level. Variance in sea-surface height is a function of temperature in the water column. Warm water occupies more space than cooler water, which raises the sea surface. This variance can be measured by satellite and plotted on a chart to indicate water-column temperature. Altimetry indicates water temperature at depth to locate temperature breaks far below the surface, independent of sea-surface temperature, which is affected by cloud cover.
Altimetry data is little utilized and seldom discussed. “The big thing about altimetry,” says Kunz, “is the guys who know about it don’t want to talk. Our engineers don’t want to talk about it because they don’t want to educate the competition. There are anglers on the East Coast who have used it to win major tournaments, and they don’t want to share their edge. Knowledge, in this case, is power.”