Apps for Sailors: NWS Broadcasts Made Easy

A new app, HF Weather Fax Marine Radio Facsimile Decoder brings traditional offshore weather information to smartphones and tablets.
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A new app, HF Weather Fax Marine Radio Facsimile Decoder brings traditional offshore weather information to smartphones and tablets.
 A screenshot showing how the app displays weather faxes

A screenshot showing how the app displays weather faxes

A new app, HF Weather Fax Marine Radio Facsimile Decoder brings traditional offshore weather information to smartphones and tablets. The app displays marine weather radio fax transmissions on your Apple iOS or Android device without a dedicated fax receiver or an expensive modem. This app is brilliant, as it significantly simplifies the delivery of information from the national weather service (NWS) and displays it on your device automatically.

Traditional NWS weather broadcasts arrive via fax from locations worldwide, displaying satellite images, sea state analysis, surface forecasts, wind/wave analysis and forecasts, and wave period/swell. Transmissions are scheduled throughout the day with periods of inactivity.

With this app, the received weather fax is automatically displayed on your device’s screen, and can be played through your audio system. Black Cat Systems claims you can pick up adequate audio reception by positioning your device near external speakers, but I’ve found that background noise from sailing makes this impractical. Instead, I connect the radio audio output to my tablet’s microphone-in port using a dedicated audio cable. Black Cat Systems’s website includes a list of recommended cables as well as DIY cable wiring diagrams for this purpose.

This app does exactly what it needs to do and it works well. The interface is intuitive, with minimal options. Upon opening the app, the receiving fax broadcast automatically displays on the screen. Click “tune” to adjust your radio frequency and receive the best signal; click “start/stop” to pause reception. Use the “auto” function to save images after each transmission or “save” to manually select which broadcasts to save. Click on “schedules” to view the NWS weather fax schedule.

Best practice is to connect your device to the marine SSB using the attenuated microphone-in cable, tune the radio 1.9 Khz below the published frequency, launch the app and select “auto.” Then simply leave the app running and start receiving the transmissions; view the images later at a convenient time.

Although fit for purpose, I’d like to see a few enhancements. First, I’d like saved images to be available through the device’s camera roll, so they can be viewed and emailed outside the app. Second, I’d like the images to adjust to landscape mode on the iPad. Finally, I’d like to be able to bookmark nearby stations in “schedule” so I can find relevant broadcast times without having to manually page through.

If you are sailing offshore or are a marine SSB/ham radio enthusiast, this app is an obvious addition to your weather forecasting toolkit. I give it 4 stars, with the anticipation that future enhancements will improve its use.

* * * * *

Black Cat Systems,, $2.99

Application architect, software developer and sailor Donald McLennan reviews apps for SAIL while cruising the waters of Southern California aboard his Tartan 3500 with his wife, Laura, and daughters, Alexandra and Elizabeth. Each month, Don tests a handful of new apps and brings you his favorite. If there’s an app you’d like to see reviewed in 2014, let us know, with an email to



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