Check your GPS / AIS devices. Some of them failed on Jan 2, 2022 due to the "GPS Rollover" bug

Scott SV Tengah

Garulfo, a fellow A54 informed us that their Furuno FA-50 AIS transceiver stopped transmitting at midnight on Jan 2, 2022 GMT. By chance, they use the output from the AIS unit (AIVDO NMEA sentence) to feed their wifi gateway and noticed that they lost position at that precise time.

I checked my own equipment and have the same issue. My FA-50 AIS transceiver, but GP-150 GPS Navigator and also my Navnet V2 are all subject to the "GPS rollover" issue. I happened to be on a Catana 50 last night and all of their GPS equipment had the same issue.

See attached.

It is not a Furuno specific problem, but rather related to the week counter system on the GPS system, which is only 10 binary digits. That means at 1024, it goes back to zero. Unless the manufacturer anticipates this, your device will either lose position, show a date 19.7 years in the past or both. 

For Furuno, many of the devices can be updated by the dealer. Unfortunately for us, we're in the remote Tuamotus and have no intention of being near a dealer for the next 6 months. 

If you want to check your AIS, ask a neighbor boat whether they can see you. If you're a bit more technically inclined, you can check the NMEA output and put your AIVDO sentence through this decoder. If it shows invalid position value, then your AIS is no longer transmitting your position. It will likely still receive, however.

Thanks to Garulfo for pointing out this problem, otherwise I would have blissfully been unaware that I wasn't transmitting. I am guessing many AIS users will be in the same position.

2007 A54 #69
SV Tengah

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