That GPS unit that you have learned to depend on may experience difficulties starting on Saturday, April 6. Some GPS units may not receive location data.

The issue is how the GPS unit handles dates. The GPS navigation message stores dates by weeks in a 1,024-week cycle, which is 19 years 36 weeks. GPS week zero started on Jan. 6, 1980, and rolled over on Aug. 21, 1999. After resetting to zero, it rolls over again 18 seconds before midnight on April 6.

The time reset can result in the wrong information on the GPS clock if a receiver doesn’t interpret the week number as the correct date, which may result in position errors on April 6 or a later date.

A Coast Guard bulletin said not all GPS devices will be able to “correctly handle the April 6, 2019, Week Number rollover.” Older GPS receivers — 10 years and older — or those that have had no firmware updates are the most likely to be affected.

It’s best to be safe and check with your GPS manufacturer. Furuno, which experienced the rollover on March 17, has a list of affected units, as does Koden.

Out of Norway today, Navico, the parent company of Lowrance, Simrad and B&G, announced that its products would not experience any setbacks.

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Michael Crowley is the former Boats & Gear editor for National Fisherman.

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