How would you react to GPS failure while sailing? James Stevens answers your Questions of Seamanship

GPS failure: a man looking at a GPS on a boat
If the position of your yacht suddenly changed on your chartplotter, how would you react? Credit: Lester McCarthy

GPS failure: What would you do?


Ian runs a highly successful software company. He has recently purchased Free Electron, a custom-made 14m sailing yacht.

He insisted on the very latest electronic systems so the navigation area is more sophisticated than most merchant ships. Ian is very adept at handling this equipment.

He has not taken any navigation courses because he reckons that his instructor will know less than him about the use of modern electronics.

Unsurprisingly, there are no ‘old-fashioned’ paper charts on board.

Ian has also taught himself how to sail and if the boat handling becomes a little difficult in the marina, he arranges for the launch to help with berthing.

A chart of Flamborough Head

Credit: Maxine Heath

He has successfully visited most of the harbours on the South Coast and is now sailing up the East Coast on a circumnavigation of the British Isles.

He is approaching Flamborough Head. The wind is southwesterly Force 5, the visibility about 2 miles and the autopilot is holding a steady course about 6 miles from the land in 22m of water. Suddenly four alarms go off at once.

The position of the yacht on the chartplotter jumps 20 miles on to the land giving a speed of 100 knots.

Alarms are coming from the plotter, the DSC radio, AIS and the autopilot, the latter is now steering straight for the land.

No problem, Ian turns off the instruments, hand steers and opens the navigation app on his phone. It is also giving a position on land.

What has happened and what does he do?

Continues below…

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