No doubt about it, AIS is one of most valuable technological advances we’ve seen in recent years. It’s enormously helpful to see data about what a vessel is, how fast it’s going and the direction and speed in which it is travelling on a chartplotter. And if you fit a Class B transponder yourself, your yacht should show on a ship’s bridge as clearly as any supertanker.

But as with any navigation equipment, it only works if someone’s watching it and doing something with the information. AIS doesn’t magically improve poor watchkeeping routines, as has been illustrated on the Global Ocean Race.

As the six boats taking part in the two-handed round the world race raced from Mallorca to the Straits of Gibraltar this week, Miranda Merron and Halvard Mabire reported two very close calls with ships. In one incident they had to get out of the way of a ship that passed 200m from their transom in the middle of the night, ‘despite AIS, carried by ships and us,’ reports Miranda.

Two nights later, they had an even closer call. ‘A trawler made a huge course alteration at the last minute and suddenly we were heading straight for them surfing downwind in 25 knots of breeze in the black night,’ Miranda again reported.

‘The only way to avoid a collision was to wipe Campagne de France out, laying the poor boat on her side with spinnaker flogging wildly. I tried and eventually managed to sock it. Luckily it is bullet-proof (so far). We don’t think the fishing boat even saw us, despite us lighting the sails, and watching them pass metres away while we were on our side.’

I suspect Miranda and Halvard have other things to worry about as they race on the first leg to Cape Town, but one other good thing about AIS displayed a chartplotter/radar is if you can show a track and take a screen grab when forced to take some emergency avoiding action, you could make one of those ‘0800 How’s My Driving?’ reports …