Running aground has to be near the top in the pantheon of nightmare scenarios for yacht captains. Being at the helm when the boat is damaged and inducing the guests to spill their drinks is bad enough. But the mauling to the skipper’s reputation can be even worse. Careers have been fatally holed below the waterline by less.

And yet we are in the grip of a growing trend for explorer yachts and holidays off the beaten track. Every yard building yachts from 20 metres up is urging us to stop quaffing vintage Krug on the Côte d’Azur and go adventuring. And as more owners follow the call, their crews have to grapple with the fringes of our watery world. In more remote areas there is almost no chart detail at all when you inspect the Electronic Chart Display and Information System (ECDIS), and in many others, the scant survey data available dates back more than a hundred years. Not everyone understands what they’re looking at.

“Many yacht guys aren’t commercially trained,” says Steve Monk with a sigh. He is an ex-Royal Navy navigator and now trains yacht crews in the finer points of navigational safety with Da Gama Maritime. “They look at the ECDIS and see a computer with the latest chart. They assume that all the information around them is top-notch. They mistakenly think that an up-to-date chart means it was surveyed yesterday.”

He tells the story of a yacht that grounded off Madagascar. “It was in an area where, if they’d bothered to look at the chart and interrogate it, there was no known datum and the survey data was just ancient,” Monk says. “The paper chart pretty much