A superyacht sank off the coast of Sicily during a sudden storm overnight on August 19. There were 22 people on board the Bayesian, including British tech tycoon Mike Lynch and his wife, who own the yacht. The Italian coastguard rescued her and 14 others; one passenger died and six are missing, including Mr Lynch and his teenage daughter. Witnesses say the huge 56-metre-long ship sank in a matter of minutes.
The Bayesian appears to have been the victim of extreme weather. But since it sank at night, it’s not yet clear what exactly is responsible. One possible culprit is a storm waterspout, a seasonal phenomenon that occurs at sea, usually accompanied by strong winds and waves. Waterspouts are derived from powerful storms, several of which have devastated Italy this summer. How dangerous are they, after all?
Waterspouts fall into two categories: thunderstorms and tornadic ones. Both are columns of spray and mist that connect clouds in the sky to the ocean. Thunderstorms are weak, brief and form from the ocean surface, with warm air rising skyward. The tornadic waterspout, on the other hand, is actually a tornado. Most tornadoes form from severe storms called supercells, during which streams of warm air rise upward while denser cold air falls downward. When those streams come into contact with differences in wind strength at different altitudes, they form a violently rotating vertical column that eventually touches the ground—or in this case, the ocean.
Stormy waterspouts can be very dangerous – but if one is indeed responsible for sinking the Bayesian, it would be very unusual. If the column of air is strong enough, it can push the boat’s mast so far that the boat can no longer upright itself. According to witnesses interviewed by Reuters, the wind caused the yacht’s mast to lay flat against the water. Boat designers and owners like very tall masts, partly because they can make the ship faster and partly because of prestige – at 72 metres, the Bayesian had one of the world’s tallest aluminium masts. This means that the yachts often carry a lot of weight, making them less stable. But such vessels are designed so that they do not sink even if their mast goes under water; their keel must provide a counter-weight that can upright the boat.
This suggests that there were other problems too – possibly portholes, hatches and the like had been left open. The Bayesian also had a retractable keel, allowing it to berth in shallow harbours: if this had been dragged during a storm, it would have reduced the leverage exerted against the force of the wind on the hull, masts and rigging. And the enormous updraft of a waterspout creates an equally catastrophic downdraft: which would have pinned the boat in its upside-down position, flooding it with water.
Given the growing consensus among scientists that extreme weather events such as storms and floods are influenced by climate change, many observers may wonder whether such rare tragedies might become more common. Although the number of reported waterspouts in the Mediterranean has increased in recent decades, researchers believe this is largely due to better monitoring. There is not enough data to tell for sure, but it seems there has been no significant increase since 2006, says Tomas Pusic, a researcher at the European Severe Storms Laboratory.
But it doesn’t take a waterspout to make a severe storm dangerous. Oceans around the world are warming significantly during 2023 and 2024. This could make storms more powerful and cause other worrying effects. A “downburst,” in which heavy, wet air falls on the ocean surface and creates strong surface winds that propagate horizontally, is another possible Bayesian explanation for the sinking. Maritime inspectors may be able to figure out what really happened to the ship. Experienced sailors already know how unpredictable Mediterranean weather can be. Monday’s tragedy is a harsh reminder.
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