INVESTIGATORS sent a robot probe into the waters of the Atlantic yesterday to hunt for clues into the sudden death of Edouard Michelin, 42, the billionaire boss of the world’s biggest tyre company.

His death while fishing in the treacherous waters off Cape Finisterre was a blow to the French institution that was founded by his great-grandfather 140 years ago, and triggered speculation as to who would lead the company.

M Michelin’s body was found floating among lobster pots last Friday. Yesterday a Navy mine-hunter found his 24ft (7m) fishing boat on the seafloor, 150ft down.

A Navy robot camera scouring the site near the island of Sein could find no sign of the body of Guillaume Normant, a friend and experienced fisherman who had taken the tycoon out in search of sea bass.

The accident saddened France because the company, also renowned for its maps and food guides, has been a Gallic institution since the earliest days of motoring, and it remains one of the last great family businesses.

The company reassured its 130,000 workers that its future was secure under Michel Rollier, 61, who was co-chairman. But doubts continued about the succession because M Rollier is only a distant descendant of the founder of the company, also called Edouard Michelin.

The company has always been run by his direct male descendants, and no Michelin appeared qualified to take over. M Michelin’s six sons and daughters are too young, and only one of his brothers works for the company, in a middle-level job. Questions were raised as to whether his brothers Benoit or Damien could help to run the company. Another brother is a priest and his sister a nun.

Police do not suspect foul play but a mystery remained over the sudden death of one of France’s richest men. M Normant was a local professional with long experience in the Atlantic. Maritime officials said that conditions were acceptable when the fishing boat disappeared on Friday, although fog had cut visibility to 200 yards (180m).

But Robert Bougueon, the head of a local fisherman’s association, quoted M Normant’s wife as saying that M Michelin had persuaded her husband to take the boat out against his better judgment. “He didn’t know how to say no,” M Bougueon said.

Jean-Marie Figue, a spokesman for the maritime authorities, said: “It is a dangerous area where only professionals can fish. There are rocks, currents — it’s a real whirlpool.

President Chirac said that the French economy was in mourning for a great businessman. Workers at Michelin’s base at Clermont-Ferrand, where 17,000 people work, queued to record their condolences for the man who had modernised the company during his seven-year tenure.

M Michelin had earned the affection of the workforce despite a rocky start in 1999, when François Michelin, his father, handed power to him. That year Edouard enraged the unions and public opinion by announcing plans to cut 10 per cent of the company’s European workforce at the same time as he announced an increase in earnings. The Socialist Government of the time then enacted a law making it harder for companies to dismiss workers. He said afterwards that he had learnt a lesson from the episode.

M Michelin, who lived modestly in keeping with his family tradition, is credited with introducing openness and modern methods into a company that was notoriously secretive.

M Michelin, who had once worked as a messenger for the company during school holidays, re-established its presence as the main supplier for Formula One racing.

Last year it earned £520 million profit, although Michelin had said this month that harder times lay ahead.

M Michelin’s father, 79, still has an office at the company, but he was said to be unable to consider returning to management because of poor health.

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