In a case that has taken over 18 years to come to trial, former child psychotherapist Leonide Kameneff, 76, and three of his crew/staff are accused of rape and sexual abuse by nine former pupils.
Established in 1969, the boat school hosted more than 400 French pupils over three decades on trips around the Mediterranean and across the Atlantic.
Typically aged 11 or 12, the children spent periods of a few months to up to two years on journeys that were supposed to provide them with an alternative education while allowing the individuals to blossom and develop self-reliance.
In reality, according to the nine plaintiffs, some of them were subjected to repeated abuse at the hands of the staff in an environment from which there was no escape and in which Kameneff played the role of controlling guru.
"We were the victims of a man who wanted to act out a dream and used us like his playthings," one plaintiff, Marie Rigod, told AFP.
Kameneff denies the charges and claims it is an era and a philosophy that is being put on trial, 18 years after the first allegations were registered with the authorities.
"Society has changed enormously," Kameneff said. "Things that appeared normal at the time, as educational, are today regarded with suspicion."
Kameneff faces a prison sentence of up to 20 years if convicted in a trial that is taking place in a juvenile court because one of the accused was 17 at the time he is alleged to have abused other minors on the boat.
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The man, now 39, is also one of the plaintiffs having alleged that he was himself raped on board the boat.
In total more than 30 complaints were registered about the conduct of staff on the boat, but a number of them could not be pursued because they were filed too long after the alleged abuse took place.
The trial is also expected to hear evidence from former pupils who have only happy memories of their time on board the boat school.