The attack was alleged to have taken place while the woman slept on a yacht at Dunstaffnage Marina
A student found guilty of indecent assault has had his conviction quashed after a sheriff repeatedly referred to his "victim" during the trial.
Giovanni Passamonti had denied attacking the woman while she slept on board a yacht at Dunstaffnage Marina, near Oban, in October 2012.
He was found guilty and put on the sex offenders' register.
His lawyers argued on appeal that his trial was prejudiced by references to a "victim" before a verdict was returned.
The woman should have been referred to as the complainer.
Mr Passamonti, 22, of Edinburgh, was originally convicted after a trial last year and ordered to carry out 300 hours of unpaid work.
Sheriff Douglas Small told him at the time it was "an extremely serious offence" which could well have ended up with a custodial sentence.
Judges at the Court of Criminal Appeal on Thursday were told that the Crown was not opposing the appeal against conviction based on two "errors" by the sheriff.
Defence lawyers pointed out the sheriff had directed the jury not to allow sympathy to play a part in their decision-making.
But they maintained that the repeated reference to "the victim" was likely to have led the jury not only to take a sympathetic view of the woman, but also to conclude that an offence had been committed.
The defence also said the sheriff erred in law in failing to give the jury directions over how to deal with a mixed statement - one which partly tends to clear the accused and partly incriminates.
Mr Passamonti was not in court to hear the successful outcome of the legal challenge.
