Former priest John Geoghan ``hid behind his collar'' and his position in the church to prey on young boys, Judge Sandra Hamlin said in announcing the sentence.
She detailed Geoghan's admissions of molesting other children and psychological evaluations citing his lack of concern for his victims and his tendency to blame them for his acts as evidence he was not a candidate for rehabilitation.
Under the sentence, Geoghan could be eligible for parole in six years. The judge ordered strict monitoring after any later release.
Geoghan, 66, was convicted last month of indecent assault and battery for fondling the boy in 1991 at a community swimming pool. The victim had testified that he was trying to teach himself how to dive when Geoghan, who had been coaching him verbally, reached inside his swimming trunks and squeezed his buttocks.
Since 1995, more than 130 people have claimed Geoghan fondled or raped them during the three decades he served in Boston-area parishes. The trial was the first of three criminal cases against Geoghan. He also is named in more than 80 civil suits.
The second trial, which was to have started Wednesday, is delayed while the judge hears arguments on whether the statute of limitations for the alleged crime has expired.
The allegations against Geoghan and questions of how much church officials knew have created a scandal for the church and led to major changes in how the Archdiocese of Boston deals with allegations of abuse.
Last month, Cardinal Bernard Law ordered that church officials report all accusations of sexual abuse against minors, including past allegations. Law has since given prosecutors the names of more than 80 active and former priests accused of abuse during the last four decades. Nine active priests have been suspended.
The archdiocese also has been criticized over documents showing that church officials knew of allegations against Geoghan years ago but continued to move him from parish to parish.
During Geoghan's sentencing Thursday, the victim, now a 20-year-old college junior, told the court he felt ``nauseous'' and that he was angered by the ``emotionless'' face Geoghan showed at the trial.
``I think as much time away from the outside world as possible will do him so good,'' he said.
Assistant District Attorney Lynn Rooney requested the maximum sentence for Geoghan, calling the former priest ``a predatory pedophile.''
Geoghan didn't testify at his trial or at his sentencing, and no one but his lawyer spoke on his behalf.
Defense attorney Geoffrey Packard on Thursday asked the judge to sentence Geoghan to probation, saying he was a good priest and neighbor. He asked the judge not to go outside the sentencing guidelines just because Geoghan ``is the flashpoint for the issue that has shaken the foundation of the Archdiocese of Boston.''
After the hearing, Packard said he was concerned about Geoghan's safety and his state of mind.
``I think he's stunned,'' the attorney said. ``He's just been sent to state prison and he's 66 years old. I am afraid for him.''