Frank Walmsley's rapes of teenagers in his care has been compared to child rapist Robert Burrett's crimes.
Before sentencing him to 22 years' imprisonment, Justice David Gendall drew comparisons between Burrett and Walmsley, who abused children in the Child, Youth and Family home he ran in Oamaru in the 1990s.
Burrett, a former Christchurch school caretaker, was sentenced to 19 years and six months' prison in April for raping, sodomising and performing other sexual acts on a dozen victims, aged five to 12.
Referencing "chilling" statements from Walmsley's victims, the judge said his offending "has had a devastating effect upon them all".
Several victims told the Hight Court at Timaru on Friday they continued to have flashbacks and had turned to drugs to try and block out memories of the abuse.
Justice Gendall referred to Burrett's case, in which Justice Gerald Nation adopted a starting point of 26 years. However, Justice Gendall noted two of Burrett's victims were "severely mentally and physically disabled" and Walmsley's offending was "not quite as severe".
In another case where a pastor raped children aged six and seven over the course of 16 years, a 20-year sentence had been imposed, the court heard.
However, the judge noted Walmsley abused more children and on more occasions than the pastor.
He also continued his abuse after a police investigation in 2000 ended with no prosecution.
"Instead of curtailing your conduct it seemed to give you more confidence."
The judge said the effects of offending like Walmsley's "permeates society at many levels", making people less trusting and leading people and policy makers to hold "grave fears" about allowing children and young people to be in CYF care.
Walmsley's lawyer, Craig Ruane, acknowledged the extent of his client's crimes, but suggested he "could be given some credit for what has otherwise seemed to be a generally productive life".
He had contributed to charities, sport clubs and other organisations, Ruane said.
Any question of Walmsley getting parole after 10 years was "academic" because he remained in denial about his offending, he said.
Ruane suggested a starting point for sentencing of 20 to 25 years, but accepted "anything less than 20 would be inappropriate".
Crown prosecutor Andrew McRae suggested a starting point sentence of 24 to 26 years, with a 10-year minimum non-parole period.
The judge found Walmsley's sustained offending "undermines totally any claim to recognition of previous good character", but also concluded there were no aggravating features of the offending to be factored in after a starting point sentence of 22 years.
If Walmsley serves his entire sentence, he will be 79 when he leaves prison.