Wellington, March 1 NZPA - Sports trainer Malcolm John Platt has lost his appeal against conviction for raping and sexually violating a 16-year-old girl.

But the 47-year-old Christchurch man has had his 10-year jail term reduced to eight years, and the Court of Appeal, in a decision issued today, has also set aside a minimum four-year non-parole period.

Platt, who maintained the sexual activity was consensual, was sentenced in Christchurch District Court last May by Judge Michael Crosbie, who said the that the girl, who had some mild intellectual impairment, had suffered "not inconsiderable sexual trauma".

"The impact for this young woman is that if she did not already have enough trouble in her life, she will now have considerable issues as a result of this," Judge Crosbie said.

Platt had been in custody since a jury found him guilty on three counts in March.

In its judgment, the Court of Appeal said it agreed with the submission by Platt's lawyer that he was a mature offender and the likelihood of reoffending was remote.

In any event where sentences of imprisonment were imposed for sexual crimes the Parole Board rarely considered parole until two thirds of the sentence had expired, so there was no need to impose a minimum period of imprisonment.