Susan Blyth Neill-Fraser, 57, of West Hobart, was found guilty in 2010 of murdering her long-term partner, Bob Chappell, on board their yacht moored on the Derwent River.

His body was never found.

Neill-Fraser's appeal against her conviction was dismissed.

Her appeal against her 26 year prison sentence with a non-parole period of 18 years was allowed, with Chief Justice Ewan Crawford re-sentencing her to 23 years' imprisonment with a non-parole period of 13 years.

Neill-Fraser's daughters Sarah Bowles and Emma Fraser-Meeker said they were disgusted by the outcome of the appeal.

``We stand here today saying that we are not going to be happy until our mum is fully acquitted and if this means proving to the Tasmanian community that she had no involvement regardless of the fact that it's very difficult to do in a circumstantial evidence case that is what we aim to do,'' Mrs Bowles said.

``It is going to be extremely difficult. We're already under enormous financial strain, we have to seek leave to appeal to the High Court and have that granted and ... I don't think we could go there with anything less than best barristers we can find because that seems to be our only chance left.''