Grant Eric Brown, 31, of Hobart, was given a maximum two-year jail term last month after pleading guilty to recklessly causing grievous bodily harm to John Edward Lane.

As a result of the unprovoked attack, the 70-year-old victim suffered permanent injury when he was punched in the face and fell to the deck of a Manly ferry on November 16, 2009.

Brown was granted bail pending his appeal in the NSW District Court, where Judge Ronald Solomon yesterday suspended the jail term and placed him on a two year good behaviour bond.

"I have suspended the sentence - that means you are your own jailer for the next two years," he told Brown.

"If there is any trouble in Tasmania, or elsewhere, I will be informed."

He warned that if Brown breached the bond, he would have no hesitation in sending him to jail.

The judge said that Brown had become angry on the ferry while on the phone to his girlfriend, resulting in other passengers becoming uncomfortable with his aggressive behaviour.

A 64-year-old friend of the victim spoke to Brown and the two men decided to move away from him.

"(Brown) was seen to punch a fire extinguisher on the ferry, acting in a most aggressive and disgraceful manner," the judge said.

When Mr Lane told Brown "nobody should talk like that in front of ladies", he was punched.

Brown had not taken his medication for depression for four days, which the judge said had made him very agitated.

The victim's injuries included loss of hearing, numbness in his mouth, blurred vision, nightmares and ongoing psychological problems.

The judge noted Brown, who had been "well thought of in Tasmania", had taken steps to overcome his anger problems, including counselling.

He had been a mentor to young boxers and "a fine young man who gave his time to his family and to his community", the judge said.

Brown told the judge he was deeply remorseful and disgusted and embarrassed about his actions.

He spent 51 days in jail on remand, before being granted bail before the Local Court sentencing.