Those three friends joined more than a thousand others at his funeral service at Port Macquarie on Saturday.

Whistles, screams and clapping filled Saint Columba school hall as the service opened with a Christian rock song to kick off what really was a celebration.

The talented bodyboarder, 19, was surfing a popular break north of Coffs Harbour on NSW's mid-north coast when he was mauled by a tiger shark as his friends watched in horror a week ago.

His father Kevin stood next to his son's rainbow coloured coffin and told the packed hall that his son "stretched his idea of love".

This was the second time Mr Young was forced to say goodbye to one of his sons. As he spoke about the loss of Zac he also paid tribute to his other deceased son, Issac Young James.

The tin roof of the hall vibrated with a thunder of loud clapping when Mr Young said his goal in life was to be more like his son.

Just two years ago the 19-year-old had turned his back on a wild, party lifestyle and was training with a Christian organisation, Youth for Christ.

Many religious songs were played, with the help of a drum kit with Zac's name scrawled across the front.

Zac's family and friends tapped their feet and some threw their hands up in the air as their bodies swayed from side to side as a live band belted out some of his favourite Christian tunes.

His close friend Dave Malvern spoke about Zac's love of God and caused the crowd to burst into laughter as he rapped some of his tribute.

"Zac just brought this freshness of life to us. It was just a like a party everywhere he went.

"He felt like a son, I loved him so much. I was so proud of who he was becoming.

"We love ya, we'll miss ya and goodbye."

Many of Zac's friends were dressed in bright shirts, board shorts with sunnies perched on their heads – a reminder of the laid-back and casual teen who made so many people feel at ease.

Family members gave out crosses to all who entered the hall, made out of drift wood and tied up with string.