Ethan Ewing emulates late mum by winning at emotional Bells Beach
Ewing's mother Helen, a champion surfer in the 1970s and 80s, won the longest running event in competitive surfing in 1983.
Forty years on, Queenslander Ewing dominated an all-Australian final against Newcastle surfer Ryan Callinan (30) in choppy conditions to savour an emotional triumph.
"Far out. It's crazy. This has been a crazy week," said Ewing, whose mother died of cancer when he was six.
"It's such a special thing, I’ve been thinking about her since I have been on the tour and it’s been a huge goal of mine. I want to do her proud."
His name will be etched on the World Surf League (WSL) event's trophy next to his mum's.
Both the finalists pulled off upsets on the way to the decider, with Ewing knocking out Brazilian three-times WSL champion Gabriel Medina (29) in the last 16 and Callinan taking down Hawaiian John John Florence (30) in the semi-finals.
The host nation was also guaranteed a winner in the women's event as reigning champion Tyler Wright (29) claimed the final against compatriot Molly Picklum (20), the pair having emerged from all-Australian semi-finals.
Twice world champion Wright's Olympian brother Owen (33), who announced his retirement last month, bowed out of pro surfing at the event with a first round defeat to Ewing.
"I didn't really think much of this week," said 29-year-old Tyler after coolly defending her title.
"It wasn't like last year when there was so much emotion in it as it took me 12 years to try and get the first one.
"To really execute this week the way I have, I'm really proud."
