"Once it died, Dad said 'oh no, you can do it this time'. He kept telling me 'keep going' and my brother was feeding me barley sugars."
Five hours later the winner came aboard.
"I couldn't really believe it. it was quite big."
The trio arrived back at the club to applause from other competitors acknowledging the mammoth catch from such a young junior.
"It was good because I knew it was my own," she said.
Club manager Rolly Bagshaw said it was "a heck of an effort" for a 12-year-old entered in the age 12 to 17 category.
"She got a big applause from everyone at the club because they all knew the huge effort that it would have required," Mr Bagshaw said. "It's an exceptional catch given her size."
Lucy's catch was "pending" as a New Zealand record for blue marlin caught in her age group and line weight class, he said.
The tournament coincided with a "really nice run of fish" thanks to warm and clear water and good currents, Mr Bagshaw said.