"I thought I had lost it ... the line went slack, and I thought that was that."
Mr Marsh cast his line in early, at 7am, and by mid-morning was convinced history was about to repeat itself.
"I've entered every year for the last four or five years and never caught a fish. I didn't even win a spot prize," Mr Marsh lamented.
But just as hope began to fade, his fishing rod snapped forwards, the reel whirred into action, and line peeled off at speed - it was a big snapper.
"What a thrill. It was a real big fish to catch off the beach.
"It put up a good fight to begin with, then the line went slack. I thought I had lost it, but it was riding the waves in to shore ... I must have tired it out."
The snapper weighed in at 4.7 kilograms - more than a kilo bigger than the next best snapper caught on the day, and the biggest fish Mr Marsh had ever caught.
He won a new quad bike courtesy of Keown Honda, one of three major sponsors alongside David Jones Motors and Wilson's Hunting and Fishing. More than $40,000 in prizes was awarded.
The fishing adjunct-organised Monster competition lured 600 fishers on both days of the two-day event, with about 80 fish caught. Saturday was a teaser event with a $1000 prize for the biggest kahawai caught.
Many of those fishing camped overnight.
Organiser Ken Mander said numbers were down slightly on last year. He put that down to the competition taking place a few weeks later than normal due to tides and somewhere to set up headquarters.
"We're really grateful to the speedway for making its place available. Our usual HQ was booked out," Mr Mander explained.
He said fish were caught all the way up the beach, the sun shone and entrants were well behaved.
And the secret to Gary's big catch?
He saw a seal on the beach when he and friends arrived to set up camp on Friday - he thinks now it was a good omen.