He and his staff member William Pei won the New Zealand Fencing Competitions doubles title at Southern Field Days near Gore in February this year.
The pair won the prize by being the best duo to install a fence about 30m long featuring three wires through Y posts and rabbit netting.
A job installing 1.6km of rabbit netting on Stoney Creek Station near Gore a few months before the competition gave them an edge over other competitors, Mr Sinclair said.
They had also recently installed about 800m of rabbit netting in Roxburgh.
"We were pretty lucky because as we work together daily, it was easy enough to make a system."
To win, competitors needed to be "fast, efficient and tidy", characteristics they targeted at work.
They were one of seven teams competing at Waimumu.
After the first team finished, the remaining teams were given a point penalty for every minute until they finished.
Once every team finished, judges gave teams point penalties for defects in the fences.
The team with fewest points won the competition.
Prizes for winning at Waimumu were automatic entry to the Fieldays Fencing Competition silver spades doubles championships finals to represent the South Island in Waikato last month.
Competition organisers got them to arrive early to learn how to operate some of the fencing machinery in the North Island, such as a modified drill featuring a 90cc chainsaw.
"They made sure you felt at home. Everyone up there was very inviting and there were no secrets and they were more than happy to help us out with tools and advice. They were a real bunch of good buggers," Mr Sinclair said.
The pair placed seventh in a field of eight teams in the silver spades competition.
Mr Sinclair competed in a field of 26 individual fencers to qualify for the Bill Schuler competition.
"I thought I’m there so I might as well give the singles a crack."
He placed second and won the prize for the best first-year competitor.
The experience at Fieldays had him hooked on the national fencing competition and left him wanting more.
"I loved it."
Mr Pei had entered two fencing competitions but Mr Sinclair had been competing for a decade, alternating between Southern Field Days and the South Island Agricultural Field Days in Kirwee, often competing as an individual.
"I enjoy the singles and working by myself because then I can hold myself responsible for anything wrong with the fence," Mr Sinclair said.
The appeal of the sport was "getting a sweat up" and testing himself against like-minded competitors.
His business, Craig Sinclair Fencing, was going OK despite a reliance of work on sheep and beef farms.
Fewer of those jobs were available at the moment as farmers cut costs by delaying getting a fencing contractor in or doing the work themselves.
Fencing around bodies of water for local councils in urban areas was keeping his business ticking over, he said.
Born and raised on a sheep and beef farm near Owaka, he left school to work for contractor South Otago Fencing.
"My dad Ian was doing a lot of development on the farm and that’s where I found my passion for fencing."
A desire to own machinery and be his own boss prompted him to launch his fencing business in 2009.
He was working on his own for three years and word-of-mouth spread about his work and he now employs two staff.
To make money, Mr Sinclair and his wife Georgia developed a 220ha sheep and beef farm in Tuapeka West, clearing gorse and fencing the property, which they sold last year.
A goal of the couple was to buy some land to develop and get back into farming.
Now they and their daughter Savannah, 2, were living in a cottage on his parents’ farm near Owaka.
"That’s where we are filling in our time until we find a chuck of dirt with a house on it."
