"It's been a learning curve. I came here to learn what it takes to be a professional coach. I thought it was easy. I made a few mistakes, learned from them and it's paid off."
Otumoetai's 19-strong team at February's junior nationals - the fifth biggest club presence - brought home five individual medals, achieving five Bay of Plenty records and 21 top 10 placings in the process.
"Getting that number of swimmers in was amazing, it was half the Bay of Plenty team. We rivalled the big teams from Auckland and Wellington. In 2011 we had 16 qualify and thought that would be hard to top, as it was the biggest number in the Bay," Swanepoel says.
Top club performer at the junior nationals, George Williams claimed silver in the 12-year-old boys' 200m freestyle, 200m individual medley (IM) and 100m backstroke, plus bronze in the 200m backstroke.
Describing his coach's attributes, the young all-rounder says: "Stefan trains us hard but keeps changing the session [format] which keeps it interesting ... he's encouraging and helpful."
The other Otumoetai swimmer on the podium at the Wellington meet was Thomas Chaney, who collected bronze in 11-year boys' 50m backstroke and also finished fourth in 50m butterfly.
"Thomas came out of nowhere," Swanepoel says. "Swimming at his first junior nationals, he made the finals when nobody expected it and got bronze. Everyone in our section in the stand was shouting wildly."
Praising the community spirit behind his club, 30-year-old Swanepoel recalls squad members' resilience in testing times last winter as a collective show of character.
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Tom Hacker of Otumoetai Swimming Club. Photo: Joel Ford.
Firstly the pool area's fabric roof ripped open, adding a chilly edge to early morning training. Then the hot water bore failed and pool temperatures dropped below 24C for about a month.
"The kids managed to get through it. If they enjoy the atmosphere they will come back," Swanepoel says. "I had a lot of pride in them for working through that."
While constant fine-tuning of his training methods is a given, Swanepoel's philosophy is the same as the day he arrived at the club.
"Technique is the key. These guys need to swim perfectly every time they're in the water. The focus is on the way they enter the water and move in the water, rather than on lots of distance work."
Anchoring the club is a clear pathway of squads from the Learn To Swim programme through to national competitors. Striking a balance between swimmers' hard effort and enjoyment, plus individual versus squad needs, can be a delicate thing.
"We had a strong sprinter presence in the national squad [13 years and over]. I had the squad doing a high-tempo kick for short bursts," Swanepoel explains.
"Jess Miller is a top 800m swimmer and that just didn't work for her. She was doing some phenomenal 50s but didn't have the endurance for the 800m free, so we went back to developing her long stroke again."
Aged 16, Miller is a freestyle powerhouse. At the New Zealand age-group titles at Wellington in March she bagged gold in the 800m, plus silver and bronze in the 400m and 200m distances respectively.
Also in the national surf lifesaving development squad - where she's joined by Otumoetai swimming clubmates Katie Wilson and Sam Shergold - Miller's long-term focus is on the beach as much as the pool.
"I really want to make the New Zealand surf lifesaving team and compete around the world. You work really hard so you want it to pay off."
Club member Andrew Newton is another successful surf crossover, successfully defending his board race title at the national surf lifesaving championships at Gisborne in March with the Mount Maunganui team.
To some swim coaches, surf lifesaving competition could seem a dangerous rival. But not Swanepoel.
"When I came to Tauranga I knew nothing about it, but it turned out that Spindles [Mount Maunganui coach John Bryant] and I work really well together. I get excited about going along and supporting our juniors at surf events. In the end, it's all about kids enjoying themselves in a healthy sport."
Given recent membership growth at Otumoetai, he has little to worry about.
"Numbers have exploded in the last couple of years.
But there's also a bit of allegiance to coaches.
"We lost a lot of swimmers when the previous coach [Hugh Doktor] left.
"Some mornings there'd be only three in the water. On Monday, Wednesday and Friday mornings now we have four lanes booked and 30-odd swimmers."
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Otumoetai swimming club member Jess Miller, competing at the 2012 Lion Foundation Surf League in Mount Maunganui. Photo: Jamie Troughton/Dscribe Journalism
The club is set to say goodbye to one of its success stories, paralympic competitor Tayla Clement, whose family is moving to Auckland.
At this year's national paralympic championships the 14-year-old took gold in 50m and 100m free plus silver in the 200m IM.
A member of the New Zealand Paralympic squad, she has her sights on the 2014 Paralympics at Rio. During his early days at Otumoetai, Swanepoel described himself as "addicted to coaching". Is the attraction still that strong?
"Oh definitely. It's a great feeling seeing kids progress.
"For example there's Isabella Akroyd, who we've seen go from basic stroke development to setting Bay of Plenty records.
"I think I get as nervous and excited as the kids at meets, and seeing these guys excel and get up on the podium is a terrific experience."