The best finish for the 25-year-old Wairoa-born athlete before that was fourth in 2014.
The former Napier Boys' High School pupil recalls sitting at his home, swotting for his exams as a 17-year-old when he noticed Lake to Lighthouse competitors trying to negotiate Wairoa River just before the finish line.
"The kayaks came and I could see them from across my house so I went to cheer them on. I knew the first and second-placed people and I knew they were the best and used to do Coast to Coast so it was quite motivating and it certainly helped me," he says, revealing he was no brain box but passed his NCEA papers.
As it turned out his home was instrumental in carving a niche for him in the Air Force.
The airport is within earshot of their 4ha lifestyle block property up the river.
His mother, Vicky, and father Peter Manson aren't athletes by any stretch of the definition of the word but she was conducive to stimulating a desire for everything whitewater kayaking.
"White water kayaking was a huge advantage over others in the Coast to Coast for me," says Manson, who took it seriously from 15 and developed it through the Hawke's Bay Kayaking Club while boarding at NBHS.
Vicky, who was a nurse in Marlborough, had built a fibreglass kayak in the early 1980s which her son put to good use at Wairoa River.
"There was a bit of equipment around the house and a fair bit of history so you get ideas and take interest in it yourself."
His father often took him to tramping or yachting to be in harmony with nature so when he embarked on multisport surprise turned to support.
No doubt the outdoor-loving parents travel to the event every year to be part of his support crew and are immensely proud of him.
Defending champion Sam Clark, of Whakatane, retained his crown in 11h 2m to run down three-time champion and race leader Braden Currie to finish eight minutes ahead.
"They are very experienced triathletes as well as multisporters who have been doing it for twice the amount of time I have been doing it for," says Manson, who took his first stride into a professional existence this summer when work went on the back burner.
"I had time for rest and recovery but when it got too sore I went back to work," says the aircraft technician who was based in Auckland and moved down to Christchurch for a polytech course.
Manson, an airforce graduate, invested an average of three hours a day but about six to eight on the "longer days".
The goal was to average around 15 hours a week but he often found himself doubling that, refining the transition between disciplines and terrain specific routines.
"I do all the disciplines and sometimes I do them all in a row. Sometimes there's no path because you're going from one rock to another for 33km."
Building strong ankles for agility is essential and so is keeping the kayak in the straight and narrow in rapids.
He first heard about multisport when he was 17 from a friend.
Manson had never got into a cycling saddle at that stage but the concept had appealed to him.
"I didn't start training until I was 20 because I didn't have work to buy a kayak and a bike, but when I left school to get into the airforce for a job I could afford to buy stuff."
Winning a race was his motivation in those days rather than trying to complete so the aggressive stance often took its toll.
"I thought at the time when I started I could train properly and be fast enough to win it in one year but, you know, how wrong I was."
Manson is aware that an athlete's body matures in the late 20s and early 30s so he has to be patient.
"I'm not quite there yet but I'm training the right way and you need to be a bit more professional about it."