Tanya Iremonger's adrenaline levels will probably kick back in when she is bestowed with her 2NZ title at the NZ Jetsprint Association's end-of-season prizegiving in New Plymouth in a fortnight.

The jetboat navigator from Waipukurau claimed a career highlight when she and her NZ River Jet driver Nick Berryman, from Rotorua, set a new record time as they won the sixth and final round of the series at Waitara in April to finish second overall in the elite Super Boat class.

"I'm not going to sugar-coat it - when we came back around the course [at Waitara] and I saw the timing screen I screamed, punched Nick in the arm and then I cried. Excitement can do funny things," said the 37-year-old mother of two about the win at Taranaki.

A veteran of the "physically and mentally demanding" sport despite her relatively young age, Iremonger is certainly no stranger to success in jetboat racing, having claimed 2NZ titles during the six years she raced with Auckland driver Baden Gray in the Group A class.


She was crowned the CHB senior sportswoman of the year in 2016 for those achievements but described claiming second place in her third season of racing with Berryman in the super boats as the highlight of her racing career.

"This is by far my personal best in my whole racing career since moving to the unlimited Super Boat class, and it's Nick's first title," said Iremonger.

"This season was particularly hair-raising. Every team was on the money, there were only hundredths to thousandths of a second between boats on the leader board during qualifying and eliminations. Not every round was a podium finish for us, but consistency was the key."

Iremonger credited the successful season not just to driver and navigator, but also to the third member of NZ River Jet's small team: Tim Coleman, from Coleman Marine & Performance in Marton, who built and maintains the engine for the stinger hull boat, which also runs a 8.75-inch Scott jet unit.

"The engine is an all-aluminium 410-cubic inch, small-block Chevy engine boosted by a Whipple Supercharger, [which produces] at least 1200 horsepower and runs on methanol.

"We are the only sprint boat in the world running a Whipple Supercharger. We are also pretty much the only competitive super boat out there with no data logger, so we have to tune old school, which is the exciting part," Iremonger said.

During the final round, the River Jet team enlisted mechanic Bronson Dunne to keep the motor "on song" and improve the boat's performance during the day.

"We had Bronson on board specially for the last round to take care of fuel. And would you believe we actually took the boost out during lunch break to calm the boat, which was an extremely brave move that paid off."

The pay-off is that she and Berryman will be able to proudly display their 2NZ title for the next 12 months after the season's prizegiving ceremony on June 30.

And after finishing only four points behind champion Peter Caughey, Iremonger was quietly looking to go one better next season.

"Is 1NZ an achievable goal? Anything is possible and we will certainly be back next season."