Competitors then have a 15km bike ride to the banks of the Waimakariri River to begin the 137km kayak race down into Canterbury, before getting back on the bike for the final 120km leg into the outskirts of Christchurch city, before reaching the finishline on the Pier at New Brighton Beach.
Cox said the conditions were quite good for the race after a few days rain, although there was a slight head wind to overcome on the river and final bike ride to take away some of the speed.
Fellow Whanganui competitors Gareth Wright and Josh Barnett entered the Open (18-39) longest day race.
Wright would finish 31st (13h 56m) and Barnett would come in 48th (14h 36m).
This year's race was notable for the presence of retired All Blacks captain Richie McCaw and new wife Gemma Flynn, who entered the two day race.
Organisers have been trying to rebuild the prestige of the race and its falling entry numbers for a number of years, and Cox said it definitely appeared the field was larger than 2016.
Loving to race through the "beautiful scenery", he will check with the family if it is ok to do the race next year, committing to training and financially for another 12 months.
The men's and women's longest day races were both won by defending champions Sam Clark and Elina Ussher.
