"It's a big challenge to get ready and prepped up to show that you can really do it," he said.
His father Khan, who comes from a line of influential New Zealand surfers, including Matt and Paul Bennett, said Kehu caught his first wave as a 6-year-old and has not looked back.
"He really, really loves it. I think that's why he does so well, it's all he thinks about.
"Most of the other kids who are in this squad are in the same boat - they don't just do it because of the competitions and the accolades - they do it because they wouldn't be doing anything else anyway.
"He's just one of those kids who does everything he can to get to where he is going."
Kehu's younger sister Iritana is the national under-12 girls champion, meaning the Butler name is likely to be prominent in surfing circles for some time.
Mac, whose family moved from Tauranga to Mount Maunganui last year, has been putting in plenty of hours in the lead-up to the competition.
"We lived over the bridge but moved over last year. It's definitely helped my surfing ... Matakana Island tends to have fairly similar waves to Nicaragua by the sound of it, so I try to get over there as much as I can."
The Year 13 student at Tauranga Boys' College is weighing up whether to commit to tertiary study next year or to have a crack at the Australian circuit - a familiar decision facing many of our best young surfers with a declining number of events to compete in at home.
New Zealand has performed well at the annual event since 1989, with the highlight being Jay Quinn capturing the under-18 crown in 2001.
The Kiwi team placed 10th at the event in Panama last year and will attempt to wrest the SANZ Trophy - a unique prize made of solid pounamu and a paua inlay with a surfboard made out of South African hardwood - from holders South Africa in a tune-up for the competition proper.