Siblings have a reputation for competitiveness and 15-year-olds Casper and Astrid de Wolf from Belgium are no different.
From a town called Waasmunster, in north Belgium, the twins are in Napier with the Belgium team for the Optiworlds and have been sailing together since they were 6.
Astrid recalls crying a lot during her first year of sailing. "I didn't like the wind or the water, I was headstrong so when I said 'no', it really meant 'no', and I didn't like being last in the races and always being behind my brother."
This natural dislike - both of sailing and losing - was eventually turned around by hard work.
"This year I just said, 'now I am going to be positive, I am better, and I'm going to sail better'."