When her father refused to turn up, the truancy agency notified child protective services, infuriating the family.
"Who knows, maybe they'll be waiting for her with handcuffs at the finish line," Mr De Lange said.
A Dutch court originally blocked her voyage and only permitted her to set off after she bought a bigger, sturdier boat than the one she originally planned to use; fitted it with advanced navigation and radar equipment; enrolled in a special correspondence school; and took courses in first aid and coping with sleep deprivation.
Laura was born on her parents' yacht when it was docked in Whangarei, making her a New Zealand citizen.
Mr De Lange said Laura plans to return to school after her voyage, although she is considering relocating to New Zealand.
While Laura is aligning herself more to her birth country, her Australian manager Lyall Mercer complained in August she had "failed to find any support from New Zealand" and had then been unable to source a New Zealand flag to fly from Guppy.