"because what are the Dutch going to do, chase her down and shoot her ? "
No, but if someone her age has access to a bank account and can withdraw $5,000 (or euros or whatever) from it...in many places a prosecutor would go after the parents on contempt or conspiracy or other related criminal charges, and getting that news THAT could really put a crimp in her plans.
Slipping out the back door might be effective--but only if it was very carefully planned to prevent collateral damage. And then when she tries to clear into her first stop, well, someone might match up her name on a list and send her home under arrest anyway, leaving her new boat hanging on an impound dock someplace as well.
Not knowing the details...we can only guess that her memoirs will fetch a better price as the story gets more complicated.
That's my thinking too. If it is her making these moves, fine, more power to her, let a girl do whatever a girl can do. But if it is her father making these moves, suggesting she do this or that, making sure she has money, etc, and he is the resourceful one then he is the one who should be sailing around the world, not her. If it is her father that is providing the direction then I hope he really sits back and reflects on all of this before she leaves, is it really her wish to leave and sail around the world, or his ? If she really is self-directed enough to go whether he wants her to or not, fine, let her go, but if he is the one making the subtle suggestions, framing the dream in her mind, working behind the scenes to make it all work out for her, etc, then that's just wrong, that's putting a kid's life in danger, putting fancy dreams in her head and then not being there to make it all work out like he (presumably) always has. There are kids who are self-directed enough to do things like this, the kid that jumped in an airplane and flew it around then landed it comes to mind, now that was a resourceful kid.