What do I say

[Water Camper]

What do I say to a friend who has just posted pictures on facebook of his underage kids driving a power boat ?
He is a new member of a local boating club.
He and his wife just recently took their boating safety course and are not previously regular boaters.
I feel I need to say something for their and everyone else's safety, but am at a loss as to how to approach this subject.

Thank You in advance for any advice.
Bill