Shipowner
A private individual or company running a private or commercial vessel. He fits out a yacht, meaning that he supplies all material, equipment and pays all relevant expenses to run the ship properly.
Captain
Master on board, responsible for all operations. In charge of navigation, accounting, legal and regulatory compliance, crew management, safety for passengers, crew environment and vessel.
First officer
Assists the captain in administrative and safety duties, but also in crew management (schedules, discipline). Must have a sufficient diploma to stand in for the captain in case of emergency.