Someone who owns a boat is commonly referred to as a "boat owner." If the boat is specifically a yacht, they might be called a "yacht owner." Additionally, in more casual terms, they could also be called a "boater" or "mariner."
Someone who owns a condominium unit is called an owner.
An Aquatic Nomad
Barmaid or Landlord Waiter or waitress if they work there
a proprietor or a shareholder depending on the circumstance
whoever owns the company that he sails for or if he owns the boat and is on a crew than the skipper of the boat
A person who owns 20 or more slaves would be historically referred to as a slaveholder or a plantation owner.
janet jackson
Roman Abramovich
A boatowner is a person who owns a boat.
Another name for a business owner is an entrepreneur. sole proprietership
Jim Pattison
Larry Silverstein