The graphics on the boats change with each new design as well. What you're really trying to figure out is which version of the design he's selling; for instance, there are three generations of the Fun, three generations of the Stars, and two generations of the Hero. Each generation has a different graphic for the name of the design. Post a picture of the boat's "name" and it'll be easy to tell which generation it is.
"A river is more than an amenity, it is a treasure."
-Oliver Wendell Holmes writing for the majority in New Jersey v. New York