Clambake (1967)

Scott Heyward, the son of a millionaire, is tired of women fawning over him because of his wealth. When he meets Tom, who is on his way to his new job as a water-skiing instructor at a hotel, they envy each other's lives--and decide to switch places. Scott pretends to be Tom and Tom lives it up pretending to be Scott. Scott meets Dianne, who is trying to land a rich guy, and when playboy James Jamison catches her eye, she asks Scott to help her snag him. Scott agrees, but finds himself attracted to her. Scott also decides to build a boat for a speedboat race that's to take place in the hotel but he's using a new experimental chemical which doesn't hold in water, which his father forbade him to use.