How does James Gatz meet Dan Cody?

Gatz met Cody while he was walking along the shore of Lake Superior.

He had changed it at the age of seventeen and at the specific moment that witnessed the beginning of his career — when he saw Dan Cody’s yacht drop anchor over the most insidious flat on Lake Superior. It was James Gatz who had been loafing along the beach that afternoon in a torn green jersey and a pair of canvas pants, but it was already Jay Gatsby who borrowed a rowboat, pulled out to the Tuolomee, and informed Cody that a wind might catch him and break him up in half an hour.