The producers of this particularly Popeye cartoon got lazy and decided to spend much of the time using footage of a past episode. "Cheaters," I guess, is what they call that kind of practice. Anyway, I think it's a cop-out and lazy way to present a "new" animated short.
It begins with Popeye bringing three nephews into the "Nautical Hall Of Fame." There, he shows them "Washington Crossing the Delaware" in which the kids then start rowing the boat across the room. Then, it's "Noah's Ark," where Popeye notes that Noah was "the world's first sailor." Then the shows the kids a big statue of "Sindbad, the Greatest Sailor In History.
The kids ask Popeye, "We thought YOU were the greatest sailor in the world." Popeye answers, "I am," and then relates the story of his adventures with Sinbad - in which we get footage of the earlier cartoon "Popeye Meets Sindbad The Sailor."
There is a cute ending when the story is over and the nephews are convinced Popeye is still number one.