Merit-Time Adventure

S1, E40: Scrooge goes after a mysterious "Sea Serpent" that has been sinking his ships and terrorizing the sea lanes off Duckburg harbor. He is aided by Launchpad, the Nephews, Doofus and Webby, who are vying for Junior Woodchuck sailing merit badges. They meet various characters, all of whom are suspect as the perpetrators, when the "Monster" turns out to be a mechanical device for stealing cargo!