After finding a way to teach the ship's crew members to understand navigation, Nat, a self-taught mathematician and astronomer in eighteenth-century Salem, Massachusetts, writes down his explanations and compiles them into 'The American Practical Navigator,' also known as the 'Sailors' Bible.'A fictionalized look at Nathaniel Bowditch and how his knowledge of mathematics, astronomy, ships, and the sea led him to become a brilliant navigator.