The Vestris - S3.E25

In the spring of 1828, the bark Vestris, is 16 days out enroute from England to Boston. The weather is fair, but the captain's ailing wife suddenly has a vision telling her (in a message written on a blackboard) to have the ship change course. At first the captain refuses, but when the weather changes and his wife becomes sicker, he reluctantly agrees. As a result, they find and rescue three survivors of a shipwreck. One of the three is a doctor, and appears to be the ""spirit"" seen by the wife. He saves her life. As it turns out, the message on the blackboard is in his handwriting. Curiously, the doctor is as puzzled as everyone else by the wife's vision.