Source: camp. but quite similar to what Bascom Lamar Lunsford recorded for Library of Congress in 1949.
Notes: Any occupation where people are at the mercy of immense dangers that they cannot control is likely to be full of superstitions. And sailors were a prime example. One strong belief was that it was very bad luck to set sail on a Friday. And you can understand that it would be considered extremely unlucky if the captain is seeing mermaids. This voyage is doomed from the start with a double whammy of ill omens.
The song started out as a very serious ballad in about 1765, but quickly got turned into a chorus song which seemed to grow lighter over the years. This is the way I learned it many years ago. The chorus: ?Oh the ocean waves may roll, And the stormy winds may blow. While we poor sailors go skipping up aloft and the landlubbers lie down below, below, below and the landlubbers lie down below?