Commercial fishing is still the second most dangerous job in the US, and sailor superstitions grew as ways to feel in control of a sea that could kill at any moment. Older scholars dismissed them as childish folklore, but many hide practical sense. Red sky at night, sailor’s delight works in the mid latitudes because weather moves west to east. Whistling was said to raise a gale, but officers also feared it as a mutineer’s signal; only the cook could whistle, proving he was not eating the crew’s food. Bananas give off ethylene gas that rots other stores. Killing an albatross brought doom, and in Norwegian tradition cormorants were the spirits of the drowned.

In the 19th century sailors bought ropes from Finnish wind merchants with three knots: the first for a breeze, the second for a strong wind, the third for a gale. Clergymen, redheads, and women were shunned as Jonahs, though Pliny the Elder claimed a naked woman could calm a storm. Friday was the unlucky day for sailing, and cruise lines still skip decks 13 and 17. Cats earned their place as ratcatchers, and a University of Leuven DNA study traced cats spread along shipping lanes by eighth century Viking traders.

• Polydactyl cats were prized for balance, and throwing a ship’s cat overboard meant nine years of bad luck.
• A pig and a hen tattooed on the feet promised survival, since those animals floated away in their crates when ships sank.
• A baby’s caul was sold to sailors as protection against drowning.
• Franklin D. Roosevelt wrote to Eleanor about his line crossing initiation aboard the USS Indianapolis.
• One theory holds that Davy Jones is a corruption of Devil Jonah, with Fiddler’s Green as the sailors’ paradise.