Sometimes criminals face supernatural retribution for their crimes. In the Finistère region of Brittany, it is the victim that suffers instead. Crimes committed on board develop a life of their own and linger long after the guilty party has left the ship. Acts of greed summon evil spirits that populate the ship, bringing bad luck to the crew. In such cases humid straw must be burned to fumigate the ship. The demons can become small enough to hide in a thimble, so the smoke must reach every part of the ship. This must be performed before heading out to sea to avoid potential disaster.
In Audierne, committing a maritime theft actually guarantees good luck. The creature left behind is a Bosch, the physical manifestation of onboard theft. They have no clear appearance, and probably vary depending on the nature of the crime they embody. These wretched creatures come into existence after a theft occurs on a ship, and have a lifespan of a few months to a few years, at the end of which they weaken and disappear. During this time they hide in the bow of the ship and make life on board absolutely miserable. As long as a bosch is present, the nets will be empty, the wind will not blow, and bad luck will hound the crew.
Simply waiting for a bosch to die is therefore impractical. If a ship finds itself afflicted with a bosch, there are two ways to get rid of it. One is to steal an object from a “happy” ship, one whose crew is satisfied and whose catches are always plentiful. The ship should be moored near it, and during the following night the captain sneaks on board the other ship to steal some small object, usually a pair of oarlocks. The bosch will then go to other ship and become their problem.
If one does not wish to inflict the misery of a bosch on an innocent ship, the demon can be exorcised instead. The captain must steal a quantity of hay and hide it in the boat. At night he should set fire to the hay near the mizzenmast and yell “Devil on board!” The sailors, startled, will grab anything within reach and lash out randomly, beating every corner of the ship. Surrounded and beaten, faced with choking smoke and scorching flames, the terrified bosch dives into the sea.
van Hageland, A. (1973) La Mer Magique. Marabout, Paris.