Barrelman is in reference to a person who would be stationed in the barrel of the foremast or crow's nest of an oceangoing vessel as a navigational aid. In early ships the crow's nest was simply a barrel or a basket lashed to the tallest mast. Later it became a specially designed platform with protective railing.

According to a popular naval legend, the term derives from the practice of Viking sailors, who carried crows or ravens in a cage secured to the top of the mast. In cases of poor visibility, a crow was released, and the navigator plotted a course corresponding to the bird's flight path because the crow invariably headed towards the nearest land.^[1] Some naval scholars have found no evidence of the masthead crow cage and suggest the name was coined simply because the lookout platform resembled a crow's nest in a tree.^[2] As ships grew in size and complexity, that station came to be mounted on the highest mast of the oceangoing vessel, and it came to be known as the crow's nest.^[3] The simplest construction to providing a lookout and setting course direction for the ship was to lash a barrel to the mast. A member of the crew experienced in the matters of navigation was charged with manning this perch and came to be colloquially known as a barrelman.

In Newfoundland the term barrelman was synonymous with the word scunner.^[4]

• Glossary of nautical terms