The name Gwennan Gorn (or Gwennangorn) is given to a ship reportedly designed and built by a sea-voyager named Madog ab Owain Gwynedd in a document by Welsh copyist and collector Roger Morris written in the 1580s. According to this document: Ceridwen Lloyd-Morgan discusses 18th century tales stating that King Arthur was said to have had a ship named Gwennan which was wrecked on a dangerous sandbank off Bardsey in an area of the sea called Caswennan.