Anything that can act as a source of sufficient stable drag in the water can act as a sea anchor; a common improvised drag device is a long line (a docking warp or anchor rope) payed out into the water; while this does not provide much drag, it can act as a drogue and aid in running downwind.Adding items to increase drag can convert this to a sea anchor. In "The Sea-Wolf", author and sailor Jack London described using various broken spars and sails, tied to a line, as an improvised sea anchor. A sail, weighed down with an anchor chain or other heavy object, will also work as an improvised sea anchor.