Sea anchor

A sea anchor (also known as a drift anchor, drift sock, para-anchor or boat brake) is a device used to stabilize a boat in heavy weather. Rather than tethering the boat to the seabed, the sea anchor increases the drag through the water and thus acts as a brake. When attached to the stern of a vessel, a sea anchor can prevent the vessel from turning broadside to the waves and being overwhelmed by them.

Often similar in design to the sea anchor is the usually smaller drogue, which is attached to the stern and intended to slow the boat for better control.

Design

Anything that can act as a source of drag in the water can act as a sea anchor; a common improvised sea anchor is a long line (a docking warp or anchor rode) paid out into the water; while this does not provide much drag, it can act as a drogue and aid in running downwind. In The Sea-Wolf, author and sailor Jack London described using various torn 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.