The Williamson turn is an alternative manoeuvre used to bring a ship or boat under power back to a point it previously passed through, often for the purpose of recovering a casualty at sea. It was named for John Williamson, USNR, who used it in 1943 to recover a man who had fallen overboard.

The Williamson turn is a classic nautical maneuver used primarily for bringing a ship back to its original track to recover a person who has fallen overboard (Man Overboard). It is particularly effective when the exact time of the incident is unknown or in conditions of low visibility, such as at night or in heavy fog. To execute the turn, the rudder is first put "hard over" toward the side the person fell. Once the ship has deviated 60 degrees from its original course, the rudder is shifted "hard over" to the opposite side. The turn continues until the ship is approximately 20 degrees short of the reciprocal (opposite) course, at which point the rudder is centered so the ship steadies up on the exact opposite of its original heading. This maneuver creates a "loop" that places the vessel back on its original path, allowing the crew to retrace their steps and search for the casualty. While modern GPS "Man Overboard" buttons have made navigation easier, the Williamson turn remains a fundamental safety skill taught to all professional mariners and offshore sailors worldwide.