WILLIAMSON TURNS
The path that a ship follows during a Williamson Turn becomes even more predictable if the variables of the maneuver are eliminated. For example, instead of stating that the ship should be steadied up after she has reached a course that is 60 to 65 degrees from the ship's original course, it is preferable to state that the helm should be shifted at some predetermined point and left in that position while the ship checks up and then swings to the reciprocal of her original course. If the classic instructions are followed, the turn is less predictable because the time to check the swing and the amount of rudder used are dependent on the helmsman's or deck officer's experience and judgment.
The classic turn always uses a 60-degree change, this point and the amount of rudder needed to steady the ship were defined so all variables were eliminated from the maneuver. In this case the rudder was shifted hard over to check the swing when the ship's heading was 15 degrees from the reciprocal. Tests should be done by the master for his particular ship before the need to maneuver in an actual emergency arises. The Williamson Turn must be performed routinely during an ocean passage as part of the crew emergency training, and the point at which the helm is to be shifted should be determined by trial and error during those exercises. If a deeply loaded, large beam tanker that is directionally unstable were to follow the classic instructions, she would never return to her original track. If the rudder is shifted when that vessel is 60 degrees from the initial heading, she swings well past the desired point since it takes a great deal of time to check the swing of such a ship. The directionally unstable vessel then turns more rapidly toward the reciprocal heading since her turning rate is so much greater.
A Williamson Turn is defined as follows:
Put the rudder hard over toward the side on which the person has gone overboard and keep it there until the ship is 35 to 50 degrees from the initial heading. (The precise point for a particular vessel is to be determined by trial.) Shift the helm hard over in the opposite direction. Keep the rudder in this position while the ship swings all the way around toward the reciprocal of the ship's heading at the time the Williamson Turn began. When the ship's heading is 10 to 15 degrees from the reciprocal of her initial course, at a point determined by trial, shift the helm hard over again so the ship steadies up on the desired reciprocal heading.
Only three movements of the rudder are necessary, and that these changes in helm are at defined points that are not dependent on the watch officer's judgement.
The engine speed is not changed during the Williamson Turn. By maintaining revolutions, the rate of turn is predictable, the ship returns to the desired point in the minimum time, and speed is still sufficiently reduced. Everything depends on your ship and how it handles, regardless of the manoverboard maneuver used, the person or object in the water must be watched at all times; this is even more important than the correct execution of the Williamson Turn. If sight is lost of a person in the water it is difficult to locate the person again.
By throwing a life ring and other available objects into the water as close to the person or object as possible, with a light, dye marker, smoke flare, or other aid attached, the task of locating that person is greatly improved.
