Composite sailing.-When the great circle would carry a vessel to a higher latitude than desired, a modification of great-circle sailing, called composite sailing, may be used to good advantage. The composite track consists of a great circle from the point of departure and tangent to the limiting parallel, a course line along the parallel, and a great circle tangent to the limiting parallel and through the destination.
Solution of composite sailing problems is most easily made by means of a greatcircle chart. Lines from the point of departure and the destination are drawn tangent to the limiting parallel. The coordinates of various selected points along the composite track are then measured and transferred to a Mercator chart. Composite sailing problems can also be solved by computation.
