Sail-plan
![Sailing frigate and its rigging](/Images/godic/202502/08/Tackling0501.png")
![This photo of the Star of India provides not only good view of most of her sails, but also most of her standing and running rigging. The Star of India is berthed in San Diego, California, and is open to the public.](/Images/godic/202502/08/Starofindia0501.jpg")
![The names of all of the possible square rigged sails on one mast of a sailing vessel from the 19th century](/Images/godic/202502/08/Square_rigged_sail_plan.svg0501.png")
![](/Images/godic/202502/08/Sail_plan_proa.svg0502.png")
A sail-plan is a set of drawings, usually prepared by a naval architect. It shows the various combinations of sail proposed for a sailing ship.
The combinations shown in a sail-plan almost always include three configurations:
In all sail plans, the architect attempts to balance the force of the sails against the drag of the underwater keel in such a way that the vessel naturally points into the wind. In this way, if control is lost, the vessel will avoid broaching (turning edge-to-the wind), and being beaten by breaking waves. Broaching always causes uncomfortable motion, and in a storm, the breaking waves can destroy a lightly built boat. The architect also tries to balance the wind force on each sail plan against a range of loads and ballast. The calculation assures that the sail will not knock the vessel sideways with its mast in the water, capsizing and perhaps sinking it.