A sail-plan is a set of drawings, usually prepared by a naval architect
Naval architecture
Naval architecture is an engineering discipline dealing with the design, construction, maintenance and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation and calculations during all stages of the life of a...

. It shows the various combinations of sail
A sail is any type of surface intended to move a vessel, vehicle or rotor by being placed in a wind—in essence a propulsion wing. Sails are used in sailing.-History of sails:...

 proposed for a sailing ship
Sailing ship
The term sailing ship is now used to refer to any large wind-powered vessel. In technical terms, a ship was a sailing vessel with a specific rig of at least three masts, square rigged on all of them, making the sailing adjective redundant. In popular usage "ship" became associated with all large...


The combinations shown in a sail-plan almost always include three configurations:
  • A light air sail plan. Over most of the Earth, most of the time, the wind force is Force 1
    Beaufort scale
    The Beaufort Scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort Wind Force Scale.-History:...

     or less. Thus a sail plan should include a set of huge, lightweight sails that will keep the ship underway in light breezes.
  • A working sail plan.