Masts, Sails, and Spars on Square Rig Sailing Ships
This square-rigger is equipped with traditional square rig sails, gaff rig sails, and fore-and-aft sails.
The tallest mast on any sailing vessel is called the main mast.
A mast located forward of the main mast, if there is one, is the fore mast.
Masts located aft of the main mast include the mizzen mast, jigger mast, spanker mast, driver mast, and pusher mast. Masts would sometimes be referred to by number rather than name, as in mast number 4.
A mast that is considered fully square rigged will have 3 spars and at least 3 sails. The spars are the lower mast, topmast, and topgallant mast. The topgallant mast holds the topgallant sail; the topmast supports the topsail, and the lower mast supports the course. Sometimes, the topsail is so large that it is made of 2 separate sails for easier handling: the lower topsail and the upper topsail. On large ships, the topgallant sail sometimes comprises 2 separate sails for the same reason.
Many large square rig sailing ships include a royal, above the topgallant mast. Occasionally, sailing ships would include a skysail above the royal, and more rarely, a moonsail or moonraker above the main skysail.
Square sails are typically named according to the mast they are attached to. The course is the sail on a lower mast — the course on the lower mast of the fore mast (the fore lower mast) will be the fore course, and the course on the main mast is the main course. There are exceptions: The course on the mizzen mast, for example, is called a crossjack, or cro'jack.
Traditional square rig sailing ships would frequently include additional sails to achieve faster speeds and greater control. Clipper ships often carried additional square sails on either side of the main square sails, and staysails were frequently rigged to the stays. Staysails increase the vessel's stability, while additional square sails increase her speed.
A large square rig sailing ship might carry as many as 34 sails. Because of the force imposed on square rig sails, the strength limits of the materials in use, and the logistics and limits of the manpower needed to handle the sails, multiple smaller sails were frequently used rather than a smaller number of larger sails.