Square rig is a generic type of
sail and rigging arrangement in which the primary driving sails are carried on horizontal
spars which are perpendicular, or
square, to the
keel of the vessel and to the masts. These spars are called
yards and their tips, beyond the last stay, are called the
yardarms. A ship at least partially so rigged is called a square rigger.
The term can also describe individual, four-cornered sails suspended from the horizontal yards, and carried on either a square rigged or a mainly fore-and-aft rigged vessel, such as one with a bermuda rigged or gaff rigged mainsail.
The term is also used for the uniform of a rating in the Royal Navy since 1857. It is slang and refers to anyone wearing the famous blue square collar on the shoulders and bell-bottomed trousers. The name perhaps reflects the fact that it was these men who managed the square rigged sails. The peaked cap uniform worn by Senior Ratings (Petty Officers, Chief Petty Officers and Warrant Officers) and Officers is known colloquially as 'fore and aft' rig.
A mast is considered square rigged if its lowest sail or course is square rigged, but normally if this is the case it will have a complete set of square rigged sails. If the course is fore-and-aft, square topsails can still be carried in front of the mast.
