Square rig
Square rig is a generic type of sailing vessel in which the main spars are perpendicular to the keel of the ship. It was the main design in the age of sail.
It can refer also to individual sails carried on either a square-rigged or a mainly fore-and-aft rigged vessel, such as one with either a bermuda rigged or gaff rigged mainsail.
Square-rigged vessels range in size from small sloops to full rigged ships. However even for the largest vessels, the rig has been largely replaced by fore-and-aft gaff rigs and bermuda rigs, which give superior all-around performance with far smaller and less skilled crews. Similarly, hybrid vessels carrying some square-rigged sails have largely disappeared.
A square-rigged sail is not in fact square, but more nearly trapezoidal, being symmetrical but longer in the foot than the head. Like all sails it is three-dimensional, and its curve or belly means its foot is not a straight line at all. It is fixed to a spar along its head, and its clews are controlled by sheets, often run to blocks on the spar immediately below the sail.
Modern square-rigged ships are still used for training, tourism and ceremonial purposes.
Types of square rig
Principally square rigged types
- A barque has three or more masts, with the mizzen entirely fore-and-aft rigged, while the fore, main and any others are square rigged.
- A brig has two masts, both square rigged.
- A full rigged ship has three or more masts, including a foremast, mainmast and mizzen, and all masts are square rigged.
- A sloop has only one mast.
All the above rigs normally carry a number of jibs and a spanker, and may also carry fore-and-aft staysails between the masts.
Fore-and-aft rigs with some square rigged sails
- A barquentine has three or more masts, the fore square rigged, the main, mizzen and any others fore-and-aft rigged.
- A brigantine has two masts: A square rigged foremast and a fore-and-aft rigged mainmast.
- A square-topsail ketch carries one or more square-rigged topsails (commonly two, an upper and a lower topsail) on its mainmast, in addition to its mainsail, mizzen sail and jibs.
- A square-topsail cutter or sloop carries one or (less commonly) two square topsails on its only mast, in addition to its mainsail and jib or jibs.