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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 The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
of the vessel and to the masts. These spars are called '' yards'' and their tips, outside the lifts, are called the '' yardarms.'' A ship mainly rigged so is called a square-rigger. The square rig is aerodynamically the most efficient
running Running is a method of terrestrial locomotion allowing humans and other animals to move rapidly on foot. Running is a type of gait characterized by an aerial phase in which all feet are above the ground (though there are exceptions). This i ...
rig (i.e., sailing downwind), and stayed popular on ocean-going sailing ships until the end of the Age of Sail. The last commercial sailing ships, windjammers, were usually square-rigged four-masted barques.


History

The oldest archaeological evidence of use of a square-rig on a vessel is an image on a clay disk from Mesopotamia from 5000 BC. Single sail square rigs were used by the ancient Egyptians, the Phoenicians, the Greeks, the Romans, and the Celts. Later the Scandinavians, the Germanic peoples, and the Slavs adopted the single square-rigged sail, with it becoming one of the defining characteristics of the classic “Viking” ships.The Viking ship's single square-rigged sail. http://Longshipco.org/sail.html Retrieved 2018-8-20 In their heyday, square-rigged vessels ranged in size from small boats to full-rigged ships. But this rig fell from favour to fore-and-aft gaff rigs and bermuda rigs after the development of steam power and new materials. Ocean-going sailing ships stayed mostly square-rigged.Square rigs allowed the fitting of many small sails to create a large total sail area to drive large ships. Fore-and-aft could be sailed with fewer crew and were efficient working to windward or reaching, but creating a large total sail area required large sails, which could cause the sails and cordage to break more easily under the wind. 18th-century warships would often achieve top speeds of , although average speeds over long distances were as little as half that. Some clipper ships that had square rigs and for whom speed was critical could be much faster; for example '' Cutty Sark'' could make . The late windjammers were as fast as the clippers, being much bigger. Not only could a smaller sail be managed by a smaller crew but also these smaller sails constrained the impact of weapons on them. A hole from a cannonball affected only one sail's area, whilst a hole in a large sail would eventually tear the whole larger area and reduce more of the vessel's motive power. With the development of more advanced fittings, equipment and cordage, particularly geared winches, high loads on an individual line (or rope) became less of an issue, and the focus moved to minimising the number of lines and so the size of the crew needed to handle them. This reduced running costs and also enlarged the space available in the ship for profitable cargoes. New materials also changed sail designs, particularly on hybrid vessels carrying some square-rigged sails. The low aspect ratio of square-rigged sails (usually to ) produces much drag for the lift (motive power) produced, so they have poor performance to windward compared to modern yachts, and they cannot sail as close to the wind. The Bermuda rig is the (nearly) undisputed champion of windward performance in soft sails, due to its very low drag and high lift-to-drag ratio. One advantage of square rigs is that they are more efficient when
running Running is a method of terrestrial locomotion allowing humans and other animals to move rapidly on foot. Running is a type of gait characterized by an aerial phase in which all feet are above the ground (though there are exceptions). This i ...
, where the high lift to drag is irrelevant and the total drag is the most important issue. Square-rigged sails are also less prone to
broaching The BROACH warhead is a multi-stage warhead developed by Team BROACH; BAE Systems Global Combat Systems Munitions, Thales Missile Electronics and QinetiQ. BROACH stands for ''Bomb Royal Ordnance Augmented CHarge''. Development of BROACH began ...
when running than Bermuda rigs. Ocean-going vessels take advantage of prevailing winds such as the trade winds and the westerlies and are thus mostly running. On multi-sail, multi-mast vessels, a square-rigged sail is not in fact square or rectangular, 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 that its foot (lower edge) is not a straight line at all. It is fixed to a spar (the yard) along its head, and its clews (bottom corners) are controlled by sheets that are often run to blocks on the spar immediately below the sail.


Terminology

Square-rigged masts may also have triangular staysails that are deployed fore-and-aft between masts. The term "square-rigged" 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 rig A fore-and-aft rig is a sailing vessel rigged mainly with sails set along the line of the keel, rather than perpendicular to it as on a square rigged vessel. Description Fore-and-aft rigged sails include staysails, Bermuda rigged sails, ga ...
ged vessel, such as one with a bermuda rigged or gaff rigged mainsail. " Square-rigged" is also used for the uniform of a
rating A rating is an evaluation or assessment of something, in terms of quality, quantity, or some combination of both. Rating or ratings may also refer to: Business and economics * Credit rating, estimating the credit worthiness of an individual, ...
in the
Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against Fr ...
since 1857. It is slang and refers to anyone wearing the conventional 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 fore-and-aft rig is a sailing vessel rigged mainly with sails set along the line of the keel, rather than perpendicular to it as on a square rigged vessel. Description Fore-and-aft rigged sails include staysails, Bermuda rigged sails, ga ...
'. A
mast Mast, MAST or MASt may refer to: Engineering * Mast (sailing), a vertical spar on a sailing ship * Flagmast, a pole for flying a flag * Guyed mast, a structure supported by guy-wires * Mooring mast, a structure for docking an airship * Radio mas ...
is considered square-rigged if its lowest sail or
course Course may refer to: Directions or navigation * Course (navigation), the path of travel * Course (orienteering), a series of control points visited by orienteers during a competition, marked with red/white flags in the terrain, and corresponding ...
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.


Characteristics

On a square-rigged mast, the sails have names which indicated their vertical position on the mast, and the masts are built in pieces named accordingly. The lowest square sail was the
course Course may refer to: Directions or navigation * Course (navigation), the path of travel * Course (orienteering), a series of control points visited by orienteers during a competition, marked with red/white flags in the terrain, and corresponding ...
and it was slung from the yard which was affixed to the mast. The next sail up the mast was called the topsail, slung from the topsail yard which was affixed to the topmast, the next the topgallant sail on the topgallant yard and topgallant mast. Although the lower three masts and sails were generally in position to be used as needed, only the lowest masts were always rigged; the upper yards, masts, and sails could be lowered or struck down entirely (removed) to reduce the potential leverage on the ship in increasing winds. Many vessels could ship a fourth sail, yard, and mast, called the
royal Royal may refer to: People * Royal (name), a list of people with either the surname or given name * A member of a royal family Places United States * Royal, Arkansas, an unincorporated community * Royal, Illinois, a village * Royal, Iowa, a ...
, above the other three, some even more on trades with light winds. Sometimes a vessel might put out studding sails which would be fixed outboard of these sails along the yards. Beginning in the mid-nineteenth century, the topsails and topgallants were each split into upper and lower sails; this allowed smaller crews to tend the sails and provided captains with a greater set of options in choosing which sails to set. Sails are referred to by their mast and then name, e.g., "the fore mast topgallant sail", often shortened to "fore t'gallant", or historically "fore t'gar'ns'l". Where no mast is specified, the main mast is implied.


Designation


Types of square rig ship

''See also Sail plans for illustrations''


Principally square-rigged types

* A cog has one mast, usually mid-ship, and one square-rigged sail. * A barque has three or more masts, with the aftermost entirely
fore-and-aft A fore-and-aft rig is a sailing vessel rigged mainly with sails set along the line of the keel, rather than perpendicular to it as on a square rigged vessel. Description Fore-and-aft rigged sails include staysails, Bermuda rigged sails, gaf ...
rigged, while the fore, main and any others are square-rigged. * A brig has two masts, both square-rigged. In addition to jibs and staysails (stays'ls) before the foremast and staysails between the masts, there is a gaff-rigged fore-and-aft sail, called a "spanker" or a "kicker" or sometimes a "mizzen". This sail occupies the lower to of the main or aftermost mast, with squares'ls above. * A full-rigged ship has three or more masts, including a foremast, mainmast and mizzen, and all masts are square-rigged. All the above rigs, except the single square sail, normally carry a number of jibs and generally carry fore-and-aft staysails between the masts.


Partially square-rigged types

* A
barquentine A barquentine or schooner barque (alternatively "barkentine" or "schooner bark") is a sailing vessel with three or more masts; with a square rigged foremast and fore-and-aft rigged main, mizzen and any other masts. Modern barquentine sailing ...
has three or more masts, typically with only the fore square-rigged while the main, mizzen and any others are
fore-and-aft A fore-and-aft rig is a sailing vessel rigged mainly with sails set along the line of the keel, rather than perpendicular to it as on a square rigged vessel. Description Fore-and-aft rigged sails include staysails, Bermuda rigged sails, gaf ...
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 schooner carries one or more square-rigged topsails on its foremast. This rig is often simply called a ''topsail schooner'' as topsails above the gaff-rigged sails are a standard part of the schooner rig. * 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.


See also

*
Glossary of nautical terms (A-L) This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water (mostly though not necessarily on the sea). Some remain current, while many date from the 17 ...
* Glossary of nautical terms (M-Z)


References


External links


Video: How the Square Rig Works
{{Sailing Vessels and Rigs, state=expanded Sailing rigs and rigging