Square rig

Square rig is a generic type of sailing vessel in which the main horizontal spars are perpendicular to the keel of the ship. These spars are called yardarms or simply yards. Square rig was the main design in the age of sail.

Related Topics:
Spar - Yardarms - Age of sail

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Square rig can also describe individual four-cornered sails suspended from yardarms, and 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.

Related Topics:
Sail - Bermuda rig - Gaff rig - Mainsail

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

A mast is considered square rigged if its 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.

Related Topics:
Mast - Course

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

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. The low aspect ratio of square rigged sails (usually 1/2 to 1/3) produce large amounts of drag for the lift they produce, and thus give very poor performance to windward. 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. Square rigs do have their advantages, however; they are more efficient when running, where the high lift to drag is irrelevent and the total lift is the most important issue. Not only do square rigged sails provide better downwind performance, but they also are less prone to broaching when running than bermuda rigs.

Related Topics:
Sloop - Full rigged ship - Gaff rig - Bermuda rig - Aspect ratio - Windward - Running - Broaching

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

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.

Related Topics:
Trapezoid - Foot - Head - Clew - Sheet - Blocks

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Modern square rigged ships are still used for training, tourism and ceremonial purposes.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~