Gaff rig is a sailing rig in which the sail is four-cornered, fore-and-aft rigged, controlled at its peak and its entire head by a spar called the gaff. Because of the size and shape of the sail, a gaff rig will have running backstays rather than permanent backstays; the gaff enables aft sail to be four sided, rather than triangular. A gaff rig carries 25 percent more sail than an equivalent bermudian rig for a given hull design. A sail hoisted from a gaff is called a gaff-rigged sail. Gaff rig remains the most popular fore-aft rig for schooner and barquentine mainsails and other course sails, spanker sails on a square rigged vessel are always gaff rigged. On other rigs the sloop and yawl, gaff rigged sails were once common but have now been replaced by the Bermuda rig sail, which, in addition to being simpler than the gaff rig allows vessels to sail closer to the direction from which the wind is blowing; the gaff is hoisted by two halyards: The throat halyard hoists the throat of the sail at the forward end of the gaff and bears the main weight of the sail and the tension of the luff.
The peak halyard bears the leech tension. Small craft attach the peak halyard to the gaff with a wire span with eyes at both ends looped around the gaff and held in place with small wooden chocks, larger craft have more than one span. Peak halyards pull upwards. Additionally, a gaff vang may be fitted, it is a line attached to the end of the gaff. Gaff vangs are difficult to rig on the aft-most sail, so are only found on schooners or ketches, only on the foresail or mainsail. A triangular fore-and-aft sail called a jib-headed topsail may be carried between the gaff and the mast. Gunter-rigged boats are similar, smaller vessels on which a spar is raised until it is nearly vertical, parallel to the mast and close adjacent to it. Topsails are never carried on gunter rigs; the Spritsail is another rig with a four-sided fore-aft sail. Unlike the gaff rig where the head hangs from a spar along its edge, this rig supports the leech of the sail by means of a spar named a sprit; the forward end of the sprit is attached to the mast but bisects the face of the sail, with the after end of the sprit attaching to the peak and/or the clew of the sail.
For a given sail area a gaff rig has a shorter mast than a bermudian rig. In short-ended craft with full body, heavy displacement and moderate ballast ratio, it is difficult to set enough sail area in the bermudian rig without a mast of excessive height and a center of effort too high for the limited stability of the hull; because of its low aspect ratio, the gaff rig is less prone to stalling if oversheeted than something taller and narrower. Whilst reaching, the CE being set further back, will encourage a small craft to bear up into the wind, i.e. strong weather helm. The boat builder can compensate for this at design stage, e.g. by shifting the keel aft, or having two jibs to counter the effect. The gaff-cutter is in fact a popular sailplan for small craft; the helmsman can reduce weather helm simply by sheeting out the mainsail. Sheeting out may appear to create an inefficient belly in the sail, but it is a pragmatic alternative to having a heavy helm. A swing keel lifted halfway is the perfect treatment for weather helm on a gaffer.
The usual adjustments to mast rake, or bowsprit length may be made to a gaffer with persistent heavy weather helm. On a gaff-rigged vessel, any heading where the wind is within 20 degrees of dead aft is considered a run; when running with a gaff-rig, the CE of the mainsail may be overboard of the hull, in a stiff wind the craft may want to broach. Running goose winged with a balloon staysail poled out to windward will balance the CE. In light winds, or when racing, a watersail may be set. Gunter Parts of a sail Spritsail Lug sail Rousmaniere, John; the Illustrated Dictionary of Boating Terms: 2,000 Essential Terms for Sailors & Powerboaters. W. W. Norton. ISBN 978-0-393-04649-6
The spritsail is a four-sided, fore-and-aft sail, supported at its highest points by the mast and a diagonally running spar known as the sprit. The foot of the sail can be held loose-footed just by its sheets. A spritsail has four corners: the throat, peak and tack; the Spritsail can be used to describe a rig that uses a spritsail. Spritsails were the first fore-and-aft rigs, appearing in Greco-Roman navigation in the 2nd century BC; the luff of the sail is bound to the mast, but unlike the gaff rig where the head is bound to a spar, this rig supports the leech of the sail by means of a diagonal spar or spars named a sprit. The forward end of the sprit spar is attached to the mast, with the after end of the sprit spar attached to the peak; the sprit is steadied and controlled from the deck by a pair of wire vangs attached to the peak of the sail. It is said to be the ancestor of the common gaff rig; the foot of the sail may be loose-footed and just controlled by its sheets. The spritsail was best known from its use in the Thames sailing barge, which employs two sized spars to form the framework for the sail area.
In a barge, the mast is stepped vertically in a mast case or tabernacle, whilst the sprit is suspended by chain stanliffs from the hounds at the mast head at an angle of about 30° from vertical, with sprit to the starboard side of the mast. The heel of the sprit is secured to the mast, by the muzzle, which allows the sprit is free to move laterally, nearly as far to each side as the shrouds; this enables the vessel to run. The instability caused by allowing such a weighty spar to extend too far away from the vessel's centreline, had to be borne in mind when designing hull and rigging; the peak of the sail is permanently attached to the head of the sprit, steadied by two sets of vangs. The spritsail rig was used without a boom; such loose-footed sails can be found on gaff-rigged Norfolk wherrys and the bawley class of vessel. The spritsail was a feature of the Cromster where the ability to furl the foot of the sail and raise the sheets, made gunnery much more possible; the sail could still be controlled using the vangs.
In a commercial vessel, the rig has the advantage of allowing a high stack of deck cargo and freeing the cargo hatch of obstructions when loading and unloading. The entire sail can be brailed to the mast; the overriding advantage is safety in open water. Barges will heel excessively and must be pulled to wind; the sheet will be eased and the aft end of a boom could drag in the water making the rudder ineffective and a capsize inevitable. The sheet of loose footed boomless barge is just released and control is regained; the boom does not project outboard so that the vessel can pass through a narrow gap between moored vessels. Loose footed sails suffer from sail twist which reduces their aerodynamic efficiency when sailing off the wind, not a commercial issue, it can be an advantage in light air. The vangs control the head of the sail which can be set so as to make use of the air above the wind-shadow of moored ships, warehouses and so on; this fine control of the sail without need for the crew to leave the deck, is achieved by brailing up.
Rather than lowering the mainsail, it is gathered up against its own luff and head by means of lines called brails. This technique is an effective way of stowing the mainsail and gives fine control over the power obtained from the sail. In narrow channels, in the lee of tall buildings the mailsail and mizzen are brailed and the bowsprit topped up, she sails on topsail and foresail alone. A gaff rig was far more suitable for heavy weather and long sea passages, but when a daff rigged boomie takes in the mainsail, she cannot set the topsail. However, it means, it means that the sail cannot be covered when it is stowed, thus protected from the elements. But in any case, the crews of working vessels did not trouble with such dainty ways. In keeping with the general philosophy of working boats, all sails would therefore be traditionally treated with red oxide and other substances; the problem of the inaccessibility of gear was met in the Thames barge by stepping the mast in a tabernacle and using a windlass on the foredeck to strike the whole lot, sprit and rigging.
The crew could sail under a low bridge such as at Aylesford or Rochester the without losing steerage way. The windlass is below the tack of the tackle at the foot of the forestay. In striking the gear, the foresail tack tackle had to be cast off, the bridge cleared, the skipper and an extra man used the windlass to raise the mast. Modern use of the spritsail has become more common through its use in the Optimist - this uses a boomed spritsail - in the case of which the sprit is tensioned by a snotter arrangement; this much simpler implementation sees the sprit anchored higher on the mast than on barges. This is a sprit rig that uses a triangular sail, the luff is bent to the mast, the one spar, the sprit-boom attaches to the clew of the sail; the fore end of the boom is tensioned by use of a snotter chord. On a Bolger 59 rig, there is 13' 7" leech and 9' 0" foot; the spiritsail is commonly used in a fore-and-aft rig on local traditional wooden boats of the west coast of Norway, most notably the faering variant of the Oselvar.
Traditionally, up until the second half of the 1
Rigging comprises the system of ropes and chains, which support a sailing ship or sail boat's masts—standing rigging, including shrouds and stays—and which adjust the position of the vessel's sails and spars to which they are attached—the running rigging, including halyards, braces and vangs. According to the Encyclopædia Britannica Eleventh Edition "rigging" derives from Anglo-Saxon wrigan or wringing, "to clothe"; the same source points out that "rigging" a sailing vessel refers to putting all the components in place to allow it to function, including the masts, spars and the rigging. Rigging is divided into two classes, which supports the mast, running, which controls the orientation of the sails and their degree of reefing. Configurations differ for each type of rigging, between fore-and-aft rigged vessels and square-rigged vessels. Standing rigging is cordage, fixed in position. Standing rigging is always between a mast and the deck, using tension to hold the mast in place. Due to its role, standing rigging is now most made of steel cable.
It was made of the same materials as running rigging, only coated in tar for added strength and protection from the elements. Most fore-and-aft rigged vessels have the following types of standing rigging: a forestay, a backstay, upper and lower shrouds. Less common rigging configurations are diamond jumpers. Both of these are used to keep a thin mast in column under the load of a large down wind sail or in strong wind. Rigging parts include swageless terminals, swage terminals, shackle toggle terminals and fail-safe wire rigging insulators. Whereas 20th-century square-rigged vessels were constructed of steel with steel standing rigging, prior vessels used wood masts with hemp-fiber standing rigging; as rigs became taller by the end of the 19th century, masts relied more on successive spars, stepped one atop the other to form the whole, from bottom to top: the lower mast, top mast, topgallant mast. This construction relied on support by a complex array of stays and shrouds; each stay in either the fore-and-aft or athwartships direction had a corresponding one in the opposite direction providing counter-tension.
Fore-and-aft the system of tensioning started with the stays that were anchored at in front each mast. Shrouds were tensioned by pairs deadeyes, circular blocks that had the large-diameter line run around them, whilst multiple holes allowed smaller line—lanyard—to pass multiple times between the two and thereby allow tensioning of the shroud. In addition to overlapping the mast below, the top mast and topgallant mast were supported laterally by shrouds that passed around either a platform, called a "top", or cross-wise beams, called "crosstrees"; each additional mast segment is supported aft by a series of stays that led forward. These lines were countered in tension by backstays, which were secured along the sides of the vessel behind the shrouds. Running rigging is the cordage used to control the shape and position of the sails. Materials have evolved from the use of Manilla rope to synthetic fibers, which include dacron and kevlar. Running rigging varies between fore-and-aft rigged vessels and square-rigged vessels.
They have common functions between them for supporting and orienting sails, which employ different mechanisms. For supporting sails, are used to raise sails and control luff tension. On gaff-rigged vessels, topping lifts hold the yards across the top of the sail aloft. Sail shape is controlled by lines that pull at the corners of the sail, including the outhaul at the clew and the downhaul at the tack on fore-and-aft rigs; the orientation of sails to the wind is controlled by sheets, but by braces, which position the yard arms with respect to the wind on square-rigged vessels. Full rigged ship John. Seamanship in the Age of Sail. Illus. by Mark Myers. Annapolis, Md: Naval Institute Press. ISBN 0-87021-955-3. OCLC 11036800. Lees, James; the Masting and Rigging of English Ships of War, 1625–1860. Annapolis, Md: Naval Institute Press. ISBN 0-87021-948-0. OCLC 11908132. Marchaj, C. A.. Aero-Hydrodynamics of Sailing. Saint Michaels, Md.: Tiller Publishing. ISBN 1-888671-18-1. OCLC 62546510. Marchaj, C. A.. Sail Performance: Theory and Practice.
Maidenhead, England: McGraw Hill. ISBN 0-07-141310-3. OCLC 51913243. Underhill, Harold A.. Masting and Rigging: The Clipper Ship and Ocean Carrier. Brill Academic Pub. ISBN 9780851741734. Photos of different types of ship rigging Sail Ship Rigging, at GlobalSecurity.org
In sailing, gaskets are lengths of rope or fabric used to hold a stowed sail in place. In modern use, the term is restricted to square-rigged ships, the equivalent items on yachts being referred to by the more prosaic "sail ties". On most ships, gaskets are made of rope, they are attached to the top of the yard and, left loose, would hang behind the sail. Gaskets should never be left dangling, however, so when the sail is set they are brought around underneath the yard and up the back of it and tied to the jackstay where they originated. Alternatively, longer gaskets - the clew gaskets described below - can be secured using a gasket coil; when the sail is to be stowed it is first folded and bagged neatly within itself, pulled onto the top of the yard, the gaskets are brought round over it and secured to the jackstay to hold it in place. Gaskets should be tied with a slippery hitch to enable them to be let off though if the yard is large there may only be enough rope to form a clove hitch when the gasket is brought round it.
Most ships are equipped with clew gaskets at the outer ends of the yards. These do not pass through a shackle or ring on the blocks of the sheet. Pulled tight and secured to the jackstay or the yard's lift, this takes the load off the clewline and sail, should allow the blocks to be lifted higher, dragging the sail down less and enabling a neater stow
Sail components include the features that define a sail's shape and function, plus its constituent parts from which it is manufactured. A sail may be classified in a variety of ways, including by its orientation to the vessel and its shape. Sails are constructed out of flexible material, shaped by various means, while in use, to offer an appropriate airfoil, according to the strength and apparent direction of the wind. A variety of features and fittings allow the sail to be attached to spars. Whereas conventional sails form an airfoil with one layer of fabric, wingsails comprise a structure that has material on both sides to form an airfoil—much like a wing placed vertically on the vessel—and are beyond the scope of this article. Sails may be classified as either triangular, which describes sails that either come to one point of suspension at the top or where the sail comes to a point at the forward end, or quadrilateral, which includes sails that are attached to a spar at the top and have three other sides, or as square.
They may be classified as symmetrical or asymmetrical. Asymmetrical sails perform better on points of sail closer to the wind than symmetrical sails and are designed for fore-and-aft rigs. Symmetrical sails perform best on points of sail. Triangular sails have names for each of three corners. Rigs with such sails include Bermuda, cutter and vessels with mixed sail plans that include jibs and other staysails. Most triangular sails are classified as fore and aft. Gaff, lug and some sprit sails have four sides and are set fore and aft so that one edge is leading into the wind, forming an asymmetric quadrilateral shape. Naming conventions are consistent with triangular sails, except for corners. A square rig is a 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—the sails themselves are not square but are symmetrically quadrilateral; these spars are called yards and their tips, beyond the last stay, are called the yardarms.
A ship so rigged is called a square-rigger. The shape of a sail is defined by its edges and corners in the plane of the sail, laid out on a flat surface; the edges may be curved, either to extend the sail's shape as an airfoil or to define its shape in use. In use, the sail becomes a curved shape, adding the dimension of draft; the top of all sails is called the head, the leading edge is called the luff, the trailing edge is the leech, the bottom edge is the foot. Head – The head is the upper edge of the sail, is attached at the throat and peak to a gaff, yard, or sprit. For a triangular sail the head refers to the topmost corner. Leech – The aft edge of a fore-and-aft sail is called the leech; the leech is either side edge of a symmetrical sail -- square. However, once a symmetrical sail has wind blowing along its surface, whether on a reach or close-hauled, the windward leech may be called a luff. Luff – The forward edge of a fore-and-aft sail is called the luff, may be attached along a mast or a stay.
When on a reach, the windward leech of a spinnaker is called the luff and, when on a reach or close-hauled, the windward leech of a square sail may be called the luff or the weather leech. Foot – The foot of a sail is its bottom edge. On a fore-and-aft mainsail, the foot is attached, at the tack and clew, to a boom. A fore-and-aft triangular mainsail achieves a better approximation of a wing form by extending the leech aft, beyond the line between the head and clew in an arc called the roach, rather than having a triangular shape; this added area would flutter in the wind and not contribute to the efficient airfoil shape of the sail without the presence of battens. Offshore cruising mainsails sometimes have a hollow leech to obviate the need for battens and their ensuing likelihood of chafing the sail. Roach is a term applied to square sail design—it is the arc of a circle above a straight line from clew to clew at the foot of a square sail, from which sail material is omitted; the roach allows the foot of the sail to clear stays coming up the mast, as the sails are rotated from side to side.
The names of corners of sails vary, depending on symmetry. Head – In a triangular sail, the corner where the luff and the leech connect is called the head. On a square sail, the top corners are head cringles. Peak – On a quadrilateral sail, the peak is the upper aft corner of the sail, at the top end of a gaff, a sprit or other spar. Throat – On a quadrilateral sail, the throat is the upper forward corner of the sail, at the bottom end of a gaff or other spar. Gaff-rigged sails, certain similar rigs, employ two halyards to raise the sails: the throat halyard raises the forward, throat end of the gaff, while the peak halyard raises the aft, peak end. Clew – The corner where the leech and foot connect is called the clew on a fore-and-aft sail. On a jib, the sheet is connected to the clew. Clews are the lower two corners of a square sail. Square sails have sheets attached to their clews like triangular sails, but the sheets are used to pull the sail down to the yard
A wingsail is a variable-camber aerodynamic structure, fitted to a marine vessel in place of conventional sails. Wingsails are analogous to airplane wings, except that they are designed to provide lift on either side to accommodate being on either tack. Whereas wings adjust camber with flaps, wingsails adjust camber with a flexible or jointed structure. Wingsails are mounted on an unstayed spar—often made of carbon fiber for lightness and strength; the geometry of wingsails provides more lift, a better lift-to-drag ratio, than traditional sails. Wingsails are more expensive than conventional sails. Wingsails are of two basic constructions that create an airfoil, "soft" and "hard". L. Francis Herreshoff pioneered a precursor rig that had jib and main, each with a two-ply sail with leading edges attached to a rotating spar; the C Class Catamaran class has been experimenting and refining wingsails in a racing context since the 60s. Englishman, John Walker, explored the use of wingsails in cargo ships and developed the first practical application for sailing yachts in the 1990s.
Wingsails have been applied to small vessels, like the Optimist dinghy and Laser, to cruising yachts, most notably to high-performance multihull racing sailboats, like USA-17. The smallest craft have a unitary wing, manually stepped. Cruising rigs have a soft rig. High-performance rigs are assembled of rigid components and must be stepped and unstepped by shore-side equipment. Wingsails change camber, depending on tack, wind speed. A wingsail becomes more efficient with greater curvature towards on the downwind side. Since the windward side changes with each tack, so must sail curvature change; this happens passively on a conventional sail. On a wingsail, a change in camber requires a mechanism. Wingsails change camber to adjust for windspeed. On an aircraft flaps increase the camber or curvature of the wing, raising the maximum lift coefficient—the lift a wing can generate—at a lower speeds of air passing over it. A wingsail has the same need for camber adjustment, as windspeed changes—a straighter camber curvature as windspeed increases, more curved as it decreases.
Mechanisms for camber adjustment are similar for hard wingsails. Each employs independent leading and trailing airfoil segments that are adjusted independently for camber. More sophisticated rigs allow for variable adjustment of camber with height above the water to account for increased windspeed; the presence of rigging, supporting the mast of a conventional fore-and-aft rig limits sail geometry to shapes that are less efficient than the narrow chord of the wingsail. However, conventional sails are simple to adjust for windspeed by reefing. Wingsails are a fixed surface area. Conventional sails can be furled easily. Nielsen summarised the efficiencies of wingsails, compared with conventional sails, for different points of sail, as follows: Close-hauled: At 30° apparent wind, the wingsail has a 10-degree angle of attack and more lift, compared to the conventional sail plan and its angles of attack of 15° for the jib and 20° for the mainsail. Beam reach: At 90° apparent wind, the wingsail, positioned across the boat, functions efficiently as a wing, providing forward lift, whereas the jib of the conventional sail plan suffers from being difficult to shape as a wing.
Broad reach: At 135° apparent wind, the wingsail may be eased in such a manner that it still functions efficiently as a wing, whereas the jib and main sail no longer provide lift—instead they present themselves perpendicular to the wind and provide force from drag only
A sail is a tensile structure—made from fabric or other membrane materials—that uses wind power to propel sailing craft, including sailing ships, windsurfers, ice boats, sail-powered land vehicles. Sails may be made from a combination of woven materials—including canvas or polyester cloth, laminated membranes or bonded filaments—usually in a three- or four-sided shape. A sail provides propulsive force via a combination of lift and drag, depending on its angle of attack—its angle with respect to the apparent wind. Apparent wind is the air velocity experienced on the moving craft and is the combined effect of the true wind velocity with the velocity of the sailing craft. Angle of attack is constrained by the sailing craft's orientation to the wind or point of sail. On points of sail where it is possible to align the leading edge of the sail with the apparent wind, the sail may act as an airfoil, generating propulsive force as air passes along its surface—just as an airplane wing generates lift—which predominates over aerodynamic drag retarding forward motion.
The more that the angle of attack diverges from the apparent wind as a sailing craft turns downwind, the more drag increases and lift decreases as propulsive forces, until a sail going downwind is predominated by drag forces. Sails are unable to generate propulsive force if they are aligned too to the wind. Sails may be attached to a mast, boom or other spar or may be attached to a wire, suspended by a mast, they are raised by a line, called a halyard, their angle with respect to the wind is controlled by a line, called a sheet. In use, they may be designed to be curved in both directions along their surface as a result of their curved edges. Battens may be used to extend the trailing edge of a sail beyond the line of its attachment points. Other non-rotating airfoils that power sailing craft include wingsails, which are rigid wing-like structures, kites that power kite-rigged vessels, but do not employ a mast to support the airfoil and are beyond the scope of this article. Sailing craft employ two types of the square rig and the fore-and-aft rig.
The square rig carries 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 so rigged is called a square-rigger; the square rig is aerodynamically most efficient. A fore-and-aft rig consists of sails that are set along the line of the keel rather than perpendicular to it. Vessels so rigged. Archaeological studies of the Cucuteni-Trypillian culture ceramics show use of sailing boats from the sixth millennium BCE onwards. Excavations of the Ubaid period in Mesopotamia provides direct evidence of sailing boats. Sails from ancient Egypt are depicted around 3200 BCE, where reed boats sailed upstream against the River Nile's current. Ancient Sumerians used square rigged sailing boats at about the same time, it is believed they established sea trading routes as far away as the Indus valley; the proto-Austronesian words for sail and other rigging parts date to about 3000 BCE when this group began their Pacific expansion.
Greeks and Phoenicians began trading by ship by around 1200 BCE. Triangular fore-and-aft rigs were invented in the Mediterranean as single-yarded lateen sails and independently in the Pacific as the more efficient bi-sparred crab claw sail, continue to be used throughout the world. During the 16th-19th centuries other fore-and-aft sails were developed in Europe, such as the spritsail, gaff rig, genoa and Bermuda rig mainsail, improving the upwind sailing ability of European vessels; the fore-and-aft rig began as a convention of southern Europe and the Mediterranean Sea: the gentle climate made its use practical, in Italy a few centuries before the Renaissance it began to replace the square rig which had dominated all of Europe since the dawn of sea travel. Northern Europeans were resistant to adopting the fore-and-aft rig, despite having seen its use in the course of trade and during the Crusades; the Renaissance changed this: beginning in 1475, their use increased and within a hundred years the fore-and-aft rig was in common use on rivers and in estuaries in Britain, northern France, the Low Countries, though the square rig remained standard for the harsher conditions of the open North Sea as well as for trans-Atlantic sailing.
The lateen sail proved to have better upwind performance for smaller vessels. Aerodynamic forces on sails depend on wind speed and direction and the speed and direction of the craft; the direction that the craft is traveling with respect to the true wind is called the "point of sail". The speed of the craft at a given point of sail contributes to the apparent wind —the wind speed and direction as measured on the moving craft; the apparent wind on the sail creates a total aerodynamic force, which may be resolved into drag—the force component in the direction of the apparent wind—and lift—the force component normal to the apparent wind. Depending on the alignment of the sail with the apparent wind, lift or drag may be the predominant propulsive component. Total aerodynamic force resolves into a forward, driving force—resisted by the medium through or over which the craft is passing —and a lateral force, resisted by the underwater foils, ice runners, or wheels of the sailing craft. For apparent wind angles aligned with the entry point of the sail, the sail acts as an airfoil and lift is the predominant component of propulsion.