A topsail is a sail set above another sail. On a square rigged vessel, a topsail is a square sail rigged above the course sail and below the topgallant sail where carried. A full rigged ship has either single or double topsails on all masts, the single or lower topsail being the second sail above the deck and the upper topsail where so rigged being the third. Although described as a "square" sail, this term refers not to a sail's shape but to it and its yard being rigged square to the keel of the vessel rather than in line with it or "fore and aft"; the bottom edge of the topsail, like that of other square sails, is concave. Although topsails of a kind were used at least as early as Roman times, they first came into use in Europe some time in the 15th century. Small and carried only on main and fore masts, they increased in size and importance until by the middle of the 17th century and were the principal and largest sails of the ship, the first sails to be set and the last to be taken in, it was quite common for a ship to sail with jibs alone.
The larger topsails were dangerous to handle in strong winds. Sometime in the 1680s, reef-bands were introduced to tie up part of the sail, with topsails getting four of these, reefing the sails became a regular occupation of sailors. In the mid 19th century, topsails of merchant vessels were split into separate upper and lower topsails that could be managed separately and far more by smaller crews. Competing versions of the double topsail were invented by Robert Bennet Forbes and Captain Frederic Howes. Although Forbes strove to defend his rig, the Howe rig dominated. In the Forbes rig, both topsail yards are fixed vertically. In the Howe rig, the upper topsail yard slides on the topmast so it can be lowered in a few seconds to close reef the upper topsail. Howe had the foot of the upper topsail attached to the lower topsail yard. In 1865 the British clipper Ariel introduced a gap there. Forbes first tried his rig in the topsail schooner Midas in 1844; the clipper Climax built in 1853 under the supervision of Howes was the first ship with Howe rig.
Gaff topsails, like gaff rigs in general, may still be seen at Tall Ships gatherings. The gaff rig has been superseded by the Bermuda rig, which has no topsails. On a gaff-rigged sailing boat, topsails may take a few different forms: A jib-headed topsail is a triangular sail set between the gaff and the top of the mast or topmast. A gaff-rigged vessel might have a gaff topsail above all of its gaff sails. A yard topsail set on a yard. Early 19th-century topsail yards were set horizontally, but increased in angle until they became vertical extension of the topmast. A jack-yard topsail instead has its lower edge extended out beyond the end of the gaff with a short yard, called a "jack-yard". A jack-yard topsail may have the aforementioned vertical yard, although this makes for a large topsail. A cornish topsail is a triangular sail having its luff extended well above the masthead by being laced to a yard hoisted by a halyard rove through a sheave fitted diagonally in the mast; the heel of the yard fits about the gaff and is kept in place by a tackline called a timminoggy.
A square topsail is a square-rigged sail, carried above the foresail only, on gaff schooners. Schooners carrying square tops are referred to as "topsail schooners". A raffee is a square-rigged topsail, triangular in shape; the use of the topsail in Thames sailing barges is different. It is a fore and aft rig. In confined waters, the barge will sail under topsail and mizzen, taking advantage of the clear air above the lee of the buildings; the topsail was attached by hoops to the topmast, so could be struck, the release of one rope let it fall. The topsail a fore and aft sail; the jib topsail a staysail set between the bowsprit. On rigs having multiple jibs or staysails of which at least one is set high, such as many late 19th and 20th Century racing cutters, the uppermost of these, set flying or on a topmast stay, is called the jib topsail. Topsails in the form of an isosceles triangle set above the square mainsail were used in Roman navigation. BibliographyMarch, Edgar J. Spritsail barges of the Medway.
London: Percival Marshall. John Harland & Mark Myers, Seamanship in the Age of Sail.
A genoa sail is a type of large jib or staysail that extends past the mast and so overlaps the main sail when viewed from the side, sometimes eliminating it. It was called an "overlapping jib" and a Genoa jib, it is used on twin-masted boats such as yawls and ketches. Its larger surface area increases the speed of the craft in light to moderate winds; the term jib is the generic term for any of an assortment of headsails. The term genoa refers to a type of jib, larger than the 100% foretriangle, the triangular area formed by the point at which the stay intersects the mast, deck or bowsprit, the line where the mast intersects deck at the rail. Colloquially the term is sometimes used interchangeably with jib. A working jib is no larger than the 100% foretriangle. A genoa is larger, with the leech overlapping the mainsail. To maximize sail area, the foot of the sail is parallel and close to the deck when close hauled. Genoas are categorized by a percentage representing their area relative to the 100% foretriangle.
Sail racing classes specify a limit to genoa size. Genoas are classified by their size. Number 2 genoas are in the range of 125–140%. Working jibs are defined by the same measure 100% or less of the foretriangle. Under Performance Handicap Racing Fleet rules, most boats are allowed 155% genoas without a penalty. Maximizing the sail area can cause more difficult handling, it may be harder to tack a genoa than a jib, since the overlapping area can become tangled with the shrouds and/or mast unless tended during the tack. Genoas are popular in some racing classes, since they count only the foretriangle area when calculating foresail size. In boats where sail restrictions do not apply, genoas of 180% overlap can be found, although those over 150% are rare because the additional area is shadowed by the mainsail when close hauled and generates diminishing returns in terms of power per actual sail area; the gennaker has been around for several decades now, as the name suggests, it is a hybrid between a genoa and a symmetrical spinnaker.
A brand name of North Sails, the gennaker started as a cruising sail based on the Code 0 spinnakers used on racing boats. Gennakers and similar code 0 variants offered by other makers are larger than genoas, they have a much greater camber for generating larger amounts of lift when reaching. Flat-cut gennakers can be effective for angles as low as 60–70 degrees. Spinnakers perform much better when running because the main sail blocks the wind of gennaker above 135–150 degrees; the famous Swedish sailor and shipowner Sven Salén first used the genoa on his 6 m R-yacht May-Be by the 1926 in Coppa di Terreno in Genoa, hence the name. He used it during the Scandinavian Gold Cup's races of 1927 in Oyster Bay. Sven Salén pioneered the parachute spinnacre. A similar type of jib was in use for centuries by the fishermen in the Netherlands with their Botter type ships; the fishermen relied on the combination of a large jib while fishing so the mainsail could remain unused. After fishing the fisherman's jib helped to get the fish to markets fast.
A correct explanation of the interaction between jib and mainsail was published by aerodynamicist and yachtsman Arvel Gentry in 1981, "is much more complicated than the old theories imply". This states that the believed explanation of the slot effect is "completely wrong" and shows that this is not due to the venturi effect accelerating the air in the slot. Instead it is shown that the air in the slot is slowed down and its pressure increased reducing the tendency of the mainsail to stall, that the mainsail reduces the air pressure on the lee side of the jib accelerating that airflow, that the mainsail increases the angle at which the air meets the luff of the jib, allowing the boat to point higher. Gentry points out that proper understanding of sail interaction allows better sail trimming
A lateen or latin-rig is a triangular sail set on a long yard mounted at an angle on the mast, running in a fore-and-aft direction. Dating back to Roman navigation, the lateen became the favorite sail of the Age of Discovery because it allows a boat to tack "against the wind." It is common in the Mediterranean, the upper Nile River, the northwestern parts of the Indian Ocean, where it is the standard rig for feluccas and dhows. The lateen is used today in a different form on small recreational boats like the Sailfish and Sunfish, but is still used as a working rig by coastal fishermen in the Mediterranean; the lateen evolved out of the dominant square rig by setting the sails more fore-and-aft – along the line of the keel – rather than athwartship, while tailoring the luff and leech. One theory is that the lateen sail originated during the early Roman empire in the Mediterranean Sea; the theory of Roman origin for lateen was first proposed by Lynn White and was elaborated upon by Lionel Casson.
Some scholars have proposed alternative explanations for the origins of the lateen. The political scientist John M. Hobson argues that some early passages interpreted by White as references to the lateen were only alluding to triangular topsails, expresses skepticism over early Byzantine depictions of lateen sails, he states that the long-distance seafaring of the Persians in the third and fourth centuries would have been impossible with square sails, so the lateen sail originated in Persia or Arabia and was introduced to the western Mediterranean region. However, such long distance sailing across the Indian Ocean was well established in the 1st century on the Hellenistic ships of Greco-Egyptian and Roman traders, as detailed in the Periplus of the Erythraean Sea. Historian George Hourani as well as specialists in the study of Austronesian cultures have instead suggested a Southeast Asian origin; the triangular shape of the lateen sail is characteristic of the far more ancient crab claw sails of the Austronesian sailors in the Indo-Pacific.
Some believe that early contact of Arab trade ships in the Indian Ocean with Austronesian sailors resulted in the development of the Arabic lateen sail. Arab ships are believed to have influenced the development of the Austronesian rectangular tanja sail, prevalent in western Southeast Asia. Austronesian sails, differ from western Eurasian sails in that they have spars along both the upper and lower edges. According to Lionel Casson, both types of lateen were known from an early date on: a 2nd-century AD gravestone depicts a quadrilateral lateen sail, while a 4th-century mosaic shows a triangular one, to become the standard rig throughout the Middle Ages. Casson argues that the earliest fore-and-aft rig was the spritsail, appearing in the 2nd century BC in the Aegean Sea on small Greek craft. According to the Belgian maritime historian Basch, the earliest lateen rig appears as early as the 1st century BC, in a wall painting found in a Hypogeum in Alexandria, Hellenistic Egypt. However, such an interpretation has been disputed.
The earliest archaeologically excavated lateen-rigged ship, the Yassi Ada II, dates to ca. 400 AD, with a further four being attested prior to the Arab advance to the Mediterranean. The Kelenderis ship mosaic and the Kellia ship graffito from the early 7th century complement the picture. By the 6th century, the lateen sail had replaced the square sail throughout the Mediterranean, the latter disappearing from Mediterranean iconography until the mid-13th century, it became the standard rig of the Byzantine dromon war galley and was also employed by Belisarius' flagship in the 532 AD invasion of the Vandal kingdom. After the Muslim conquests in Syria and North Africa, they adopted the lateen sail by way of the Coptic populace, which shared the existing Mediterranean maritime tradition and continued to provide the bulk of galley crews for centuries to come; this is indicated by the terminology of the lateen among Mediterranean Arabs, derived from Greco-Roman nomenclature. One theory suggests that the lateen sail was brought to the Indian Ocean by the Alexandrian merchants from Hellenistic Egypt and Roman Egypt who sailed the Red Sea in Roman and Byzantine and Arab times.
The emergence of evidence for the development and spread of the lateen sail in the ancient Mediterranean in recent decades has led to a reevaluation of the role of Roman and Arab seafaring in the Indian Ocean in that process, with some arguing that neither the attribution of the lateen to the Arabs nor its origin in the Indian Ocean can any longer be upheld: The origin of the lateen sail has been attributed by scholars to the Indian Ocean and its introduction into the Mediterranean traditionally ascribed to the Arab expansion of the early-7th century. This was due to the earliest iconographic depictions of lateen rigged ships from the Mediterranean post-dating the Islamic expansion into the Mediterranean basin... It was assumed that the Arab people who invaded the Mediterranean basin in the 7th century carried with them the sailing rig familiar to them; such theories have been superseded by unequivocal depictions of lateen-rigged Mediterranean sailing vessels which pre-date the Arab invasion.
Further inquiries into the appearance of the lateen rig in the Indian Ocean and its gulfs suggested a reversal of earlier scholarly opinion on the direction of diffusion, with Lynn White in 1978 arguing an introduction by Portuguese sailors in th
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 so rigged is called a square-rigger; the square rig is aerodynamically the most efficient running rig, stayed popular on ocean-going sailing ships until the end of the Age of Sail. The last commercial sailing ships, were square-rigged four-masted barques. Square-rigged masts may have triangular staysails that are deployed fore-and-aft between masts; the term "square-rigged" can describe individual, four-cornered sails suspended from the horizontal yards, carried on either a square-rigged or a fore-and-aft rigged vessel, such as one with a bermuda rigged or gaff rigged mainsail. "Square-rigged" is 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 reflects the fact that it was these men who managed the square-rigged sails. The peaked cap uniform worn by Senior Ratings 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 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. 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 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 under the wind.
18th-century warships would achieve tops speeds of 12–13 knots, 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; the late windjammers were as fast as the clippers. Not only could a smaller sail be managed by a smaller crew but 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 tear the whole larger area and reduce more of the vessel's motive power. With the development of more advanced fittings and cordage geared winches, high loads on an individual line became less of an issue, 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 enlarged the space available in the ship for profitable cargoes. New materials changed sail designs on hybrid vessels carrying some square-rigged sails; the low aspect ratio of square-rigged sails produces much drag for the lift produced, so they have poor performance to windward compared to modern yachts, they cannot sail as close to the wind.
The Bermuda rig is the undisputed champion of windward performance in soft sails, due to its low drag and high lift-to-drag ratio. One advantage of square rigs is that they are more efficient when running, where the high lift to drag is irrelevant and the total drag is the most important issue. Square-rigged sails are less prone to broaching when running than Bermuda rigs. Ocean-going vessels take advantage of prevailing winds such as the trade winds and the westerlies and are thus running. On a square-rigged mast, the sails had names; the lowest square sail was the course, the next sail up the mast was called the topsail, the next the topgallant sail. Many vessels shipped a fourth sail called the royal, above the other three, some 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. Sails are referred to by their mast and name, e.g. "the fore mast topgallant sail" shortened to "fore t'gallant", or "fore t'gar'ns'l".
Where no mast is specified, the main mast is implied. The oldest archaeological evidence of use of a square-rig on a vessel is an image on a clay disk from Mesopotamia from 5000BC. Single sail square rigs were used by the ancient Egyptians, the Phoenicians, the Greeks, the Romans, the Celts; the Scandinavians, the Germanic peoples, the Slavs adopted the single square-rigged sail, with it becoming one of the defining characteristics of the classic “Viking” ships. The early, simple square-rigged ships, having only the one square sail, were more limited in their ability to sail into the wind than multi-sail square-riggers. That, along with the vulnerability of a single large sail after guns began to be used in naval warfare, led to the single sail square rig being abandoned beginning in the medieval period, in favor of multi-sail, multi-mast square rigs. On multi-sail, multi-mast v
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 rotor ship is a type of ship designed to use the Magnus effect for propulsion. The ship is propelled, at least in part, by large vertical rotors, sometimes known as rotor sails. German engineer Anton Flettner was the first to build a ship which attempted to tap this force for propulsion, ships using his type of rotor are sometimes known as Flettner ships; the Magnus effect is a force acting on a spinning body in a moving airstream, which produces a force perpendicular to both the direction of the airstream and the axis of the rotor. A rotor or Flettner ship is designed to use the Magnus effect for propulsion; the Magnus effect is a force acting on a spinning body in a moving airstream, which acts perpendicular to both the direction of the airstream and of the rotor axis. A Magnus rotor is mounted with its axis vertical; when the wind blows from the side, the Magnus effect creates a forward thrust. Thus, as with any sailing ship, a rotor ship can only move forwards; the most common form of rotor sail is the Flettner rotor.
Due to the arrangement of forces, a rotor ship is able to sail closer to the wind than a conventional sailing ship. Other advantages include the ease of control from sheltered navigation stations and the lack of furling requirements in heavy weather; however if the ship changes tack so that the wind comes from the other side the direction of rotation must be reversed or the ship would be driven backwards. The wind does not power the rotor itself. Like other sailing ships, rotor ships have a small conventional propeller as well, to provide ease of manoeuvrability and forward propulsion at slow speeds and when the wind is not blowing or the rotor is stopped. In a hybrid rotor ship the propeller is the primary source of propulsion, while the rotor serves to offload it and thus increase overall fuel economy; the German engineer Anton Flettner was the first to build a ship which attempted to use the Magnus effect for propulsion. Assisted by Albert Betz, Jakob Ackeret, Ludwig Prandtl, Flettner constructed an experimental rotor vessel.
The vessel was a refitted schooner which carried two cylinders 15 metres high, 3 metres in diameter, driven by an electric propulsion system of 50 hp power. The Buckau sailed from Danzig to Scotland across the North Sea in February 1925; the ship could tack at 20–30 degrees, hence the rotors did not give cause for concern in stormy weather. The ship was renamed Baden Baden after the German spa town and on 31 March 1926 was sailed to New York via South America, arriving in New York Harbor on 9 May; the ship had proved inefficient on these voyages, with the power consumed by spinning 15m tall drums being disproportionate to the propulsive effect when compared with conventional propellers. As the system could not compete economically, Flettner turned his attention to other projects and the rotors were removed. In 1926, a larger ship with three rotors, the Barbara was built by the shipyard A. G. Weser in Bremen. Interest in rotor sails revived in the 1980s, as a way of increasing the fuel efficiency of a conventionally powered ship.
Enercon launched the hybrid rotor ship E-Ship 1 on 2 August 2008. From 2010 it has been used to transport the company's turbine other equipment. Enercon claim "operational fuel savings of up to 25% compared to same-sized conventional freight vessels."The University of Flensburg is developing the Flensburg catamaran or Uni-Cat Flensburg, a rotor-driven catamaran. In 2007, Stephen H. Salter and John Latham proposed the building of 1,500 robotic rotor ships to mitigate global warming; the ships would spray seawater into the air to enhance cloud reflectivity. A prototype rotor ship was tested on Discovery Project Earth; the rotors were made of carbon fibre and were attached to a retrofitted trimaran and propelled the vessel stably through the water at a speed of six knots. In 2009 Wärtsilä proposed a cruiseferry that would utilise Flettner rotors as a means of reducing fuel consumption; the Finnish ferry operator Viking Line adopted the idea, with MS Viking Grace built in 2011–2012 without rotors.
A rotor system was retrofitted in 2018. In 2014 and 2015 Norsepower installed twin rotor sails on Finnish shipping company Bore's RoRo vessel M/V Estraden. In May 2018 the 1996 built cargo ship Fehn Pollux of the German based Fehn Shipmanagement was fitted with an 18m long Flettner rotor of the EcoFlettner type at the front. In 2018 Norsepower started testing the rotor concept with the world's biggest shipping company, Maersk; the Maersk Pelican, an LR2 class tanker, has been fitted with two Norsepower Rotor Sails in readiness for trials. The MV Afros bulk carrier has operated 4 movable rotors over a year with good results. Turbosail Alcyone Wingsail Windmill ship Flettner rotor bomblet Rotor wing Center for the Study of Technology article Photograph of Baden Baden in NY harbour Bore to trial Norsepower Rotor Sail on Ro-Ro Propulsive power contribution of a kite and a Flettner rotor on selected shipping routes
A spinnaker pole is a spar used in sailboats to help support and control a variety of headsails the spinnaker. However, it is used with other sails, such as genoas and jibs, when sailing downwind with no spinnaker hoisted; the spinnaker pole is rigged to run from the base of the mast, where there is a special fitting for attaching one end of the pole, out to windward over the side of the boat. There, one of the control lines of whichever sail it is to be used with is run through a fitting on the other end of the spinnaker pole; this allows for more precise control of the corner of the sail. For a spinnaker, the line attached to the pole is the guy, or brace, the corner is the tack. For other headsails, such as a jib, the line would be the sheet, attached to the clew. A special line, the topping lift, runs from the middle of the spinnaker pole up to a block on the mast, is used to support the weight of the spinnaker pole. Another line referred to as the downhaul or foreguy runs down so that the height of the pole is under positive control at all times