Sail — Mediated Wiki

{{short description|Fabric or other surface supported by a mast to allow wind propulsion}} {{other uses}} {{multiple image  | align =  | direction = vertical | background color =  | width = 220 | caption_align = center  | header_background = | header_align =  | header =Sail rigs  | image1 = Chesapeake.jpg | caption1 = Square rigged frigate  | image2 = Sailing Vessel Odyssey.jpg | caption2 = Bermuda-rigged yawl.  | image3 = L-2013-Oracle-Team-USA-17.jpg | caption3 = Sailing hydrofoil catamaran with wingsail.  | footer_background = | footer_align =  | footer = }}

A '''sail''' is a tensile structure, which is made from fabric or other membrane materials, that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even 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 often 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 closely to the wind.

Sails may be attached to a mast, boom or other spar or may be attached to a wire that is suspended by a mast. They are typically raised by a line, called a ''halyard'', and their angle with respect to the wind is usually controlled by a line, called a sheet. In use, they may be designed to be curved in both directions along their surface, often 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, and kites that power kite-rigged vessels, but do not employ a mast to support the airfoil and are beyond the scope of this article.

==Rigs== {{Main|Square rig|Fore-and-aft rig}} Sailing craft employ two types of rig, the square rig and the fore-and-aft rig.

The ''square rig'' carries the primary driving sails 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 lifts, are called the ''yardarms<ref>Oxford English Dictionary</ref>''. A ship mainly so rigged is called a ''square-rigger''.<ref>{{cite book |last =Keegan |first =John |author-link =John Keegan |title =The Price of Admiralty |publisher =Viking |date =1989 |location =New York |page =[https://archive.org/details/priceofadmiralty00keeg/page/280 280] |isbn =0-670-81416-4 |url =https://archive.org/details/priceofadmiralty00keeg/page/280 }}</ref>

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 are described as ''fore-and-aft rigged''.<ref>{{Cite book | last = Knight | first = Austin Melvin | title = Modern seamanship | publisher = D. Van Nostrand | year = 1910 | location = New York | pages = 507–532 }}</ref>

==History== thumb|Egyptian sailing ship, ca. 1422–1411 BCE {{Main|Ship#History}} The invention of the sail was a technological advance of equal or even greater importance than the invention of the wheel.{{efn|The wheel was invented {{circa}}5,000BCE {{r|Jett 2017|p=174}}}} It has been suggested by some that it has the significance of the development of the Neolithic lifestyle or the first establishment of cities. Yet it is not known when or where this invention took place.<ref name="Jett 2017">{{cite book |last1=Jett |first1=Stephen C. |title=Ancient ocean crossings: reconsidering the case for contacts with the pre-Columbian Americas |date=2017 |publisher=The University of Alabama Press |location=Tuscaloosa |isbn=978-0-8173-9075-4}}</ref>{{rp|173}}

Much of the early development of water transport is believed to have occurred in two main "nursery" areas of the world: Island Southeast Asia and the Mediterranean region. In both of these, warmer waters reduce the risk of hypothermia when using rafts (a raft is usually a "flow through" structure), and a number of intervisible islands create both an invitation to travel and an environment where advanced navigation techniques are not needed. Alongside this, the Nile has a northward flowing current with a prevailing wind in the opposite direction, so giving the potential to drift in one direction and sail in the other.<ref name="McGrail 2014a">{{cite book |last1=McGrail |first1=Sean |title=Early ships and seafaring : European water transport |date=2014 |publisher=Pen and Sword Archaeology |location=South Yorkshire, England |isbn=9781781593929}}</ref>{{rp|113}}<ref name="McGrail 2014b">{{cite book |last1=McGrail |first1=Sean |title=Early ships and seafaring : water transport beyond Europe |date=2014 |publisher=Pen and Sword Books Limited |location=Barnsley |isbn=9781473825598}}</ref>{{rp|7}} Many do not consider sails to have been used before the 5th millennium BCE. Others consider sails to have been invented much earlier.{{r|Jett 2017|p=174, 175}}

Archaeological studies of the Cucuteni-Trypillian culture ceramics show use of sailing boats from the sixth millennium BCE onwards.<ref name=Gimbutas>{{cite book|last=Gimbutas|first=Marija|title=The goddesses and gods of Old Europe, 6500–3500 BCE: myths and cult images|year=2007|publisher=University of California Press|location=Berkeley|isbn=978-0-520-25398-8|page=18|edition=New and updated|chapter=1|quote=The use of sailing-boats is attested from the sixth millennium onwards by their incised depiction on ceramics.}}</ref> Excavations of the Ubaid period (c. 6000–4300 BCE) in Mesopotamia provide direct evidence of sailing boats.<ref name=Carter>{{cite book|last=Carter|first=Robert|title=A companion to the archaeology of the ancient Near East. Ch 19 Watercraft|publisher=Wiley-Blackwell|location=Chichester, West Sussex|isbn=978-1-4051-8988-0|pages=347–354|url=https://www.academia.edu/1576775|author-link=Watercraft|editor=Potts, D.T.|access-date=8 February 2014|chapter=19|year=2012|url-status=live|archive-url=https://web.archive.org/web/20150428190743/http://www.academia.edu/1576775/Watercraft|archive-date=28 April 2015}}</ref>

===Square rigs=== Sails from ancient Egypt are depicted around 3200 BCE,<ref name=qaa>{{cite web|publisher=Yale|year=2006|title=The Wadi of the Horus Qa-a: A Tableau of Royal Ritual Power in the Theban Western Desert |author=John Coleman Darnell |url=http://www.yale.edu/egyptology/ae_alamat_wadi_horus.htm |access-date=2010-08-24 |url-status=dead |archive-url=https://web.archive.org/web/20110201053044/http://www.yale.edu/egyptology/ae_alamat_wadi_horus.htm|archive-date=2011-02-01}}</ref><ref name=johnstone>The sea-craft of prehistory, p76, by Paul Johnstone, Routledge, 1980</ref> where reed boats sailed upstream against the River Nile's current. Ancient Sumerians used square rigged sailing boats at about the same time, and it is believed they established sea trading routes as far away as the Indus valley. Greeks and Phoenicians began trading by ship by around 1200 BCE.

V-shaped square rigs with two spars that come together at the hull were the ancestral sailing rig of the Austronesian peoples before they developed the fore-and-aft crab claw, tanja and junk rigs.<ref name="Campbell">{{cite journal |last1=Campbell |first1=I.C. |title=The Lateen Sail in World History |journal=Journal of World History |date=1995 |volume=6 |issue=1 |pages=1–23 |jstor=20078617 |url=https://www.jstor.org/stable/20078617 |access-date=2022-06-03 |archive-date=2023-06-06 |archive-url=https://web.archive.org/web/20230606060833/https://www.jstor.org/stable/20078617 |url-status=live }}</ref> The date of introduction of these later Austronesian sails is disputed.<ref name="Anderson 2018">{{cite book |last1=Anderson |first1=Atholl |editor1-last=Cochrane |editor1-first=Ethan E |editor2-last=Hunt |editor2-first=Terry L. |title=The Oxford handbook of prehistoric Oceania |date=2018 |location=New York, NY |isbn=978-0-19-992507-0 |chapter=SEAFARING IN REMOTE OCEANIA Traditionalism and Beyond in Maritime Technology and Migration}}</ref>

===Lateen rigs=== [[File:Bgl3t.jpg|thumb|A traditional Maldivian Baghlah with a fore-and-aft rig lateen rig]] {{Main|Lateen|Fore-and-aft rig}} Lateen sails emerged by around the 2nd century CE in the Mediterranean. They did not become common until the 5th century, when there is evidence that the Mediterranean square sail (which had been in wide use throughout the classical period) was undergoing a simplification of its rigging components.{{efn|An obvious component of the Mediterranean square sail in archaeological situations are the lead rings through which brail lines were led. The brails were used to reduce sail area in rising winds. The cheaper alternative was to use reefing points (as is seen in traditional sailing craft of today), with the archaeological record seeing a disappearance of the distinctive lead rings.}} Both the increasing popularity of the lateen and the changes to the contemporary square rig are suggested to be cost saving measures, reducing the number of expensive components needed to fit out a ship.<ref name="Whitewright 2012a">{{cite journal |last1=Whitewright |first1=Julian |title=Technological Continuity and Change: The Lateen Sail of the Medieval Mediterranean |journal=Al-Masāq |date=April 2012 |volume=24 |issue=1 |pages=1–19 |doi=10.1080/09503110.2012.655580|s2cid=161464823 }}</ref>

It has been a common and erroneous presumption among maritime historians that lateen had significantly better sailing performance than the square rig of the same period. Analysis of voyages described in contemporary accounts and also in various replica vessels demonstrates that the performance of square rig and lateen were very similar. Lateen provided a cheaper rig to build and maintain, with no degradation of performance.<ref name="Whitewright 2011">{{cite journal |last1=Whitewright |first1=Julian |title=The Potential Performance of Ancient Mediterranean Sailing Rigs: THE POTENTIAL PERFORMANCE OF ANCIENT MEDITERRANEAN SAILING RIGS |journal=International Journal of Nautical Archaeology |date=March 2011 |volume=40 |issue=1 |pages=2–17 |doi=10.1111/j.1095-9270.2010.00276.x|bibcode=2011IJNAr..40....2W |s2cid=111007423 }}</ref>{{r|Whitewright 2012a}}

The lateen was adopted by Arab seafarers (usually in the sub-type: the settee sail), but the date is uncertain, with no firm evidence for their use in the Western Indian Ocean before 1500 CE. There is, however, good iconographic evidence of square sails being used by Arab, Persian and Indian ships in this region in, for instance, 1519.<ref name="Vosmer 2014">{{cite book |last1=Vosmer |first1=Tom |editor1-last=Sindbæk |editor1-first=Søren |editor2-last=Trakadas |editor2-first=Athena |title=The world in the viking age |date=2014 |publisher=The Viking Ship Museum in Roskilde |location=Roskilde |isbn=9788785180704 |chapter=The Belitung shipwreck and Jewel of Muscat}}</ref>

The popularity of the caravel in Northern European waters from about 1440 made lateen sails familiar in this part of the world. Additionally, lateen sails were used for the {{nautical term|mizzen}} on early three-masted ships, playing a significant role in the development of the full-rigged ship. It did not, however, provide much of the propulsive force of these vessels – rather serving as a balancing sail that was needed for some manoeuvres in some sea and wind conditions. The extensive amount of contemporary maritime art showing the lateen mizzen on 16th and 17th century ships often has the sail furled. Practical experience on the ''Duyfken'' replica confirmed the role of the lateen mizzen.<ref name="Burningham 2001">{{cite journal |last1=Burningham |first1=Nick |title=Learning to sail the Duyfken replica |journal=International Journal of Nautical Archaeology |date=April 2001 |volume=30 |issue=1 |pages=74–85 |doi=10.1111/j.1095-9270.2001.tb01357.x|bibcode=2001IJNAr..30...74B }}</ref><ref name="Elbl 1994">{{cite book |last1=Elbl|first1=Martin |editor1-last=Gardiner |editor1-first=Robert |editor2-last=Unger |editor2-first=Richard W |title=Cogs, Caravels and Galleons : the sailing ship, 1000-1650 |date=1994 |publisher=Conway Maritime Press |location=London |isbn=0851775608 |chapter=The Caravel and the Galleon}}</ref> <ref name="Friel 1994">{{cite book |last1=Friel|first1=Ian|editor1-last=Gardiner |editor1-first=Robert |editor2-last=Unger |editor2-first=Richard W |title=Cogs, Caravels and Galleons : the sailing ship, 1000-1650 |date=1994 |publisher=Conway Maritime Press |location=London |isbn=0851775608 |chapter=The Carrack – the advent of the full rigged ship}}</ref>

===Crab claw rigs=== {{Main|Crab claw sail|Fore-and-aft rig}} [[File:Atlas pittoresque pl 096.jpg|thumb|upright|Fijian voyaging outrigger boat with a crab claw sail]] [[File:Iranun Lanong warship by Rafael Monleón (1890).jpg|thumb|upright|Philippine ''lanong'' with tanja sails]] Austronesian invention of catamarans, outriggers, and the bi-sparred triangular crab claw sails enabled their ships to sail for vast distances in open ocean. It led to the Austronesian Expansion. From Taiwan, they rapidly settled the islands of Maritime Southeast Asia, then later sailed further onwards to Micronesia, Island Melanesia, Polynesia, and Madagascar, eventually settling a territory spanning half the globe.<ref name="Doran1974">{{cite journal |last1=Doran |first1=Edwin Jr. |title=Outrigger Ages |journal=The Journal of the Polynesian Society |date=1974 |volume=83 |issue=2 |pages=130–140 |url=http://www.jps.auckland.ac.nz/document//Volume_83_1974/Volume_83%2C_No._2/Outrigger_ages%2C_by_Edwin_Doran_Jnr.%2C_p_130-140/p1 |access-date=2019-10-16 |archive-date=2019-06-08 |archive-url=https://web.archive.org/web/20190608182436/http://www.jps.auckland.ac.nz/document/Volume_83_1974/Volume_83,_No._2/Outrigger_ages,_by_Edwin_Doran_Jnr.,_p_130-140/p1 |url-status=live }}</ref><ref name="Mahdi1999">{{cite book|first1= Waruno|last1=Mahdi|editor1-last =Blench|editor1-first= Roger |editor2-last=Spriggs|editor2-first=Matthew|title =Archaeology and Language III: Artefacts languages, and texts|chapter =The Dispersal of Austronesian boat forms in the Indian Ocean|volume = 34|publisher =Routledge|series =One World Archaeology |year =1999|pages=144–179|isbn =978-0-415-10054-0}}{{dead link|date=February 2020}}</ref>

The proto-Austronesian words for sail, ''lay(r)'', and some other rigging parts date to about 3000 BCE when this group began their Pacific expansion.<ref name=Lewis1>{{cite book|last=Lewis|first=David|title=We, the Navigators : the ancient art of landfinding in the Pacific|year=1994|publisher=University of Hawaii Press|location=Honolulu|isbn=0-8248-1582-3|page=[https://archive.org/details/wenavigatorsanci0000lewi/page/7 7]|edition=2nd}}</ref> Austronesian rigs are distinctive in that they have spars supporting both the upper and lower edges of the sails (and sometimes in between).<ref name="Mahdi1999" /> The sails were also made from salt-resistant woven leaves, usually from pandan plants.<ref name="Kirch2012">{{cite book|first1=Patrick Vinton|last1=Kirch|title =A Shark Going Inland Is My Chief: The Island Civilization of Ancient Hawai'i|publisher =University of California Press|year =2012|pages=25–26|isbn = 978-0-520-95383-3|url =https://books.google.com/books?id=CDQy8OOicF4C&pg=PA25}}</ref><ref name="Gallaher2014">{{cite book|first1=Timothy|last1=Gallaher|editor1-first=Lia O'Neill M.A.|editor1-last=Keawe|editor2-first=Marsha|editor2-last=MacDowell|editor3-first=C. Kurt|editor3-last=Dewhurst|title =ʻIke Ulana Lau Hala: The Vitality and Vibrancy of Lau Hala Weaving Traditions in Hawaiʻi|chapter =The Past and Future of Hala (''Pandanus tectorius'') in Hawaii|publisher =Hawai'inuiakea School of Hawaiian Knowledge; University of Hawai'i Press |year =2014|doi= 10.13140/RG.2.1.2571.4648|isbn =978-0-8248-4093-8 |chapter-url =https://www.researchgate.net/publication/276291081}}</ref>

Crab claw sails used with single-outrigger ships in Micronesia, Island Melanesia, Polynesia, and Madagascar were intrinsically unstable when tacking leeward. To deal with this, Austronesians in these regions developed the shunting technique in sailing, in conjunction with uniquely reversible single-outriggers. In the rest of Austronesia, crab claw sails were mainly for double-outrigger (trimarans) and double-hulled (catamarans) boats, which remained stable even leeward.<ref name="Mahdi1999"/><ref name="Doran1981">{{cite book |last1=Doran |first1=Edwin B. |title=Wangka: Austronesian Canoe Origins |date=1981 |publisher=Texas A&M University Press |isbn=978-0-89096-107-0}}</ref><ref name="Doran1974"/><ref name="Beheim">{{cite journal |last1=Beheim |first1=B. A. |last2=Bell |first2=A. V. |title=Inheritance, ecology and the evolution of the canoes of east Oceania |journal=Proceedings of the Royal Society B: Biological Sciences |date=23 February 2011 |volume=278 |issue=1721 |pages=3089–3095 |doi=10.1098/rspb.2011.0060|pmid=21345865 |pmc=3158936 }}</ref><ref name="Hornell1932">{{cite journal |last1=Hornell |first1=James |date=1932 |title=Was the Double-Outrigger Known in Polynesia and Micronesia? A Critical Study |journal=The Journal of the Polynesian Society |volume=41 |issue=2 (162) |pages=131–143 |jstor=20702413}}</ref>

In western Island Southeast Asia, later square sails also evolved from the crab claw sail, the tanja and the junk rig, both of which retained the Austronesian characteristic of having more than one spar supporting the sail.<ref name="Hourani 1951">{{Cite book|title=Arab Seafaring in the Indian Ocean in Ancient and Early Medieval Times|last=Hourani|first=George Fadlo|publisher=Princeton University Press|year=1951|location=New Jersey}}</ref><ref name="Johnstone 1980">{{Cite book|title=The Seacraft of Prehistory|last=Johnstone|first=Paul|publisher=Harvard University Press|year=1980|isbn=978-0-674-79595-2|location=Cambridge}}</ref>

==Aerodynamic forces== thumb|right|Aerodynamic forces for two points of sail. ''Left-hand boat'': Down wind—predominant ''drag'' propels the boat with little heeling moment. ''Right-hand boat'': Up wind (close-hauled)—predominant ''lift'' both propels the boat and contributes to heel. [[File:Sail angles of attack and resulting flow patterns.jpg|thumb|right|Sail angles of attack and resulting (idealized) flow patterns that provide propulsive lift.]] {{Main|Forces on sails}} 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'' (the wind direction and speed over the surface) is called the "point of sail". The speed of the craft at a given point of sail contributes to the apparent wind ('''VA'''), 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 (90°) 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 also resolves into a forward, propulsive, driving force, resisted by the medium through or over which the craft is passing (e.g., through water, air, or over ice, sand) and a lateral force, resisted by the underwater foils, ice runners, or wheels of the sailing craft.<ref name = Clancy> {{Citation | last = Clancy | first = L.J. | title = Aerodynamics | place = London | publisher = Pitman Publishing Limited | year = 1975 | pages = 638 | isbn = 0-273-01120-0 }}</ref>

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. For apparent wind angles behind the sail, lift diminishes and drag increases as the predominant component of propulsion. For a given true wind velocity over the surface, a sail can propel a craft to a higher speed, on points of sail when the entry point of the sail is aligned with the apparent wind, than it can with the entry point not aligned, because of a combination of the diminished force from airflow around the sail and the diminished apparent wind from the velocity of the craft. Because of limitations on speed through the water, displacement sailboats generally derive power from sails generating lift on points of sail that include close-hauled through broad reach (approximately 40° to 135° off the wind).<ref name=Jobson2>{{cite book | last = Jobson | first = Gary | title = Championship Tactics: How Anyone Can Sail Faster, Smarter, and Win Races | publisher = St. Martin's Press | location = New York | year = 1990 | isbn = 0-312-04278-7 | pages = [https://archive.org/details/championshiptact00jobs/page/323 323] | url = https://archive.org/details/championshiptact00jobs/page/323 }}</ref> Because of low friction over the surface and high speeds over the ice that create high apparent wind speeds for most points of sail, iceboats can derive power from lift further off the wind than displacement boats.<ref> {{cite book |last = Bethwaite |first = Frank |title = High Performance Sailing |publisher = Adlard Coles Nautical |year = 2007 |isbn = 978-0-7136-6704-2}}</ref> {{center| ;Downwind sailing with a spinnaker }} <gallery mode="packed" heights="150px"> File:Sailboat on broad reach with spinnaker.jpg|Spinnaker set for a broad reach, mobilizing both lift and drag. File:Spinnaker trimmed for broad reach.jpg|Spinnaker cross-section trimmed for a broad reach showing air flow. File:Amante Choate 48 photo D Ramey Logan.jpg|Spinnaker downwind, primarily mobilizing drag. File:Symmetrical spinnaker with following apparent wind.jpg|Spinnaker cross-section with following apparent wind, showing air flow. </gallery>

==Types== thumb|upright=1.35|Different sail types.<ref>Clerc-Rampal, G. (1913) Mer : la Mer Dans la Nature, la Mer et l'Homme, Paris: Librairie Larousse, p. 213</ref> {{col-begin}} {{col-break}} A. Course B. Topsail C. Lateen D. Staysail {{col-break}} E. Gaff-rigged G. Quadrilateral H. Loose-footed J. Spritsail {{col-break}} K. Standing lug L. Triangular M. Dipping lug N. Junk {{col-end}} {{See also|Sail plan}} Each rig is configured in a ''sail plan'', appropriate to the size of the sailing craft. A sail plan is a set of drawings, usually prepared by a naval architect which shows the various combinations of sail proposed for a sailing ship. Sail plans may vary for different wind conditions—light to heavy. Both square-rigged and fore-and-aft rigged vessels have been built with a wide range of configurations for single and multiple masts with sails and with a variety of means of primary attachment to the craft, including:<ref name=Folkard> {{cite book |last = Folkard |first = Henry Coleman |title = Sailing Boats from Around the World: The Classic 1906 Treatise |publisher = Courier Corporation |series = Dover Maritime |date = 2012 |pages = 576 |url = https://books.google.com/books?id=_am8AQAAQBAJ&q=Sail+plan&pg=PR15 |isbn = 978-0-486-31134-0 |url-status = live |archive-url = https://web.archive.org/web/20171111191644/https://books.google.com/books?id=_am8AQAAQBAJ&pg=PR15&dq=Sail+plan&hl=en&sa=X&ved=0ahUKEwjz2rHsnMLRAhVCOiYKHZcTD78Q6AEILTAD#v=onepage&q=Sail%20plan&f=false |archive-date = 2017-11-11 }}</ref> *Jibs, which are usually attached to forestays, and staysails, which are mounted on other stays (typically wire cable) that support other masts from the bow aft. *Gaff-rigged quadrilateral and Bermuda triangular sails, fore-and-aft sails directly attached to the mast at the luff. *Square sails and such fore-and-aft quadrilateral sails as lug rigs, junk and spritsails and such triangular sails as the lateen, and the crab claw have their primary attachment to the vessel via a spar. *Symmetrical spinnakers' primary attachment to a vessel is by a halyard.

High-performance yachts, including the International C-Class Catamaran, have used or use rigid ''wing sails'', which perform better than traditional soft sails but are more difficult to manage.<ref name=Sail> {{cite magazine |last = Nielsen |first = Peter |title = Have Wingsails Gone Mainstream? |magazine = Sail |date = May 14, 2014 |url = http://www.sailmagazine.com/boats/have-wingsails-gone-mainstream |access-date = 2015-01-24 |url-status = live |archive-url = https://web.archive.org/web/20150412203330/http://www.sailmagazine.com/boats/have-wingsails-gone-mainstream |archive-date = April 12, 2015 }}</ref> A rigid wing sail was used by ''Stars and Stripes'', the defender which won the 1988 America's Cup, and by ''USA-17'', the challenger which won the 2010 America's Cup.<ref> {{cite news |url = http://www.iht.com/articles/ap/2008/11/07/sports/SAI-Americas-Cup-Big-Boat.php |title = America's cup: BMW Oracle Racing pushes edge in 90-foot trimaran |date = 2008-11-08 |newspaper = International Herald Tribune |access-date = 2009-03-07 |url-status = live |archive-url = https://web.archive.org/web/20081211173314/http://www.iht.com/articles/ap/2008/11/07/sports/SAI-Americas-Cup-Big-Boat.php |archive-date = 2008-12-11 }}</ref> ''USA 17'''s performance during the 2010 America's Cup races demonstrated a velocity made good upwind of over twice the wind speed and downwind of over 2.5 times the wind speed and the ability to sail as close as 20 degrees off the apparent wind.<ref> {{cite web |url = http://www.cupinfo.com/en/bmwo-multihull-san-diego-coutts-002.php |title = Russell Coutts Talks About BMW Oracle's Giant Multi-hull |last = Swintal |first = Diane |date = 13 August 2009 |work = cupinfo.com |access-date = 2012-04-25 |url-status = live |archive-url = https://web.archive.org/web/20120217023810/http://www.cupinfo.com/en/bmwo-multihull-san-diego-coutts-002.php |archive-date = 17 February 2012 }}</ref>

==Shape== thumb|right|Corners and sides of a quadrilateral fore-and-aft sail {{main|Sail components#Shape}}

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 depth or ''draft''. *''Edges'' – The top of all sails is called the ''head'', the leading edge is called the ''luff'' on fore-and-aft sails<ref name="SAIL Magazine 101" /> and on windward leech symmetrical sails, the trailing edge is the ''leech'', and the bottom edge is the ''foot''. The ''head'' is attached at the throat and peak to a gaff, yard, or sprit.{{sfn|King|Hattendorf|Estes|2000|page=283}} For a triangular sail the ''head'' refers to the topmost corner.<ref name="SAIL Magazine 101" /> :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 on 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.<ref name=Textor> {{cite book |last = Textor |first = Ken |title = The New Book of Sail Trim |publisher = Sheridan House, Inc. |date = 1995 |url = https://books.google.com/books?id=2JIbS0c1XPwC&q=downwind+sailing&pg=PA50 |pages = 228 |isbn = 0-924486-81-3 |url-status = live |archive-url = https://web.archive.org/web/20160517224802/https://books.google.com/books?id=2JIbS0c1XPwC&pg=PA50&dq=downwind+sailing&hl=en&sa=X&ei=LoggVeSSCsvlsAX2oIDICA&ved=0CB4Q6AEwAA#v=onepage&q=downwind%20sailing&f=false |archive-date = 2016-05-17 }} </ref> Offshore cruising mainsails sometimes have a ''hollow leech'' (the inverse of a roach) to obviate the need for battens and their ensuing likelihood of chafing the sail.<ref name=Nicolson> {{cite book |last = Nicolson |first = Ian |title = A Sail for All Seasons: Cruising and Racing Sail Tips |publisher = Sheridan House, Inc. |date = 1998 |pages = 124 |url = https://books.google.com/books?id=nO3M-8JAhH4C&q=leech+line+sail&pg=PA93 |isbn = 978-1-57409-047-5 |url-status = live |archive-url = https://web.archive.org/web/20171111191644/https://books.google.com/books?id=nO3M-8JAhH4C&pg=PA93&dq=leech+line+sail&hl=en&sa=X&ved=0ahUKEwizvaGQzL3RAhVJNSYKHWnFA7YQ6AEIGjAA#v=onepage&q=leech%20line%20sail&f=false |archive-date = 2017-11-11 }}</ref> The roach on a square sail design is the arc of a circle above a straight line from clew to clew at the foot of a square sail, which allows the foot of the sail to clear stays coming up the mast, as the sails are rotated from side to side.<ref name="Kipping1847"/>

*''Corners'' – The names of corners of sails vary, depending on shape and symmetry. In a triangular sail, the corner where the luff and the leech connect is called the ''head''.<ref name=Jobson>{{cite book |last = Jobson |first = Gary |title = Sailing Fundamentals |publisher = Simon and Schuster |edition = Revised |date = 2008 |location = New York |pages = 224 |url = https://books.google.com/books?id=mKTrrP3wA-cC&q=Sail+terminology |isbn = 978-1-4391-3678-2 |url-status = live |archive-url = https://web.archive.org/web/20171111191644/https://books.google.com/books?id=mKTrrP3wA-cC&printsec=frontcover&dq=Sail+terminology&hl=en&sa=X&ved=0ahUKEwiF-JHs7YrPAhVGVz4KHYr_BSEQ6AEIMDAD#v=onepage&q=Head&f=false |archive-date = 2017-11-11 }}</ref><ref name="SAIL Magazine 101">{{cite web |author1= |title=Know How: Sailing 101 |url=http://www.sailmagazine.com/cruising/cruising-tips/basic-sailing-101/ |url-status=live |archive-url=https://web.archive.org/web/20161005070356/http://www.sailmagazine.com/cruising/cruising-tips/basic-sailing-101/ |archive-date=5 October 2016 |access-date=4 October 2016 |work=Sail Magazine |date=26 September 2016 |language=en}}</ref> On a square sail, the top corners are ''head cringles'', where there are grommets, called cringles.<ref name = Knight> {{cite book | last = Knight | first = Austin N. | title = Modern Seamanship | publisher = D. van Nostrand Company | edition = 8 | date = 1921 | location = New York | pages = [https://archive.org/details/modernseamanshi00kniggoog/page/n850 831] | url = https://archive.org/details/modernseamanshi00kniggoog | quote = head cringle. }}</ref> On a quadrilateral sail, the ''peak'' is the upper aft corner of the sail, at the top end of a gaff or other spar. The ''throat'' is the upper forward corner of the sail, at the bottom end of a gaff or other spar. Gaff-rigged sails, and 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.<ref name=Hattendorf>{{cite book|last1=King|first1=Dean|first2=John B.|last2=Hattendorf|first3=J W.|last3=Estes|title=A sea of words: a lexicon and companion for Patrick O'Brian's seafaring tales|location=New York|date=2000|publisher=Henry Holt|url=https://books.google.com/books?id=BK-PyCrQ0aMC&q=King,+Dean;+Hattendorf,+John+B.;+Estes,+J+W.+(2000).+A+sea+of+words:+a+lexicon+and+companion+for+Patrick+O'Brian's+seafaring+tales|isbn=978-0-8050-6615-9|pages=518|edition=3|url-status=live|archive-url=https://web.archive.org/web/20171111191644/https://books.google.com/books?id=BK-PyCrQ0aMC&printsec=frontcover&dq=King,+Dean;+Hattendorf,+John+B.;+Estes,+J+W.+(2000).+A+sea+of+words:+a+lexicon+and+companion+for+Patrick+O'Brian's+seafaring+tales&hl=en&sa=X&ved=0ahUKEwiP9P_-gqHRAhXHJiYKHfGZDa8Q6AEIGjAA|archive-date=2017-11-11}}</ref> :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; on a mainsail, the sheet is connected to the boom (if present) near the clew.<ref name="SAIL Magazine 101" /> ''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 below rather than to adjust the angle it makes with the wind.<ref name = Hattendorf/> The corner where the leech and the foot connect is called the ''clew''.<ref name="SAIL Magazine 101" /> The corner on a fore-and-aft sail where the luff and foot connect is called the ''tack''<ref name="SAIL Magazine 101" /> and, on a mainsail, is located where the boom and mast connect.<ref name="SAIL Magazine 101" /> :In the case of a symmetrical spinnaker, each of the lower corners of the sail is a clew. However, under sail on a given tack, the corner to which the spinnaker sheet is attached is called the ''clew'', and the corner attached to the spinnaker pole is referred to as the ''tack''.<ref name = Hattendorf/><ref name="SQRG">{{cite web|title=Sailing Quick Reference Guide|url=http://www.wyc.org/portals/0/forms-docs/seminars-tsang.pdf|website=Wayzata Yacht Club|access-date=4 October 2016|url-status=live|archive-url=https://web.archive.org/web/20170105235131/http://www.wyc.org/portals/0/forms-docs/seminars-tsang.pdf|archive-date=5 January 2017}}</ref> On a square sail underway, the tack is the windward clew and also the line holding down that corner.{{sfn|King|Hattendorf|Estes|2000|page=416}} *''Draft'' – Those triangular sails that are attached to both a mast along the luff and a boom along the foot have depth, called ''draft'', which results from the luff and foot being curved, rather than straight as they are attached to those spars. Draft creates a more efficient airfoil shape for the sail. Draft can also be induced in triangular staysails by adjustment of the sheets and the angle from which they reach the sails.<ref name="RYA sail draft">{{cite web|first=Simon|last=Jinks|title=Adjusting Sail Draft|url=http://www.rya.org.uk/knowledge-advice/cruising-tips/boat-handling-sail/Pages/adjusting-sail-draft.aspx|website=Royal Yachting Association|access-date=4 October 2016|url-status=live|archive-url=https://web.archive.org/web/20161005131808/http://www.rya.org.uk/knowledge-advice/cruising-tips/boat-handling-sail/Pages/adjusting-sail-draft.aspx|archive-date=5 October 2016}}</ref>

==Material== thumb|Laminated sail with Kevlar and carbon fibers. {{Main|Sailcloth|Sail components#Materials}} Sail characteristics derive, in part, from the design, construction and the attributes of the fibers, which are woven together to make the sail cloth. There are several key factors in evaluating a fiber for suitability in weaving a sail-cloth: ''initial modulus'', ''breaking strength (tenacity)'', ''creep'', and ''flex strength''. Both the initial cost and its durability of the material define its cost-effectiveness over time.<ref name=Textor/><ref name=Hancock> {{cite book |last1 = Hancock |first1 = Brian |last2 = Knox-Johnson |first2 = Robin |title = Maximum Sail Power: The Complete Guide to Sails, Sail Technology, and Performance |publisher = Nomad Press |date = 2003 |pages = [https://archive.org/details/maximumsailpower00hanc/page/288 288] |url = https://archive.org/details/maximumsailpower00hanc |url-access = registration |quote = sail panel cut. |isbn = 978-1-61930-427-7 }}</ref>

Traditionally, sails were made from flax or cotton canvas,<ref name="Hancock" /> although Scandinavian, Scottish and Icelandic cultures used woolen sails from the 11th into the 19th centuries.<ref name="WoolSailcloth"> {{Citation |title=Wool Sailcloth |url=https://www.vikingeskibsmuseet.dk/en/professions/boatyard/experimental-archaeological-research/maritime-crafts/maritime-technology/wool-sailcloth |access-date=2024-03-15 |publisher=Vikingeskibs Museet}}</ref> Materials used in sails, as of the 21st century, include nylon for spinnakers, where light weight and elastic resistance to shock load are valued and a range of fibers, used for triangular sails, that includes Dacron, aramid fibers including Kevlar, and other liquid crystal polymer fibers including Vectran.<ref name = Hancock/><ref name=Textor/> Woven materials, like Dacron, may specified as either high or low ''tenacity'', as indicated, in part by their denier count (a unit of measure for the linear mass density of fibers).<ref name=Rice> {{Citation |last = Rice |first = Carol |title = A first-time buyers checklist |newspaper = Cruising World |pages = 34–35 |volume = 21 |issn = 0098-3519 |date = January 1995 |url = https://books.google.com/books?id=cbA2Sw1wqGQC&q=dacron+tenacity&pg=RA5-PA35 |archive-url = https://web.archive.org/web/20171111191644/https://books.google.com/books?id=cbA2Sw1wqGQC&pg=RA5-PA35&dq=dacron+tenacity&hl=en&sa=X&ved=0ahUKEwicybeFtsDRAhUDJCYKHfxUASoQ6AEIJjAC#v=onepage&q=dacron%20tenacity&f=false |archive-date = 2017-11-11 |access-date = 2017-01-13 |url-status = live }}</ref>

==Construction==

''Cross-cut'' sails have the panels sewn parallel to one another, often parallel to the foot of the sail, and are the least expensive of the two sail constructions. Triangular cross-cut sail panels are designed to meet the mast and stay at an angle from either the warp or the weft (on the bias) to allow stretching along the luff, but minimize stretching on the luff and foot, where the fibers are aligned with the edges of the sail.<ref name=Colgate> {{cite book |last = Colgate |first = Stephen |title = Fundamentals of Sailing, Cruising, and Racing |publisher = W. W. Norton & Company |date = 1996 |pages = 384 |url = https://books.google.com/books?id=MMP841X5Ke4C&q=sail+corner+construction&pg=PA258 |isbn = 978-0-393-03811-8 |url-status = live |archive-url = https://web.archive.org/web/20171111191644/https://books.google.com/books?id=MMP841X5Ke4C&pg=PA258&dq=sail+corner+construction&hl=en&sa=X&ved=0ahUKEwikpaKolL7RAhXGZCYKHQE5DxoQ6AEILDAD#v=onepage&q=sail%20corner%20construction&f=false |archive-date = 2017-11-11 }}</ref>

''Radial'' sails have panels that "radiate" from corners in order to efficiently transmit stress and are typically of higher performance than cross-cut sails. A ''bi-radial'' sail has panels radiating from two of three corners; a ''tri-radial'' sail has panels radiating from all three corners. Mainsails are more likely to be bi-radial, since there is very little stress at the tack, whereas head sails (spinnakers and jibs) are more likely to be tri-radial, because they are tensioned at their corners.<ref name = Hancock/>

Higher performance sails may be laminated, constructed directly from multiple plies of filaments, fibers, taffetas, and films, instead of woven textiles that are adhered together. ''Molded sails'' are laminated sails formed over a curved mold and adhered together into a shape that does not lie flat.<ref name = Hancock/>

Conventional sail panels are sewn together. Sails are tensile structures, so the role of a seam is to transmit a tensile load from panel to panel. For a sewn textile sail this is done through thread and is limited by the strength of the thread and the strength of the hole in the textile through which it passes. Sail seams are often overlapped between panels and sewn with zig-zag stitches that create many connections per unit of seam length.<ref name = Hancock/><ref name = JonesStylios>{{Citation | last1 = Jones | first1 = I. | last2 = Stylios | first2 = G.K. | title = Joining Textiles: Principles and Applications | publisher = Elsevier | series = Woodhead Publishing Series in Textiles | year = 2013 | pages = 624 | url = https://books.google.com/books?id=mw9IAgAAQBAJ&q=sail+seams&pg=PA457 | access-date = 2017-01-12 | isbn = 978-0-85709-396-7 | archive-date = 2023-11-04 | archive-url = https://web.archive.org/web/20231104070119/https://books.google.com/books?id=mw9IAgAAQBAJ&q=sail+seams&pg=PA457#v=snippet&q=sail%20seams&f=false | url-status = live }}</ref>

Whereas textiles are typically sewn together, other sail materials may be ultrasonically welded, a technique whereby high frequency ultrasonic acoustic vibrations are locally applied to workpieces being held together under pressure to create a solid state weld. It is commonly used for plastics, and especially for joining dissimilar materials.<ref name = JonesStylios/>

Sails feature reinforcements of fabric layers where lines attach at grommets or cringles.<ref name = Knight/> A bolt rope may be sewn onto the edges of a sail to reinforce it, or to fix the sail into a groove in the boom, in the mast, or in the luff foil of a roller-furling jib.<ref name="Kipping1847">{{cite book|first=Robert|last=Kipping|title=The Elements of Sailmaking: Being a Complete Treatise on Cutting-out Sails, According to the Most Approved Methods in the Merchant Service...|url=https://books.google.com/books?id=3n8EAAAAQAAJ&q=bolt-rope|year=1847|publisher=F.W. Norie & Wilson|pages=58–72}}</ref> They may have stiffening features, called battens, that help shape the sail, when full length,<ref name = Berman> {{cite book | last = Berman | first = Phil | title = Catamaran Sailing: From Start to Finish | publisher = W. W. Norton & Company | date = 1999 | pages = [https://archive.org/details/catamaransailing00phil/page/219 219] | url = https://archive.org/details/catamaransailing00phil | url-access = registration | quote = Catamaran batten. | isbn = 978-0-393-31880-7 }}</ref> or just the roach, when present.<ref name=Textor/> They may have a variety of means of reefing them (reducing sail area), including rows of short lines affixed to the sail to wrap up unused sail, as on square and gaff rigs,<ref name=Cunliffe> {{cite book |last = Cunliffe |first = Tom |title = Hand, Reef and Steer |publisher = Sheridan House, Inc. |date = 2004 |pages = 178 |url = https://books.google.com/books?id=05F1Vm--4i4C&q=Reefing+sail&pg=PA91 |isbn = 978-1-57409-203-5 |url-status = live |archive-url = https://web.archive.org/web/20171111191644/https://books.google.com/books?id=05F1Vm--4i4C&pg=PA91&dq=Reefing+sail&hl=en&sa=X&ved=0ahUKEwiWjJ-D1L3RAhUGLSYKHcQdCtcQ6AEIHDAA#v=onepage&q=Reefing%20sail&f=false |archive-date = 2017-11-11 }}</ref> or simply grommets through which a line or a hook may pass, as on Bermuda mainsails.<ref name = Hahne>{{cite book | last = Hahne | first = Peter | title = Sail Trim: Theory and Practice | publisher = Sheridan House, Inc. | date = 2005 | pages = 120 | url = https://books.google.com/books?id=3RglfrqPI5MC&q=Reefing+sail&pg=PA94 | isbn = 978-1-57409-198-4 | access-date = 2020-10-20 | archive-date = 2023-11-04 | archive-url = https://web.archive.org/web/20231104070122/https://books.google.com/books?id=3RglfrqPI5MC&q=Reefing+sail&pg=PA94#v=snippet&q=Reefing%20sail&f=false | url-status = live }}</ref> Fore-and-aft sails may have tell-tales—pieces of yarn, thread or tape that are affixed to sails—to help visualize airflow over their surfaces.<ref name = Textor/> {{center| ;Comparison of jib panel construction }} <gallery mode="packed" heights="240px"> Zagiel horyzont.svg|Cross-cut Zagiel birad.svg|Bi-radial Zagiel gwiazda.svg|Tri-radial </gallery>

==Running rigging== thumb|Running rigging on a sailing yacht: {{olist |Main sheet |Jib sheet |Boom vang |Downhaul |Jib halyard }} thumb|Square sail edges and corners (top). Running rigging (bottom). {{Main|Running rigging}} The lines that attach to and control sails are part of the running rigging and differ between square and fore-and-aft rigs. Some rigs shift from one side of the mast to the other, e.g. the dipping lug sail and the lateen. The lines can be categorized as those that support the sail, those that shape it, and those that control its angle to the wind.

===Fore-and-aft rigged vessels=== Fore-and-aft rigged vessels have rigging that supports, shapes, and adjusts the sails to optimize their performance in the wind, which include the following lines: *''Supporting'' – ''Halyards'' raise sails and control luff tension. ''Topping lifts'' hold booms and yards aloft.<ref name=HowardDoane/> On a gaff sail, ''brails'' run from the leech to the spar to facilitate furling.<ref name = Biddlecombe/> *''Shaping'' – ''Barber haulers'' adjust a spinnaker/jib sheeting angle inboard at right angles to the sheet with a ring or clip on the sheet attached to cordage which is secured and adjusted via fairlead and cam cleat.<ref name = Schweer>{{cite book | last = Schweer | first = Peter | title = How to Trim Sails | publisher = Sheridan House, Inc | series = Sailmate | date = 2006 | pages = 105 | url = https://books.google.com/books?id=UMqngdGSpdgC&q=barber+hauler&pg=PA42 | isbn = 978-1-57409-220-2 | access-date = 2020-10-20 | archive-date = 2023-11-04 | archive-url = https://web.archive.org/web/20231104070124/https://books.google.com/books?id=UMqngdGSpdgC&q=barber+hauler&pg=PA42#v=snippet&q=barber%20hauler&f=false | url-status = live }}</ref> ''Kicking straps/boom vangs'' control a boom-footed sail's leech tension by exerting downward force mid-boom.<ref name=HowardDoane>{{cite book | last1 = Howard | first1 = Jim | last2 = Doane | first2 = Charles J. | title = Handbook of Offshore Cruising: The Dream and Reality of Modern Ocean Cruising | publisher = Sheridan House, Inc. | date = 2000 | pages = 468 | url = https://books.google.com/books?id=NB4uFQuUlnEC&q=running+rigging&pg=PA63 | isbn = 978-1-57409-093-2 | access-date = 2020-10-20 | archive-date = 2023-11-04 | archive-url = https://web.archive.org/web/20231104070209/https://books.google.com/books?id=NB4uFQuUlnEC&q=running+rigging&pg=PA63#v=snippet&q=running%20rigging&f=false | url-status = live }}</ref> ''Cunninghams'' tighten the luff of a boom-footed sail by pulling downward on a cringle in the luff of a mainsail above the tack.<ref name = HomeEvans>{{cite book | last1 = Holmes | first1 = Rupert | last2 = Evans | first2 = Jeremy | title = The Dinghy Bible: The Complete Guide for Novices and Experts | publisher = A&C Black | date = 2014 | pages = 192 | url = https://books.google.com/books?id=Dc6EAAAAQBAJ&q=trapeze+wire+dinghy&pg=PT61 | isbn = 978-1-4081-8800-2 | access-date = 2020-10-20 | archive-date = 2023-11-04 | archive-url = https://web.archive.org/web/20231104070125/https://books.google.com/books?id=Dc6EAAAAQBAJ&q=trapeze+wire+dinghy&pg=PT61#v=snippet&q=trapeze%20wire%20dinghy&f=false | url-status = live }}</ref> ''Downhauls'' lower a sail or a yard and can adjust the tension on the luff of a sail.<ref name=HowardDoane/> ''Outhauls'' control the foot tension of a boom-footed sail.<ref name=HowardDoane/> *''Adjusting angle to the wind'' – ''Sheets'' control angle of attack with respect to the apparent wind, the amount of leech "twist" near the head of the sail, and the foot tension of loose-footed sails.<ref name=HowardDoane/> A ''preventer'' attaches to the end of the boom from a point near the mast to prevent an accidental gybe.<ref name=HowardDoane/> ''Guys'' control spinnaker pole angle with respect to the apparent wind.

===Square-rigged vessels=== Square-rigged vessels require more controlling lines than fore-and-aft rigged ones, including the following.

*''Supporting'' – ''Halyards'' raise and lower the yards.<ref name=HowardDoane/> ''Brails'' run from the leech to the spar to facilitate furling.<ref name = Biddlecombe > {{cite book | last = Biddlecombe | first = George | title = The Art of Rigging: Containing an Explanation of Terms and Phrases and the Progressive Method of Rigging Expressly Adapted for Sailing Ships | publisher = Courier Corporation | series = Dover Maritime Series | date = 1990 | pages = [https://archive.org/details/artrigging00steegoog/page/n173 155] | url = https://archive.org/details/artrigging00steegoog | quote = The Art of Rigging: Containing an Explanation of Terms and Phrases and the ... By George Biddlecombe. | isbn = 978-0-486-26343-4 }}</ref> ''Buntlines'' serve to raise the foot up for shortening sail or for furling.<ref name = Biddlecombe /> ''Lifts'' adjust the tilt of a yard, to raise or lower the ends off the horizontal.<ref name = Biddlecombe /> ''Leechlines'' run to the leech (outer vertical edges) of a sail and serve to pull the leech both in and up when furling.<ref name = Biddlecombe /> *''Shaping'' – ''Bowlines'' run from the leech forward towards the bow to control the weather leech, keeping it taut and thus preventing it from curling back on itself.<ref name = Biddlecombe /> ''Clewlines'' raise the clews to the yard above.<ref name = Biddlecombe /> *''Adjusting angle to the wind'' – ''Braces'' adjust the fore and aft angle of a yard (i.e. to rotate the yard laterally, fore and aft, around the mast).<ref name = Biddlecombe /> ''Sheets'' attach to the clew to control the sail's angle to the wind.<ref name = Biddlecombe /> ''Tacks'' haul the clew of a square sail forward.<ref name = Biddlecombe />

==Gallery== {{center| '''Sails on high-performance sailing craft.''' }} <gallery mode="packed" heights="175px"> File:Bladerider-8.jpg|International Moth on foils. File:Funboard.jpg|Windsurfer. File:Bladef16-1up.jpg|Formula 16 catamaran. File:DN ice boat--Ice Nine--Lake Sunapee NH.jpg|DN class ice boat. File:LandYacht.jpg|Land sailing craft. </gallery> {{center| Sails on craft subject to low forward resistance and high lateral resistance typically have full-length battens.<ref name="Berman" /> }}

==See also== ;Components *Sail components *Marine canvas *List of sail emblems *Baggywrinkle ;Concepts *Sailing *Sail twist ;Related *Cruising (maritime) *SkySails ;Types of sails *Mainsail *Mast (sailing) *Wingsail

==Legend== {{Reflist|group=Legend|2}}

==Notes== {{notelist}}

== References == {{Reflist}}

==Further reading==

* {{Cite book|title=Chapman Piloting & Seamanship|date=2006|publisher=Hearst Books|others=Maloney, Elbert S., Chapman, Charles F. (Charles Frederic), 1881-1976.|isbn=1-58816-232-X|edition=65th|location=New York|oclc=71291743}} * {{cite book|last1=Crothers|first1=William L.|title=The Masting of American Merchant Sail in the 1850s An Illustrated Study.|date=2014|publisher=McFarland Publishing|location=Jefferson, North Carolina|isbn=978-0-7864-9399-9}} * {{cite book|last1=Driscoll|first1=John|title=Learn to Sail in a Week-end.|date=April 1991|edition=First|publisher=Knopf (Dorling Kindersley Limited)|location=New-York (London)|isbn=978-0394587455}}, 96-page educational manual in cooperation with the Royal Yachting Association, including many photographs of Peter Chadwik. Other paperback edition, 11. Aug. 1998, ISBN 978-0375703218. *{{Cite book|last=Hancock, Brian.|url=http://www.brianhancock.org/assets/maximum_sail_power.pdf|title=Maximum Sail Power : the Complete Guide to Sails, Sail Technology, and Performance.|date=2003|publisher=Nomad Press|isbn=978-1-61930-427-7|location=New York|oclc=913696173|access-date=2020-05-09|archive-date=2022-04-16|archive-url=https://web.archive.org/web/20220416215301/http://www.brianhancock.org/assets/maximum_sail_power.pdf|url-status=usurped}} * {{Cite book|title=The Sailor's Handbook : The Essential Sailing Manual|date=2006|publisher=International Marine|others=Herreshoff, Halsey C.|isbn=978-0-07-148092-5|location=[Place of publication not identified]|oclc=76941837}} * {{Cite book|last=Jobson, Gary.|title=Sailing Fundamentals : The Official Learn-to-Sail Manual of the American Sailing Association and the United States Coast Guard Auxiliary|others=Betz, Marti., American Sailing Association., United States. Coast Guard Auxiliary.|date=8 September 2008|isbn=978-1-4391-3678-2|edition=Revised and updatedition|location=New York|oclc=892057802}} * {{Cite book|last=Marchaj, C. A. (Czesaw Antony), 1918-|title=Sail Performance: Techniques to Maximise Sail Power|date=2003|publisher=Adlard Coles Nautical|isbn=0-7136-6407-X|edition=Rev.|location=London|oclc=50841634}} * {{Cite book|last=Marino, Emiliano.|title=The Sailmaker's Apprentice : A Guide for the Self-Reliant Sailor|date=2001|publisher=International Marine|isbn=0-07-137642-9|location=Camden, Me.|oclc=48258636}} * {{Cite book|last=Rousmaniere, John|title=The Annapolis Book of Seamanship|others=Smith, Mark (Mark E.)|date=7 January 2014|isbn=978-1-4516-5019-8|edition=Fourth|location=New York|oclc=862092350}} *{{Cite book|last=Seidman, David.|title=The Complete Sailor : Learning the Art of Sailing|date=2011|publisher=International Marine/McGraw-Hill|isbn=978-0-07-174957-2|edition=2nd|location=Camden, Me.|oclc=704984188}}

==External links== {{Commons category|Sails|lcfirst=yes}} {{wiktionary}} *[http://www.sailingtheweb.com/ Sailboats database: sailing yacht specifications worldwide] *[http://www.bsgdev.com Sail Design Software] *[http://www.wb-sails.fi/news/98_11_PerfectShape/Main.htm The quest for the perfect sailshape] {{Webarchive|url=https://web.archive.org/web/20120302233548/http://www.wb-sails.fi/news/98_11_PerfectShape/Main.htm |date=2012-03-02 }} *[https://web.archive.org/web/20081110094154/http://www.cerealog.fr/extra/uk/produits/fabric_sail_design/index.htm FABRIC Sail Design Software] *{{usurped|1=[https://web.archive.org/web/20120314070300/http://www.doylestratis.com/Technology.html Laminated Sails: Doyle Stratis]}} *{{Cite NSRW|short=x|wstitle=Sail}}

{{Sail types}}  {{Sailing manoeuvres|state=collapsed}}

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