Editing Sail components (section)

==Shape==
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[[File:Square rigged sail parts and running rigging.jpg|thumb|Square sail edges and corners (top), [[running rigging]] (bottom)]]
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'', the trailing edge is the ''leech'', and the bottom edge is the ''foot''.

*''Head'' {{anchor|Head}}– The ''head'' is the upper edge of the sail, and is attached at the throat and peak to a gaff, [[yard (sailing)|yard]], or sprit.{{sfn|King|Hattendorf|Estes|2000|page=283}} For a triangular sail the ''head'' refers to the topmost corner.
*''Leech''{{anchor|Leech}} – The aft (back) edge of a fore-and-aft sail is called the ''leech'' (also spelled ''leach'').<ref name="SAIL Magazine 101" /> The ''leech'' is either  side edge of a symmetrical  sail—triangular or square.{{sfn|King|Hattendorf|Estes|2000|page=283}}{{sfn|King|Hattendorf|Estes|2000|page=271}}{{efn|name=oxford|The traditional terminology is for the two leaches of a square sail to be referred to as the "weather" and "lee", depending on the bracing of the yards, or "port" and "starboard".<ref>''The Oxford Companion to Ships and the Sea," Peter Kemp, p. 739</ref>}} However, once a symmetrical sail has wind blowing along its surface, whether on a [[Point of sail#Reaching|reach]] or [[Point of sail#Close-hauled|close-hauled]], the windward leech may be called a ''luff'' (see below).
*''Luff''{{anchor|Luff}} – The forward (leading) edge of a fore-and-aft sail is called the ''luff'', and may be attached along a [[mast (sailing)|mast]] or a [[Stays (nautical)|stay]].<ref name="SAIL Magazine 101" /> When on a reach, the windward leech of a spinnaker (symmetrical or not) is called the luff<ref>{{Cite book |chapter-url=https://books.google.com/books?id=5vMeEL0Pts0C&q=Spinnaker+luff&pg=PA106 |title=The Best of Sail Trim |last=Stanton |first=John R. |date=2000 |publisher=Sheridan House, Inc. |isbn=9781574091199 |editor-last=Mason |editor-first=Charles |location=Davie, Florida |pages=106–7 |language=en |chapter=The spinnaker on a broad reach}}</ref> and, when on a reach or close-hauled, the windward leech of a square sail may be called the luff or the ''weather leech''.{{sfn|King|Hattendorf|Estes|2000|page=283}}{{sfn|King|Hattendorf|Estes|2000|page=271}}{{efn|name=oxford}}
*''Foot''{{anchor|Foot}} – The ''foot'' of a sail is its bottom edge.<ref name="SAIL Magazine 101">{{cite web |title=Know How: Sailing 101 |url=http://www.sailmagazine.com/cruising/cruising-tips/basic-sailing-101/ |work=Sail Magazine |access-date=4 October 2016 |language=en}}</ref> On a fore-and-aft mainsail, the foot is often attached, at the tack and clew, to a [[boom (sailing)|boom]]; on a square sail to a spar by clews on both ends; if no boom or spar is present, the sail is said to be "loose-footed".{{sfn|King|Hattendorf|Estes|2000|page=271}}

====Roach====
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'',{{anchor|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 [[Sail batten|battens]].<ref name=Textor/> 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 (nautical)|chafing]] the sail.<ref name = Nicolson/>

''Roach'' is a term also 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 greater the departure from the straight line, the greater the "hollow" in the roach.<ref>{{cite book|author=David Steele|url=https://www.hnsa.org/manuals-documents/age-of-sail/the-elements-and-practice-of-rigging-and-seamanship/sail-making-vol-i/|title=The Elements and Practice of Rigging And Seamanship|year=1794|volume=1|page=126}}</ref><ref>{{Cite book |last=McKay |first=John |url=https://books.google.com/books?id=bxLmDwAAQBAJ&dq=%22hollow-footed%22+sail&pg=PA92 |title=Sovereign of the Seas, 1637: A Reconstruction of the Most Powerful Warship of its Day |date=2020-02-28 |publisher=Seaforth Publishing |isbn=978-1-5267-6632-8 |pages=91–2 |language=en}}</ref> The roach 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===
[[File:Schema-genois-enrouleur.jpg|thumb|[[Genoa jib]], showing reinforcement and attachment points:<br>
1. Head 2. Reinforcement 3. Luff <br>4. Leech 5. Anti-UV covering <br>6. Headfoil attachment 7. Panel(s) <br>8. Telltales 9. Reinforcement <br>10. Tack 11. Leech control 12. Clew <br>13. Foot control 14. Foot <br>15. Furling marks]]
The names of corners of sails vary, depending on shape and symmetry.

*''Head'' {{anchor|Head (corner)}}– In a triangular sail, the corner where the luff and the leech connect is called the ''head''.{{sfn|Jobson|2008|page=208}}<ref name="SAIL Magazine 101"/> On a square sail, the top corners are ''head cringles'', where there are grommets, called [[cringle]]s.<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}}</ref>

*''Peak '' {{anchor|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'' {{anchor|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.<ref>{{cite book |last1=Underhill |first1=Harold |title=Sailing Ship Rigs and Rigging |date=1938 |publisher=Brown, Son and Ferguson |location=Glasgow |page=114 |edition=Second, 1958 |chapter=Glossary}}</ref> Gaff-rigged sails, and certain similar rigs, employ two ''[[halyard]]s'' to raise the sails: the ''[[throat halyard]]'' raises the forward, throat end of the gaff, while the ''[[peak halyard]]'' raises the aft, peak end.{{sfn|King|Hattendorf|Estes|2000|page=429}}
*''Clew'' {{anchor|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; 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 ''[[sheet (sailing)|sheet]]s'' 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.{{sfn|King|Hattendorf|Estes|2000|page=146}} The corner where the leech and the foot connect is called the ''clew''.<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''. {{sfn|King|Hattendorf|Estes|2000|page=146}}
*''Tack'' {{anchor|Tack}}– The [[Tack (sailing)|tack]] is the corner on a fore-and-aft sail where the luff and foot connect<ref name="SAIL Magazine 101" /> and, on a mainsail, is located where the boom and mast connect.<ref name="SAIL Magazine 101" /><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}}</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===
{{Main|Draft (sail)}}
Those triangular sails that are attached to both a mast along the luff and a boom along the foot have depth, known as ''[[Draft (sail)|draft or draught]]'', 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}}</ref>