Editing Sail components (section)

====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"/>