reefing

Image:Bavaria 36 Kroatien 2006.jpg jib completely furled around the forestay, and mainsail partially furled within the mast (forming a reef) on a Bavaria 36 sloop]]

Sails may have built-in alternative attachment points that allow their area to be reduced. In a mainsail, reefing cringles may be installed in the sail; a cruising boat will typically have two to three pairs. These are pulled down to the boom to form a new tack and clew, reducing the sail's area. The first pair closest to the boom is called a single reef, the next pair is called a double reef, and so on. A sail usually has eyelets at the same level as the reefing cringles. These are used with reefing points (short lengths of small rope either permanently or temporarily fed through the sail) to secure the excess fabric of the sail after reefing; the points are passed under the foot of the sail or round the boom and tied with a reef knot . Alternatively, a reefing line can be fed through all the eyelets and round the foot of the sail. This keeps the wind out of the unused part of the sails and may improve visibility.{{cite book | title=Sailing Fundamentals | publisher=Simon & Schuster | author=Jobson, Gary | year=1998 | isbn=0684849941 | url-access=registration | url=https://archive.org/details/isbn_9780743273084 }}{{cite web |title=How to reef - expert advice from PBO Sail Clinic |url=https://www.pbo.co.uk/seamanship/pbo-sail-clinic-how-to-reef-25713#:~:text=Reefing%20the%20mainsail,right%20place%20and%20properly%20tensioned. |website=Practical Boat Owner |access-date=19 February 2025 |date=26 December 2015}}

Slab or jiffy reefing allows for the quick establishment of a new tack and clew, while the halyard is partially lowered and then raised. One or two reefing lines passing through the sail's luff and leach reef cringles create a new tack and clew for the sail by pulling them tight to the boom. These can be led back to the cockpit to allow crew members to reef without going on deck in heavy weather. Intermediate reef cringles need not be used.{{Cite book |last=Caswell |first=Chris |url=https://books.google.com/books?id=GEMz61vsAv4C&dq=jiffy+slab+reefing&pg=PA90 |title=Chartering a Boat: Sail and Power |date=2001 |publisher=Sheridan House, Inc. |isbn=978-1-57409-111-3 |pages=90 |language=en}}

Roller reefing rolls or wraps the sail around a wire, foil, or spar to reduce its exposure to the wind. In mainsail furling systems the sail is either wrapped around the boom by a mechanism in the gooseneck or hardware inside the boom winds it around a rotating foil. Furling systems controlled with lines led to the cockpit allow reefing without crew having to go on deck in heavy weather. Roller reefing also allows more variable sail area than conventional or jiffy reefing. Countering these advantages are the furled sail possibly not having an optimal shape and sail repair or replacement being more difficult. In-mast roller-furling mainsails are not conducive to good sail shape.{{Cite book |last1=Howard |first1=James D. |url=https://books.google.com/books?id=NB4uFQuUlnEC&dq=jiffy+slab+reefing&pg=PA170 |title=Handbook of Offshore Cruising: The Dream and Reality of Modern Ocean Cruising |last2=Howard |first2=Jim |last3=Doane |first3=Charles J. |date=2000 |publisher=Sheridan House, Inc. |isbn=978-1-57409-093-2 |pages=170 |language=en}}

File:Chesapeake.jpg, showing reef bands across the sails.]]

Square-rigged sails hang from a spar, called a yard. When reefed, the sail is pulled upwards and affixed to the yard at one of the reef bands that runs horizontally across the sail. Each reef band is a canvas-reinforced strip, which contains cringles—eyes through which the reefing points (short pieces of rope) pass that attach the sail to the yard. A sail may have several reef bands to shorten sail to different degrees.{{Cite book |last=Mayne |first=Richard |url=https://books.google.com/books?id=BGYPEAAAQBAJ&dq=reefing+square+rigger&pg=PA233 |title=The Language of Sailing |date=2018-10-24 |publisher=Routledge |isbn=978-1-135-96558-7 |pages=233 |language=en}}

File:Dublin (seal, 1297).pngThe earliest known depiction of reef points is on the Dublin City Seal of 1297.{{cite journal |last1=Brindley |first1=H. H. |title=Mediæval Ships: No. VII |journal=The Mariner's Mirror |date=1 January 1913 |volume=3 |issue=1 |pages=14–17 |doi=10.1080/00253359.1913.10654659 |url=https://doi.org/10.1080/00253359.1913.10654659 |access-date=3 June 2025}} The earliest surviving example of reef points is on the sail for a ship's boat found on the wreck of Vasa, which sank in 1628.{{cite book |last1=Bartoš |first1=Louis|last2=Bengtsson |first2=Sven |last3=Svensson|first3=Sam|last4=Hocker|first4=Fred|editor1-last=Hocker |editor1-first=Fred |title=Vasa. II Part 1: Rigging and sailing a Swedish warship of 1628 The material remains and archaeological context |date=2023 |publisher=Vasamuseet ; Nordic Academic Press |location=Stockholm : Lund |isbn=978-91-88909-11-4 |chapter=7: Sails}}{{rp|326}} Vasa{{'}}s own sails included ones which had {{nautical term|bonnet}}s. These are extra pieces that fasten to the bottom of a sail to increase its area. These were attached for lighter winds and removed in higher winds. This was the common method of adjusting sail area to match wind strength during the Medieval period. Other evidence of use of bonnets has been found on the Mary Rose.{{r|Bartoš 2023}}

• Brail
• Glossary of nautical terms (M-Z)

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{{cite book | title = The Annapolis Book of Seamanship | first = John | last = Rousemaniere | date = 7 January 2014 | isbn = 978-1451650198 }}

{{Sailing manoeuvres}}

Category:Sailing manoeuvres