The interaction of downwind sails

William C. Lasher

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

When a sailboat is sailing in the general direction of the wind, it is known as downwind sailing. Under these conditions boats generally carry two sails - a mainsail and a spinnaker. The flow over these sails is complicated and poorly understood. An issue of importance to sailors is how the adjustment of one sail affects the aerodynamics of the other sail and the total driving force. In the present work a CFD analysis was performed on two different sailboat rigs, with an emphasis on the interactions between the main and spinnaker. The results show that the optimum angle of attack of the mainsail is generally 60° to 70°, depending on the direction of the wind relative to the boat. The correct setting for a mainsail has been a point of debate amongst sailors, and the present analysis supports the theory of easing the mainsail until it luffs (or flaps), then pulling it in. A surprising result is that when the wind is directly behind the boat, the mainsail should not be set to maximize projected area, but eased out past 90°. This is difficult to accomplish in practice due to restrictions of the rig, but raise some interesting questions.

Original languageEnglish (US)
Title of host publication2006 ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006
Volume2006
StatePublished - 2006
Event2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006 - Miami, FL, United States
Duration: Jul 17 2006Jul 20 2006

Other

Other2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006
CountryUnited States
CityMiami, FL
Period7/17/067/20/06

Fingerprint

Boats
Sailing vessels
Angle of attack
Aerodynamics
Computational fluid dynamics

All Science Journal Classification (ASJC) codes

  • Engineering(all)

Cite this

Lasher, W. C. (2006). The interaction of downwind sails. In 2006 ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006 (Vol. 2006)
Lasher, William C. / The interaction of downwind sails. 2006 ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006. Vol. 2006 2006.
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Lasher, WC 2006, The interaction of downwind sails. in 2006 ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006. vol. 2006, 2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006, Miami, FL, United States, 7/17/06.

The interaction of downwind sails. / Lasher, William C.

2006 ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006. Vol. 2006 2006.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Lasher WC. The interaction of downwind sails. In 2006 ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006. Vol. 2006. 2006