On wings and keels

Article type: Research Article

Authors: Slooff, J.W.

Affiliations: Theoretical Aerodynamics Dept., National Aerospace Laboratory NLR, Amsterdam, The Netherlands

Abstract: A discussion is given of the physical mechanisms governing the hydrodynamics of sailing yacht keels and the parameters that, through these mechanisms, determine keel performance. It is concluded that due to the presence of the free water surface optimum keel shapes differ from optimum shapes for aircraft wings, a fact that does not seem to have been widely recognized. Utilizing computational fluid dynamic analysis and optimization methods it is found that the performance of conventional keels can be improved significantly by reducing taper or even applying inverse taper (‘upside down’ keel) and that dramatic improvements in performance can be realized through keels with ‘winglets’ as utilized by the 1983 America’s Cup winner ‘Australia II’.

DOI: 10.3233/ISP-1984-3135603

Journal: International Shipbuilding Progress, vol. 31, no. 356, pp. 94-102, 1984