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Alfa-Laval Oct 2019


Paper Title: Comparison of Modern Keel Types for Sailing Yachts



K Ljungqvist, SSPA Sweden AB, Sweden
M Orych, FLOWTECH International AB, Sweden
L Larsson Chalmers University of Technology, Sweden
C Finnsgård, SSPA Sweden AB, Sweden


The performance of three bulb keels is compared with that of a traditional fin keel. Hydrodynamic data from wind tunnel tests are used in a velocity prediction program (VPP) with the keels fitted to a 40’ cruising yacht. Two scenarios are investigated: keel retrofitting and new design. In retrofitting, the sail, mast and rig are unchanged, while in new design they are varied to obtain a constant heel angle (Dellenbaugh). Three keel materials are considered: cast iron, lead or a mix thereof. As expected, the bulb keels are superior to the fin keel in all but the lightest winds in the retrofit scenario. The differences between the bulb keels are small, but the keel with a bulb integrated with the fin is slightly slower than the keels with more distinct bulbs, in either L- or T-configuration. These are very close in retrofit, but the T-configuration has a slight advantage in the new design scenario.


Transactions RINA, Vol 159, Part B2, International Journal of Small Craft Technology, Jul-Dec 2017 

DOI Number

DOI No: 10.3940/rina.ijsct.2017.b2.203

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