More trial less error

The evaluation of canting-keel dynamics is coming of age; America's Cup consultant Claudio Fassardi has been working with Karsten Hochkirch of Friendship Systems in Germany to advance the science…

In upwind sailing conditions the canting-keel concept improves the performance of a sailboat by adding stability. At the same time, however, the flow pressures induced by the presence of the bulb in close proximity to the water surface generate an undesirable resistance manifested by the formation of waves. However, canting-keel sailboats have proved beyond doubt that the relatively large performance gains achieved due to greater stability significantly offset the negative effect of the additional wave-making resistance produced by the bulb.

My colleague Karsten Hochkirch and I set ourselves the task of minimising the total or 'global' resistance of a canting-keel sailboat design; just as the bulbous bows common on large ships work successfully, we felt that a given yacht hull shape should have a 'matching' bulb that, within a range of upwind sailing conditions, should be able to interfere in a positive — rather than negative — manner with the wave system generated by the hull and so achieve minimum total wave-making resistance.

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