Hanging in there

Performance analysis specialist Claudio Fassardi believes that, given careful application, modern tank testing continues to hold up well against newer rival methodologies

Since its inception in the 1970s the Velocity Prediction Program (VPP) has become the principal tool for the determination of sailboat performance. Using an iterative process, the VPP finds the sailing parameters (velocity, heel and yaw among others) for a range of true wind angles and velocities at which the hydrodynamic and aerodynamic forces and moments acting on the sailboat are statically balanced. Simplified models are used to represent these forces and moments, and it therefore becomes obvious that the closer these models represent the actual physics involved the better the VPP predictions will be.

Despite the significant advances in numerical techniques and computer power that now allow Computational Fluid Dynamics (CFD) to produce good and cost-effective results, tank testing still constitutes a very important tool for the determination of sailboat hydrodynamic models.

To read the remainder of this article please go to the March 2003 edition of Seahorse, available at selected newsstands or by calling: + 44 (0) 1590 671899 or by email at: info@seahorse.co.uk

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Above: Full scale... as Alinghi shows a consistent edge over the best that Oracle and Farr Yacht Design could produce during the Louis Vuitton final. Never before has any design team tested at the level of these two and yet, if anything, Alinghi masked the true size of their advantage throughout the Cup. It is fair to say that of the two Alinghi placed marginally more emphasis on their tank work (in St Johns) compared to computer simulations