Practical analysis of the hydrodynamic performance of the Reflex 28 keel and rudder

The performance of the underwater appendages and hull of the Reflex 28 yacht have been analysed using a surface panel code. The objective of the work was to assess the ease with which such a code could be used as part of the design process using computational resources already available to the yacht designer. The flexible geometry creation process allowed the complete hull, keel-bulb and rudder configuration to be defined both for upright and heeled configurations and tested for a range of hull drift and rudder angles. The surface panel solution was obtained using an iterative process whereby each underwater component was solved independently and then in the presence of the velocity field induced by all the other components. This Interaction Velocity Field approach allows high panel density on each component and reduces the numerical difficulties associated with body-wake intersection. The results of the analysis confirmed performance features observed in the actual behaviour of the Reflex 28, allowed greater insight into the mechanisms of flow interaction and allowed the relative side force contributions to be determined. It was concluded that, used with care, surface panel codes can provide the yacht designer with a detailed understanding of underwater appendage performance. The ability to rapidly change the geometric definition offers the possibility of cost-effective design optimisation even on a modest budge