C&C 30 One-Design Overview
To rank the candidate hulls we developed a parametric race model to evaluate the design outputs from the VPP (Velocity Prediction Program) with reference to a range of wind speeds and angles. It generates a set of weights which are used as multipliers of the raw VPP numbers for VMG (Velocity Made Good) beating, 80 degree reaching, 120 degree reaching, and VMG running between 6 and 20 knots. The final hybrid hull shape exhibits a narrow beam waterline when upright for low drag, but gains form stability quickly as the wider hull shape above the waterline begins to immerse with increasing heel angle, using more of the sail plan’s power and allowing the crew to shift aft to further increase stability. The VPP also outputs data for rudder angles, heel angles, and leeway allowing foil size and location to be fine-tuned, and targets developed for initial sailing trials to speed up the learning process.
In addition to form stability we have maintained a focus on a low VCG (Vertical Center of Gravity). In particular in the context of a Production One Design where most components weights have remained similar over recent generations, the all-carbon keel fin offers a major reduction in weight. The custom rudder and keel sections were developed to optimize performance and handling with non-critical stall properties at large angles of attack. The bulb similarly has been shaped to promote laminar flow and maximize bulb VCG.
Designer Notes From Mark Mills
The C&C 30 One Design project was a great opportunity to put our design team methodology to work, getting the best from experts in each of the different but connected specializations in a front line high performance yacht design.
The C&C 30 represents a balanced approach to a high performance One Design, which needs to perform in many locations around the world, across the full range of wind speeds and on a wider range of course types, from traditional windward/leewards to offshore courses and everything in between. Using the DasBoot CFD Panel code (Computational Fluid Dynamics) we ran a series of hull shapes to evaluate the various trade-offs available to optimise the design. Various iterations were investigated including variations of stern and bow shapes, beam and rocker distribution, and chine heights to identify a hull shape that could perform well across the wind range. As progress was made the improved shapes became the basis of the next iteration to combine the positive attributes.
The 2 spreader rig design was developed with Hall Spars to minimize rig weight without losing tube stiffness or increasing windage, and maintaining a focus on simplicity and repeat-ability of rig tune. The sail plan size and aspect ratios were investigated in CFD to ensure that the most powerful solution compatible with the full range of sailing conditions, balancing the righting moment and heeling moments to position the complete design solution in the middle of the spectrum.
