Cookson 50 Transpac 52

Designer’s Notes

• Beam optimization studies for the proposed venues/conditions Weather studies initially focused on Mediterranean venues, and then were expanded to include US venues to explore if and how the designs should be adjusted to suit these areas. Design #585 was developed to meet the demands of a specific selection of Mediterranean venues; design #586 was developed to fit a broader mix of regatta conditions. This generation of designs has slightly narrower waterline beam and slightly wider maximum beam than our previous designs. Within the "box" the Transpac 52 rule has few limits and allows the designer to apply their skills to developing the sweetest possible hull shape. Observations of our existing boats at various speeds and loading combined with the results of heeled and upright CFD studies have led us to make these new hulls more dinghy-like with straighter ends to maximize effective length at high speeds. Bow entry shapes were developed recognizing the need for upwind performance in sometimes bumpy conditions while at the same time using the full length available in the "box". For optimum performance in the wide range of conditions prevalent in the Mediterranean these new designs have minimized wetted surface and moderate beam for light winds yet transform into powerful, maximum length forms at high speed. Overall the shape will be slippery downwind and provide stability and good performance in upwind chop. Appendage research and design applied the latest tools available to create better fin, bulb and rudder geometries. Great care was taken to position these relative to the rig to provide workable balance over a wide range of sail configurations and wind strengths. Bulb shapes have benefited from our previous wind tunnel, CFD and tank work for Volvo Round the World Race projects plus some new studies to make the fin and bulb complement each other for better lift/drag production. Deck layout and cabin geometry have been designed to give working space for critical racing maneuvers and sail changes and provide deck areas for efficient sheeting. A twin pedestal arrangement provides the necessary crew horsepower input for gybing and other racing maneuvers. Aft topsides at the transom have been whittled away to save weight and move the aft boundary of the working deck further forward. The wheels are set well outboard to give the helmsman the most effective driving position. The interior arrangement has been simplified to its racing functionality. Structural detailing has been reviewed to reduce weight and maintain reliability. The resulting weight savings have been used to congregate weight centrally in the boat to reduce pitching inertia and allow some exchange of volumes between appendages and hull. Rigs are fairly standard 20 degree swept spreader layout with a freestanding topmast without the "cathedral" style stay support system. The stay envelope has been carefully set out to achieve the most efficient sheeting of the overlapping code zero upwind sail. The mast has been designed to class rule minimum weight and VCG height.