The BD56 is an innovative hybrid vessel providing the advantages of a motor yacht – with peak speed at 21 knots and those of a sail boat with an excellent sail plan reaching a cruising speed of 9 knots and an even higher downwind speed. With technical specs comparable only with Volvo Ocean Race boats, the BD56 offers carefully designed water line, ideal for gliding, the hull is made of vinylester resin by vacuum infusion, combined with a keel of 3.5m that can be retracted to 2.1m, a carbon mast and the twin helm allow the boat to glide with ease, independently of the power it receives, be it by engine or sail.
Cape Horn Engineering was approached by the Barcelona Yacht Design Group to collaborate in the design of the BD-56. As experts in Computational Fluid Dynamics (CFD), our specialist team applied some of the lessons learnt during the design of 3 consecutive wins of the Volvo Ocean Race to make a positive contribution to the design of the innovative yacht concept.
The same type of well validated CFD simulations as for racing yachts (i.e. America’s Cup, VOR-70 and IMOCA-60) were run for the BD-56 to understand the differences between a pure racing yacht and this concept design. The BD-56 has got a somewhat larger displacement than what is conventional for its length, but has the capability to achieve very high speeds under motor, while at the same time having a more than acceptable sailing performance by using modern construction materials and design features like a planing hull with chines, twin rudders, T-keel, etc.
Wave height and 6 YAW: Sailing 9 knots
The powerful transom mounted engines with their weight aft proved to be challenging. The hull volume distribution, the position of the keel and the ballast bulb had to be looked at carefully to compensate for the weight aft, and consequently the position of the sail plan, in order to obtain a well-balanced yacht under sail. The simulations were essential to come up with the right size of keel and rudder areas and the position and size of the sail plan.
Wave height and pressure coefficient: Motoring 12 knots
Wave height and pressure coefficient: Motoring 18 knots
All in all the design of the BD-56 has been a very interesting hydrodynamic challenge for Cape Horn Engineering and we are very proud of our contribution to this novel design concept.
More information about this innovative yacht concept can be found at: http://www.bdyachts.com/partners/