Following the January 2016 presentation of the BD56 project, Tià Simó, Naval Architect and Managing Partner at BYDGROUP – naval architect and designers of BD56 – provides us with more details and further clarifications based on the questions received over these last few months.
BD56 engines
The BD56 has very specific needs in terms of propulsion that conventional sailing yachts and conventional motor yachts have not. While developing the project, the BYDGROUP team found that the inboard propulsion systems available were inefficient for the BD56’s particular design. For a high-speed design, high thrust propellers are required, but they are unavailable in a folding version, necessary to reduce drag when sailing. Retractable propellers were another possible solution, but they are technically complicated and have reliability issues, as well as being very costly due to necessary customization.
With the BD56, BYD GROUP needed the most efficient and convenient propulsion system available on the market, requiring reliability, ease of use and maintenance, sufficient power to weight ratio, and very importantly, a way to reduce drag from submersed appendages: shafts, struts, and propellers. The result was unexpected – outboard engines!
With thrust at a 0º angle to the DWL with an outboard engine, the drive applied by the propeller is equivalent to the drive applied by a conventional shaft at a 10º angle. In addition, the possibility of changing the thrust line angle provides for even greater efficiency.
Given the low weight of the outboards, the position of the CoG in balancing the hull with drive applied from the stern is equivalent to that of a conventional inboard configuration. The engines are hidden in the transom of the boat below the deck, well ventilated and with sufficient space to be lifted out of the water when sailing.
The power available for the BD56 is either one 200 hp engine (11,5 Knots Max) or two 350 hp engines (21 Knots Max).
CFD test
The naval architects Tià Simó and Raul Gonzalo designed more than 20 different hull models and configurations that were tested in a virtual Towing Tank, where real conditions were simulated. For the calculations BYDGROUP worked with a specialized team with Volvo Ocean Race and America’s Cup experience, Cape Horn Engineering: the accuracy of the results is within 5% of the theoretical design data. Their experience in the optimization and analysis of planing sailing yachts is a warranty for success. With the help of CHE, BYDGROUP developed an optimal design giving the best performance both under sail and under power.
BD56 prices and delivery
The BD56 is a tailor made product, built considering the needs of their future owners in multiple configurations, colors and finish qualities, to meet the demands of the most demanding yachtsman, and therefore yard does not have an exact price. A full option BD 56 with a five (5) year warranty & maintenance service has an estimated price of 2.2 million euros. Delivery time for the first unit is 15 months.
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