Leggi l’articolo in italiano
We talked about BD56 when we had its first renderings and information last February. It’s a sailing-motor boat, (16.62 metres long) which can reach 21 knots thanks to two 350 HP outboards. It will be produced by BD Yachts and designed by BYDGROUP. The most interesting and innovative technical aspect concerns engines.
The shipbuilder has decided to use outboards because “any inboard propulsion systems available on the market didn’t prove to be efficient for our particular project. High thrust propellers would have been good to obtain high speeds but there isn’t a model with foldable wings to reduce resistance and friction when the boat is used as a sailing boat. So, we studied some retractable propellers but it was an expensive and technically difficult solution which would have created some problems in terms of long-term reliability”.
For this particular yacht, BYDGROUP was looking for an efficient cheap propulsion system which was easy to use, with a good weigth/power ration and able to reduce friction of propeller-holder axis, struts and blades. The result? ” Classical outboards! Thanks to the possibility to have a push with a zero-degree-angle against DWL, the momentum applied by the propeller is the same than the conventional one of an axle line. Moreover, the possibility to change the angle of the pushing line means greater efficiency”.
What are the advantages ? “Outboards are easy to install and maintain, they ensure an easy manoeuvre through their joystick, they can be raised if not used, they have a reduced weight and a good weight/power ratio (about 1hpx1kg). Moreover, you can receive assistance and spare parts anywhere in the world”.
Outboards will be hidden in the transom under the deck, in a ventilated space, big enough to raise them when they are not used. You can use a 200 hp outboard (maximum speed: 11.5 knots) or two 350 hp motors (maximum speed: 21 knots).
In order to study and analyze the performances of the boat, in both modalities “sailing” and “motor”, BD YACHTS and BYDGROUP used a series of computational fluide-dynamic data : they drew over 20 different hull models and configurations and they tested them in a virtual naval pool, where they simulated the real weather-marine conditions. These calculations were made by Cape Horn Engineering (CHE), a specialized and worldwide-known team, which has optimized some projects of Volvo Ocean Race and American Cup ( Ben Ainslie, for example, is a customer of theirs).
But how much will this cost? Given that BD56 is a unique yacht, totally tailored, its price will be different according to the different cases but it will generally have a 5-year-warranty and a complete maintenance service and it will cost about 2.2 million Euros. Delivery times for the first unit are 15 months.