An innovative and ambitious boat
Swiss Solar Boat’s design is imagined on the basis of a proa with addition of foils to reduce drag at high speed. For efficiency our design used a combination of three actuated “T” foil.
A technical challenge for the structure
The structure must be as light as possible while withstanding huge loads of more than one ton. This will be achieved using cuting edge technologies in terms of composite materials. Indeed, this is thanks to thin-fold carbon prepregs (Thinpregs) of the order of 0.04mm per fold with ultra high modulus fibers (T800-HR40) (NTPT link). This will allow us to reach wall thicknesses between 0.25-1mm. In addition, the use of sandwich structure based on a nomex honeycomb body or Airex foam will significantly increase the bending stiffness locally with minimal weight increase.
It is necessary to develop the geometry of the different parts on CAD software (Catia) and test them with theoretical load cases modeled by finite elements (Abaqus). After several iterations, it becomes possible to refine the choice of materials used and the dimensions of the different structures.
In addition, the surface condition of structures in contact with water is of enormous importance to reduce drag. This requires a long, complex and expensive implementation based on the creation of negative carbon moulds.
A technical challenge for solar
At any time, the solar modules must deliver a maximum of power to the boat and under any conditions. Thanks to the best monocrystalline silicon solar cells, we harvest as much solar energy as we can. Lightness is key! therefore homemade modules were developed weighting under a kilo per meter square. The dimensions and layout of the modules were optimized taking into account the shape of the deck, potential shadowing and electrical constrains.
A second challenge lies in the mounting od the modules on the deck. In fact, the stiffness of the deck guarantees the integrity of the modules, however, they should hold through any sailing conditions. A gluing system, simple although robust, provides sufficient anchoring as well as lightness.
A third challenge lies in the modules and boat load interface, especially the battery. The goal is to extract maximum power without loss, that is achieved thanks to the MPPT (Maximum Power Point Trackers). An MPPT is in a sense an electric converter, which knows the power it should deliver at any time. That is crucial is the pilot requests full power on very short notice.