This study deals with the estimation of the compressive strength of carbon fibre reinforced plastics composites used in yacht racing. This property is one the key design parameters in marine engineering. The mechanism of fibre micro-buckling as well as a structural effect including the neighbouring plies of the unidirectional ply and the deformation gradient linked to the the mechanical loading are taken into account to propose an analytical model for estimating this property. The parameters involved require a number of experiments to characterise the microstructure at the level of components (fibre, matrix, ply) and the mechanical behaviour (elastoplasticity). Some of them can be estimated using a micro-mechanical approach. It is shown that estimations and experiments show good agreement on two cases: one with a constant deformation gradient, the other one in pure compression. The paramount influence of the initial misalignment of the fibre is highlighted.

An implementation of a kite modelling approach into 6 degrees of freedom sailboat dynamic simulator is introduced. This enables an evaluation of kite performance in comparison with classical rig sailing. A “zero-mass” model was used to model kite forces. Influence of the wind gradient was properly taken into account which led to significant modifications in the calculation of the relative wind, both in magnitude and in orientation. The modelling is performed with real aerodynamic characteristics given by experimental data. An optimization is done to determine the best kite flight configuration in terms of performance. Validation steps of the sail yacht simulator are performed for a classical rig on the example of an 8 meter one design yacht. The experimental setup is described and validation results are discussed. An interpolation technique in space and time of the wind mesh was used, based on measurements made at four different locations of the navigation spot. Boat motions were recorded by high resolution GPS and inertial unit systems. Speed polar diagram results, reached by kite propulsion, were predicted versus true wind angle. At last a comparison is made for upwind and downwind legs in sea trials conditions, between simulations with the classical rig and the kite. It is shown that the boat towed by kite would achieve much better sailing performance.