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La réalisation du simulateur a été motivée par la perspective de son utilisation à des fins sportives. L'objectif est de disposer d'un outil d'analyse tactique et stratégique afin d'apporter des réponses quantifiées aux questions des coureurs. La dernière partie de cet article présente un exemple du type de réponse que peut apporter le simulateur pour l'évaluation de scenarii tactiques. Pour que ces réponses soient pertinentes, il faut que le simulateur soit validé par des essais en navigation accompagnés de la mesure du vent sur le plan d'eau. Ces validations ont commencé et nous exposerons nos premières expériences dans ce domaine. Une première campagne de mesure a eu lieu lors d'une compétition de match racing. Une deuxième campagne a été réalisée sur un seul bateau avec une chaîne de mesures plus complète fournissant une position plus précise, l'attitude du bateau et l'angle de barre. Cette campagne comportait des essais de manœuvrabilité (sans voiles) en vue d'une validation partielle du simulateur et des essais sous voiles pour une validation globale

A dynamic kite flight can affect ship motions. Ship equations of motion associated with the analytical zero-mass kite model are developed. Aiming a realistic amplitude modeling of the kite excitation, a linear modification of the aerodynamic kite specs with the turning rate of the kite velocity heading is proposed. A good agreement with experimental data is obtained. Equations of motion are solved on a reaching path alternatively with a weak and a strong coupling between the ship and the kite. Differences between the two coupling methods become significant when a harmonic of the kite excitation approaches the natural roll frequency of the ship. For the presented case of study, these critical conditions can be avoided with longer tethers or larger kite trajectories.

This paper describes current progress made towards the realization of a match-racing simulator. The aim of the project is to be able to simulate and to modify typical situations while introducing quantifiable data for strategic and tactical analysis. The fundamental model consists of six fully coupled equations of the dynamics of two boats. The largest possible number of variables is taken into account, even though some are initially approximations. The influences of the three attitude angles on the hydrodynamic forces are taken into account using the ‘experiment planning method’ applied to towing-tank tests. For the aerodynamics, empirical models (for example IMS) are adopted. The interaction between the two boats is obtained by representing the sail perturbation by means of a single horseshoe vortex and a self-preserved viscous plane wake. The simulator has a modular structure, which allows the progressive improvement of each part as studies and knowledge advance. Comparisons with calculations of three-dimensional flows and with wind tunnel measurements validate the interaction model. The results presented show a satisfactory agreement with the polar velocity diagram available for the studied boat, even if more reliable trials at sea are needed, with measurements of boat behaviour, wind and sea state. Simulations allow us to quantify the relative influence of model coefficients on boat behaviour. Thus it is possible to identify which factors must be improved first. Tacking simulations are used to illustrate this possibility. To conclude, an example of the practical use of the simulator is presented by comparing two tactical scenarios for the final part of the upwind leg.

SEA Design developed a fluid structure method (FSI) suitable for early design stage of appendage with complex shapes dedicated to the America’s Cup flying catamarans. The aerodynamic loading and the boat weight are counteracted by the appendages and mainly the dagger-board. Consequently, the appendage structural design is very critical. Based on a 3D lifting line and a modified beam element method, the GSEA Design FSI method takes less than one minute to compute. An illustrating example on a L-shape appendage shows that the FSI results compared to a non-FSI results can be particularly different at the elbow. Thanks to the short computational time of the method, multi-objective optimizations can be performed. For instance a second ilstrating example shows the optimization of the appendage weight and stiffness.

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