Parametric models are good candidates for modeling the dynamic behavior of racing sailboats. A large number of different models have already been developed for boats. Each one has its specificity, and works with its own set of inputs/outputs. This paper presents the Advanced Vessel Simulation environment, a framework which allows the rapid programming of sailboat simulators by creating assembly of pre-existent and custom software components. The environment describes those different components, and generates the “glue” code allowing the communication between them during the simulation process. The goal of the AVS environment is to compare the accuracy and the performances of several parametric models. Different numerical criteria are implemented. They allow the comparison of several parametric models in given sailing points and weather conditions. The AVS environment is used to compare three parametric models of a racing foiling multihull, which have different levels of specific knowledge in their equations. It turns out that accuracy of models depends on the considered output data. AVS framework provides tools to find the best model to each output, and then to build a mixed model, adapted to the simulation needs.

While sailing offwind, the trimmer typically adjusts the downwind sail "on the verge of luffing", letting occasionally the luff of the sail flapping. Due to the unsteadiness of the spinnaker itself, maintaining the luff on the verge of luffing needs continual adjustments. The propulsive force generated by the offwind sail depends on this trimming and is highly fluctuating. During a flapping sequence, the aerodynamic load can fluctuate by 50% of the average load. On a J/80 class yacht, we simultaneously measured timeresolved pressures on the spinnaker, aerodynamic loads, boat and wind data. Significant spatio-temporal patterns are detected in the pressure distribution. In this paper we present averages and main fluctuations of pressure distributions and of load coefficients for different apparent wind angles as well as a refined analysis of pressure fluctuations, using the Proper Orthogonal Decomposition (POD) method. POD shows that pressure fluctuations due to luffing of the spinnaker can be well represented by only one proper mode related to a unique spatial pressure pattern and a dynamic behavior evolving with the Apparent Wind Angles. The time evolution of this proper mode is highly correlated with load fluctuations. Moreover, POD can be employed to filter the measured pressures more efficiently than basic filters. The reconstruction using the first few modes allows to restrict to the most energetic part of the signal and remove insignificant variations and noises. This might be helpful for comparison with other measurements and numerical simulations.

Hydrofoil supported sailing vessels gained more and more importance within the last years. Due to new processes of manufacturing it is possible to build slender section foils with low drag coefficients and heave stable hydrofoil geometries are becoming possible to construct. These surface piercing foils often tend to ventilate and undergo cavitation at high speeds. The aim of this work is to define a setup to calculate the hydrodynamic forces on such foils with a RANS based CFD method and to investigate whether the onset of ventilation and cavitation can be predicted with sufficient accuracy...