The paper presents an overview of a joint project developed among Politecnico di Milano, CSEM and North Sails, aiming at developing a new sail pressure measurement system based on MEMS sensors (an excellent compromise between size, performance, costs and operational conditions) and pressure strips and pads technology. These devices were designed and produced to give differential measurement between the leeward and windward side of the sails. The project has been developed within the Lecco Innovation Hub Sailing Yacht Lab, a 10 m length sailing dynamometer which intend to be the reference contemporary full scale measurement device in the sailing yacht engineering research field, to enhance the insight of sail steady and unsteady aerodynamics [1]. The pressure system is described in details as well as the data acquisition process and system metrological validation is provided; furthermore, some results obtained during a wind tunnel campaign carried out at Politecnico di Milano Wind Tunnel, as a benchmark of the whole measuring system for future full scale application, are reported and discussed in details. Moreover, the system configuration for full scale testing, which is still under development, is also described.

Technological advances in wireless networking equipment and atmospheric pressure sensors have enabled the measurement of the pressure distribution across full size sails in normal operation. The pressure measurements may be generated separately on the windward and leeward sides, and on other parts of the rig. Pressure maps of the entire sail can be produced in real-time to provide a detailed time-dependent picture of the pressure distribution, showing the fluctuations and deviations from nominal values due to any changes of the rig, boat motion, or wind. This information is useful in the design process, where sail designers and research aerodynamicists can quantify real-world, full-scale measured differences against computer simulations or alternative sail shapes. It also can be used by sail trimmers to set the best sail shape rapidly and in changing conditions. The pressure sensors are small and lightweight, allowing them to be applied in high density across the entire sail. Laptop software collects and analyses the data, displaying the pressure values and logging the data for post-analysis. This paper provides a descr. of the technologies used to implement the wireless pressure measurement system, presents examples of the data obtained, and compares the measured results with CFD simulations.

The “DYNA” is a research sailing yacht of the TU-Berlin, also called the “Sail-Force-Dynamometer”. She is an entire measuring device for aerodynamic and hydrodynamic forces. The focus in the paper is on measured and computed forces in the standing rigging and in the mastfoot. The aim of the work is to better predict loads and deformations of rigs from high performance yachts for design purposes. The forces in the rig are measured with 20 separate force transducers for mast compression, all shrouds, stays and sheets. A global FEA model of the rig is built up. Geometrical non linear computations for the load cases dock pretensions and sailing upwind with 30° heel are performed. Results are internal forces and deformations of the rig. The loads from the sails are calculated by a load model based on the righting moment of the “DYNA” and the sag angles of the sails. The results of the measurements and the computations are compared with each other.