Optimal sail design and rig tune of a J70 are studied using RANS CFD, FEA and a low cost data acquisition system. In one design racing sail design and rig tune are the biggest variables that can be changed from one boat to another and figuring out the correct balance between the two is critical to good performance. One design sails are challenging to model computationally because they deform under sailing loads and are sensitive to rig tune. Using accurate flying shapes in CFD models is key to picking out the slight aerodynamic differences in sail and rig setup. We develop a system to monitor sail flying shapes, trim, rig load and performance data based on cheap hardware components and open-source data processing libraries. The sail shape and rig data are used to drive the geometry used in the aerodynamic RANS CFD simulations. A series of J70 sails and rig setups with known performance characteristics are modeled and tested on the water, and the proposed camera system was able to differentiate between different rig tunes and recreate them in CAD software. CFD force data and post processing information is studied to understand what are the optimal aerodynamic characteristics and how are they effected by sail design and rig tune.

It is with much pleasure that we write the editorial for this special issue devoted to Yacht Engineering, arising from the 3rd International Conference on Innovation in High Performance Sailing Yachts (Innov'sail2013), held in Lorient, France.

This paper describes the method used by the Italian Classification Society RINA to develop new Rig Certification Rules. These Rules have been mostly based on failures observation, and their starting point has been a systematic study of dismastings occurred on boats of various types and sizes. Examining many of these events, typical collapse modes have been identified, and specific solutions have been proposed. Within this study a first attempt to a novel rig “dynamic” structural assessment has been developed taking advantage of a new integrated (CFD+FEM/FEA) analytical tool. Theoretical analyses have been compared with experimental data collected during extensive sailing tests on board a 94ft yacht.