The time-varying influence of a sailor’s position is typically neglected in dinghy velocity prediction programs (VPPs). When applied to the assessment of dinghy race performance, the position and motions of the crew become significant but are practically hard to measure as they interact with the motions of the sailboat. As an initial stage in developing a time accurate dinghy VPP this work develops an on-water system capably of measuring the applied hiking moment due to the sailor’s pose and compares this with the resultant dinghy motion. The sailor’s kinematics are captured using a network of inertial motion sensors (IMS) synchronised to a video camera and dinghy motion sensor. The hiking moment is analysed using a ‘stick man’ body representation with the mass and inertial terms associated with the main body segments appropriately scaled for the representative sailor. The accuracy of the pose captured is validated using laboratory based pose measurements. The completed work will provide a platform to model how sailor generated forces interact with the sailboat to affect boat speed. This will be used alongside realistic modelling of the wind and wave loadings to extend an existing time-domain dynamic velocity prediction program (DVPP). The results are demonstrated using a single handed Laser and demonstrate an acceptable level of accuracy.

The behaviour of sailing boats in open sea is strictly related to their hydro and aerodynamic performances and to the wide range of loads acting on the hull and rigging system. Their evaluation could be done only by a careful seakeeping analysis with particular attention to the acceleration loads caused by hull motions which can create severe problems to mast and rigging up to extreme consequences such as dismasting. The main reasons of dismasting are related both to human errors and to the lack of load knowledge; as a matter of fact Classification Societies' Rules are quite poor about this subject and the structural design if often committed to the designer experience. The aim of this work is to investigate on the hull dynamic responses which mainly influence the mast and rigging loads with particular attention focused on the pitching behaviour of the vessel. With this goal in mind the seakeeping behaviour of a number of sailing yachts, different each other in sizes and typology, has been investigated. Despite the small size of the database, the achieved results allowed to formulate a preliminary simplified method to estimate the pitch Ratio Amplitude Operator (RAO), based only on the boat length. From the pitch RAO knowledge a very rough and quick formulation to evaluate the longitudinal acceleration in the mast centre of gravity has been obtained.

Current methods for assessing slamming of ships in head seas are generally based on constant-velocity wedge impact results for each hull section. A 2D Smoothed Particle Hydrodynamics (SPH) method is described for calculating slamming loads on realistic hull section shapes and impact velocity profiles. SPH is a particle-based method that is mesh-free and is therefore able to accurately simulate large free surface deformations such as jets and splashes, which are an important factor in slamming events. It is shown that large slamming pressures are predicted on wedge shaped hull sections and the concave part of flared monohull sections. Similarly, cross-deck slamming of catam aran hulls can produce large slamming pressures at the top of the arches. The nature of relative vertical velocity profiles during slam events is also discussed. Hull sections with varying velocity profiles are modelled using SPH to show the effect on slamming pressures as compared to the commonly used constant velocity profile.