Structural responses of high performance sailing yachts to slamming loads

Experimental measurements of transient strains, local accelerations and pressure were undertaken on the IMOCA Open 60' class sailing yacht Paprec-Virbac III, and on a replica hull panel section tested in a laboratory slam testing facility. The approximately 1m x 0.7m panel for laboratory testing was manufactured on a mould taken from the plug used for the vessel construction, ensuring that the panel had identical curved geometry to the vessel. The laboratory panel included two stringers as on the same region of the vessel. An instrumentation layout including arrays of resistance strain gauges, accelerometers and a transient pressure transducer was used. Linear displacement transducers were used to measure panel deformations during the laboratory tests. The laboratory testing was undertaken at a range of constant impact velocities from 0.5 to 3m/s using a Servohydraulic Slam Testing System. Sea-trials were undertaken in the Hauraki Gulf, Auckland New Zealand. There was good qualitative agreement between the field and laboratory measurements in regard to timing and relative magnitudes of strains at different positions on the structure. Results demonstrate that the hull structure undergoes very complex transient deformations during the slamming events.