This study deals with the estimation of the compressive strength of carbon fibre reinforced plastics composites used in yacht racing. This property is one the key design parameters in marine engineering. The mechanism of fibre micro-buckling as well as a structural effect including the neighbouring plies of the unidirectional ply and the deformation gradient linked to the the mechanical loading are taken into account to propose an analytical model for estimating this property. The parameters involved require a number of experiments to characterise the microstructure at the level of components (fibre, matrix, ply) and the mechanical behaviour (elastoplasticity). Some of them can be estimated using a micro-mechanical approach. It is shown that estimations and experiments show good agreement on two cases: one with a constant deformation gradient, the other one in pure compression. The paramount influence of the initial misalignment of the fibre is highlighted.

Running aground with a sailing yacht can result in significant damage to the structures of a yacht; particularly at high speeds. The prediction of grounding forces and an associated maximum speed is therefore an important precaution measure to remain inside the structural design envelope; to obtain robust structures at predictable grounding scenarios. Since current classification rules do not explicitly regard the vessel’s speed, an improved method of predicting grounding forces is desired. The aim of this work is to investigate the forces that act on a sailing yacht during grounding. A nonlinear finite element analysis of a large sailing yacht is performed, that accounts for plastic deformation of the keel bulb, elastic deformation of the keel fin and hull as well as hydrostatic restoring forces. The influence of the yacht’s initial velocity, draft and ballast/displacement ratio is investigated. Furthermore, the grounding force experienced by a yacht with a crashworthy bulb is examined.

This paper describes insights into keel and rigging loads obtained through a data acquisition system fitted on the fleet of Volvo 65 yachts during the 2014-2015 Volvo Ocean Race. In the first part, keel fin stress spectra are derived from traces of canting keel ram pressures and keel angle; these are reviewed and compared against equivalent spectra obtained by applying methods proposed by Det Norske Veritas - Germanischer Lloyd (“DNVGL”) guidelines and the ISO 12215 standard. The differences between stress spectra and their validity are discussed, considering two types of keel: milled from a monolithic cast of steel, and fabricated from welded metal sheets. The second part discusses predicted and actual rigging working loads for the Volvo 65 yachts, and considers how safety factors vary between design loads proposed by DNVGL and actual recorded loads.