A. Scamardella

Optimization of Mooring Systems for Floating Offshore Wind Turbines

The paper deals with the optimum design of mooring systems, with chain cable catenary line configuration, for Floating Offshore Wind Turbines with tri-floater support structure in deep waters. Operational and extreme climate conditions are assessed for a candidate location in southern Tyrrhenian Sea, determining wind, wave and current loads. The platform response is assessed in terms of static loads due to turbine thrust, wind, current and steady drift forces. The platform dynamic offset is determined considering both wave-frequency linear and low-frequency second-order motions. Two different mooring systems with 9 (equally spaced) and 11 (non-uniformly spaced) lines are selected in order to minimize the total mass; the incidence of both line number and pattern is appreciable and there is wide space to achieve considerable weight reductions, so increasing the overall wind farm cost-performance trade-off.

The overall motion sickness incidence applied to catamarans

Abstract The Overall Motion Sickness Incidence is applied to the hull form optimization of a wave piercing high-speed catamaran vessel. Parametric hull modelling is applied to generate two families of derived hull forms, the former varying the prismatic coefficient and the position of longitudinal centre of buoyancy, the latter instead the demi-hull separation. Several heading angles are analysed in a seaway, considering all combinations of significant wave height and zero-crossing period under two operating scenarios. The optimum hull is generated and vertical accelerations at some critical points on main deck are compared with the parent ones. Finally a comparative analysis with the results obtained for a similarly sized monohull passenger ship is carried out, in order to quantify, by the OMSI, the relative goodness in terms of wellness onboard of monohulls and catamarans, as a function of sea states and operating scenarios.