OPERATIONAL EFFICIENCY AT SEA OF A NEW OCEANOGRAPHIC VESSEL AT THE DESIGN STAGE: A DETAILED STUDY OVER THE CENTRAL MEDITERRANEAN SEA USING MEDIUM RESOLUTION HINDCAST WAVE DATA

The Italian Navy is currently developing a new hydro-oceanographic vessel for the Mediterranean sea and neighbouring areas. Among other requirements, the ship is asked to withstand a given sea state during the operations, measurements or transfer. A detailed theoretical investigation has been undertaken adopting state-of-art methodologies and numerical tools able to estimate the behaviour of the ship at sea over a grid of geographic cells belonging to the central Mediterranean sea. In particular, the seakeeping performance of the ship in terms of motion, velocity and acceleration at given positions on board has been analysed with incident wave data (directional spectra) derived from a hindcast wind-wave database developed at the University of Trieste. The database covers the central Mediterranean sea with cells of 60 nm x 60 nm and the wave data consist of hourly wind-wave time series over the period 1989-2008. The paper presents the overall methodology, with some hints of the met-ocean and seakeeping models. The results obtained by the application of the procedure to a preliminary design of the ship and hull shape still under development are presented in details.