PRISMATIC HULL TESTS IN REGULAR WAVES IN DIN TOWING TANK

PRISMATIC HULL TESTS IN REGULAR WAVES IN DIN TOWING TANK Begovic Ermina, Boccadamo Guido, Bove Andrea, Caldarella Sebastiano Department of Naval Architecture, University of Naples Federico II, Naples, Italy 1. Introduction Dipartimento di Ingegneria Navale (DIN) of Università degli studi di Napoli Federico II has a towing tank of 137.2 m length, equipped with towing carriage with maximum forward speed of 10 m/s to perform the model tests for ship resistance prediction. This dimension of towing tank and carriage maximum speed allow relatively huge models and very good tank-sea correlation. Resistance and powering characteristics have been conducted both for conventional ship and for fast planning hulls. Furthermore, multi hull configurations like catamaran, trimaran and pentamaran ship models have been subject of research during last years. State of the art in naval architecture indicates that the significant improvements in ship resistance characteristics were obtained using the optimised hull forms and consequently the cruising speed was increased. On the other hand, increasing speed and security of vessels calls for a better understanding of the seakeeping so ship behaviour in rough water become one of the principal interests of scientific community both as development of numerical prediction method and as experimental determination of ship responses. Considering seakeeping of ships means practically to constrain the attention mainly at vertical accelerations, relative vertical motions between ship and waves, slamming, water on deck and wave bending moments and shear forces. Vertical motions and accelerations result in loads on structures, cargo and equipment and are the main reason for seasickness. It is evident that this aspect will be the most important for the passenger ships in order to increase the comfort on board. Relative vertical motions are used to evaluate the possibility and damage due to slamming and water on deck and therefore are important to be improved the safety of ship. As regard the exciting loads (i.e. wave bending moments and shear forces) generated in the interaction of ship advancing at “constant” speed in confused sea it is of paramount importance for the structure to be dimensioned appropriately. Within the frame of the Competence Regional Centre “Transport”, a project financed by the Campania Region (Mesure 3.16 POR Campania 2000- 2006), started in November 2002, to develop a research structure equipped with some technological laboratories and capable to integrate the competences of Universities and Research Corporations, acting in the Campania Region, DIN was one of Departments of University of Naples Federico II selected to get financial resources for technological development and improvement of laboratory facilities. At towing tank new electric feeding system has been installed and new acquisition system has been developed. Recently, a wave maker designed by Edinburgh Designs Ltd, chosen in open bid, has been installed at DIN towing tank with the aim to extend the tank possibilities also to seakeeping tests. In this work, the first seakeeping tests conducted at DIN towing tank equipped with new wavemaker for the prismatic hull form, typical for the planning ships are presented. The idea for the project demonstrator was to highlight the possibility of towing tank – towing carriage – wavemaker for the prediction of high speed craft behaviour in rough sea, as it is considered one of the most important subject of scientific research. For the validation of ship performance in rough sea, the vertical motions i.e. heave and pitch have been considered as the most influencing for comfort on board. The tests are relative to 28 m length high speed craft cruising at speed of 30 knots in regular waves.