Numerical evaluation of different hull structures for a GRP motor yacht

ABSTRACT: A joint research between AZIMUT Shipyards and the Dipartimento di Ingegneria Navale of the University of Genova (DINAV) has been issued in 2004 to assess in detail the influence of Classification Society Rules on GRP yacht design. Particular emphasys has been devoted to the definition of mechanical properties of composite materials and to the scantling rules of medium size hull structures . In this paper the second investigation is presented with particular reference to the “Design and Construction of Pleasure Boats” Rules of RINA, the Italian Classification Society. The interest was particularly addressed towards medium size motor yachts in the range below 24 meters length and an AZIMUT 60’ motor yacht has been chosen as case study. For this vessel different versions of hull structures have been determined by parametrically varying the main scantling variables. For each of the obtained structures, the correspondent finite element model has been created by the FEM code NASTRAN. Finally the safety factors of RINA scantling formulas have been evaluated by determining the stress levels of all models and comparing them with the RINA equivalent stress level