Global and slam loads for a large wavepiercing catamaran design

Abstract Prediction of design loads for small high speed commercial craft has traditionally been governed by classification society, rule based formulae. Larger high speed vessels, particularly those greater than 100 m in length, require validation of rule based design loads. Validation methods include model tests or hydrodynamic studies using computer based motion and loads software. This paper presents the results of studies into the calculation of global loads for a 112 m, wavepiercing catamaran design. In particular, the preliminary design approach for assessment of loads is discussed. Longitudinal bending and pitch connection moment loads are derived from linear and nonlinear motion and loads software packages FASTSEA, SWAN and BESTSEA. The computed results are compared with rule based loads and empirically derived loads based on full-scale measurements from similar craft. Local wet deck slamming loads are discussed with reference to current rule based formulae and results of full scale tests on similar vessels. The effect of high local slam loads is discussed and how these loads may influence the design process. Conclusions are drawn on the presented results concerning the interaction of global and local loads in the design of a 112 m wavepiercing catamaran for Incat shipbuilders in Hobart, Australia.