Structural re-design of a composite pleasure craft with direct and numerical calculations

In this paper, the structural re-design of a 25-meter patrol boat build in aluminium light alloy is presented due to a vessel retrofitting activity; the new vessel has to maintain the same hull shape of the original patrol boat but it will be intended to be used as a fast pleasure craft made in composite. For this research three different composite material has been studied, proposing different structural layouts and scantlings according to the vertical accelerations proposed by Classification Societies. The structural weight has been considered the main driving parameter for the scantling; a first optimisation has been carried out by comparing the use of different materials (GRP, carbon composite and an hybrid solution) with direct CS calculation. The best solution has been further optimised by a structural Finite Element calculation that highlighted possible plies removal in the lamination stack of the hull.