This thesis to investigate and structural performance of two types of ship's components, namely: (i) top hat beam panels and (ii) cross-stiffened hat-shaped composite panels. These were tested experimentally and analysed theoretically using the finite element method. First a number of coupons were tested to obtain stiffness and strength and fibre content of the layers of the composite structures. Then two types of ship's components have been tested under static loading conditions that may be encountered in service. Structural stiffness issues and their dependence on lay up have been explored. The progressive nature of failure, from matrix cracking through to final collapse was detailed. Numerous strain gauges and digital dial gauges were used to collect important information during the experimentation. Finite element models were generated by using the commercial finite element (FE) code ANSYS for these structures. The results have been validated against experimental results directly in the case of global load/definition results. The finite element derived failure stresses were also compared with the material failure data, at experimental failure loads. This enables further understanding of the internal stress pattern and helps identify the regions of weakness within the structural element which are most susceptible to damage under a variety of loading conditions. Reasonable correlation was found on all accounts. A detailed parametric study has been conducted to examine the influence of geometric variables and material choice on the structural performance of top hat stiffeners.