Ship and box girder structural geometry contains theoretical stress singularities, and certainly involve large local concentrations of stress and strain. These geometries are often subject to finite element (FE) analysis but the selection of the modelling required and the interpretation of the results are not straightforward. Some guidance is available but it is generally founded on limited comparisons with experiments rather than on an overall analysis of the problem and the guidance is almost certainly not generally applicable. This paper reports some work started, with a small amount of funding from the EU MARSTRUCT network, to try and provide a good theoretical foundation for finite element analysis of these details. It concentrates on the analysis of a simple right angled cruciform corner with no: bending, thickness changes, overlapping plates or weld reinforcement geometry. Also ignored are effects of mean stress and residual stress. Some characteristics of the stress field and its effect on S-N and Paris Law crack growth calculations are investigated. The results are presented in terms of size dependent SCFs for S-N fatigue analysis and Y factors and 'additional defect sizes' for fracture mechanics crack growth calculations.