In Sweden, six 72 meter navy ships are produced using sandwich structures. The skins are carbon fiber/vinylester and the core is primarily cross-linked PVC foam. The production technique is vacuum injection molding of large sandwich panels. Several material issues have been studied during the course of ship development. Compression strength is one important problem where the present carbon fiber non-crimp fabrics (NCF) and vinylester resins seem to give much lower data than prepreg-based composites used in aerospace applications. Compression testing and microscopy techniques are used to study this effect. Lower matrix yield strength, higher fiber waviness and poor testing techniques were shown to be the reasons for low compressive strength. The improved understanding of compressive failure in NCF composites also increased confidence in ship structure performance.