This chapter deals with the linear response of the hull girder to primary loads. The primary structure is defined and vertical bending axial and shear stresses are determined. The theory of shear stresses in open and closed sections is presented. Deflections related to both axial and shear stresses are discussed and hull girder longitudinal bending theory is validated against full-scale measurements. Initial design considerations for longitudinal strength are discussed in relation to rule requirements and the calculation of the section modulus of a transverse section. The combined effect of axial bending and shear-induced axial stresses is discussed and shear lag is defined and calculated. The effective breadth method is described. Horizontal bending of the hull girder is discussed next. The response of the hull girder to torsional loading is discussed next. Torsion theory of thin-walled sections is presented and this leads is applied to the analysis of sections consisting of a number of closed cells subjected to uniform torsion. The last section deals with the determination of critical regions of the hull girder for longitudinal strength with respect to yielding, given that the stress field is multiaxial, longitudinal bending stresses being one component.