Measured stresses and deflections are compared with calculated ones. Method to calculate the correct bending moment at lift by the stern, considering the effect of inertia force of virtual mass, is established. The values of virtual mass coefficient kw lied between 2.23.0. The contributions of the super structures to the longitucinal strength and rigidity are discussed. Strength of stress concentrated parts at double bottom is examined and the parts are proved to be safe from fatigue failure.