The first report on the present title showed the results of model tests that were performed in order to examine the behavior of double-hull structures simulating side structures of offshore-oil tanks during a collision. There it was seen how the failure modes varied with the change in scantlings of structural members. A semi-analytical procedure, based on the model tests, was developed to evaluate the energy absorption characteristics of the individual components of the structures. However, it was felt necessary to test a series of models of different sizes so as to confirm the validity of the procedure. In this paper, therefore, the static failure tests with the variation of the scales of models were carried out, for the purpose of examining the scale effects on failure modes and similarity principles of the energy absorbed during structure failure. Although the breaking load of the outer plate showed deviations from law of similarities, the semi-analytical formula, on the whole, was found to be valid for forming an estimate of the energy absorbed before a ramming bow penetrates to the inner hull of the double-hull structures. The energy absorption efficiency that is defined by the absorbed energy per unit volume of structural members is discussed by using the formula.