Small waterplane area ship models: Re-analysis of test results based on scale effect and form drag

The first systematic model series of hulls with small waterplane area (both single hulls and twin-hulls) was designed and tested in Krylov Shipbuilding Research Institute in the middle of the 1980's. The series was intended to cover a broad range of Froude numbers, hull aspect ratios, design drafts, and spacing between hulls. In the present paper, these test results are re-analyzed by accounting for the scale effect in the form drag, obtained from the comparison with test data of larger out-of-series models. Illustrative results are also given for the influence of the cross-section hull shape, strut configuration, and shifted hulls on the residual resistance and for dynamic trim and draft. Some data are compared with those of the later series tests of twin-hull models with small waterplane area carried out in HSVA, Germany. Factors influencing the residual resistance of ships of this type are discussed.