Cooperative Resistance Tests with Geosim Models of a High-Speed Semi-Displacement Craft

A resistance test program of a high-speed semi-displacement craft was performed in sixteen towing tanks (including one circulating water channel) involving thirteen geosim models of 0.4 to 4 meters in length. This work forms a part of the tasks of the High-Speed Marine Vehicle Committee of the 19th ITTC. Analysing sixty three data sets, the following conclusions are obtained. The scale effect is not found in the wave resistance, and on the other hand, it appears in trim and spray calculation. The form factor of frictional resistance can be determined even at high Froude numbers, by the method suggested by Hughes as a function of Froude number. The application of turbulence stimulator is necessary in resistance tests even for larger models at high-speed. Appropriate turbulence stimulator for semi-displacement hull forms should be developed. The characteristics of semi-displacement hull forms in the range of medium Froude numbers (Fn<1.3) are similar to those of displacement hull forms in many points. This means that the ITTC 1978 power prediction method, with partial modifications, would be applicable to this type of high-speed craft.