RESISTANCE CHARACTERISTICS OF A HIGH-SPEED CATAMARAN AND ITS APPLICATION

The interference of wave system between demihulls of catamaran is analysed. It is proved that the demihulls interact on each other with positive or negative interferences. Only in negative interference condition, the catamaran resistance is lower than that of two separate demihulls due to the advantageous transverse waves generated by two demihulls.Based on the resistance test duta of high-speed catamaran with three different forms at varying spacing ratio k/b and displacement-length ratio / (0.1L)3, the influences of / (0.1 L)3, k/b and ship form on the resistance of catamaran are discussed, and the formulas for calculating Fr0 (the Froude number of starting point of negative interference,above which the negative interference will occur) and FrB (the Froude number with flow blockage between demihulls, above which the resistance of catamaran will greatly increase)are also given. By using the calculation formulas, the apropriate speed, k/b and / (0.1L)3 can be found to satisfy Fr0Fr FrB, and the catamaran will thus operate at a lower resistance in negative interference condition.