Running Attitude of High-Speed Fishing Boats

Abstract

When ships run at the high speed, the variation of the sinkage and trim cannot be ignored. Recently the Froude number of small fishing boats becomes larger and larger. So we must consider the running attitude to predict the seakeeping quality and manoeuvrability of high-speed fishig boats. This study dealed with this problem from the hydrodynamic point of view. Theoretical calculation based on the slender body approximation was applied to typical high-speed fishing boats. The two dimensional boundary value problem of the slender body theory was solved by using the integral equation method. The three dimensional correction involved the free surface effect. The calculated results are compared with the corresponding experimental values. Both calculated and experimental values indicate the drastic increase of trim (F_n=0.4∼0.5) and the floating tendency (F_n>0.5). And further, the slender body theory made it clear that these phenomena are caused by the free surface effect.