Interests in high speed cargo ship are increasing with the growing importance of world trade. In addition, high speed ship has tendency to increase the utility value in various special purpose ships such as patrol boat, leisure boat, etc. The category of high speed ship includes planing craft, hydrofoil, ACV, SES & etc. Hydrodynamic or aerostatic support types are mainly used for small sized naval vessel, passenger boat, utility boat, leisure boat, and others, due to the limitation of seaworthiness and enlargement. The planing craft is designed specifically to achieve comparatively high speed on the surface of the water. Especially, planing craft is so popular as holding 80% of the research for high speed boat.
On the one hand, the performance verification equipments of crafts are the circulating water channel and towing tank. But model-test of the high speed planing craft has a difficulty in performance verification because of the relatively small scale ratio of the ship-model and restricted by flow velocity of the circulating water channel and X-carriage velocity of the towing tank.
In this paper, I will describe the hydrodynamic characteristics of planing hull, discussing the effect on planing performance. In order to verify performance of high speed planing craft, at-sea model test techniques were used. Also, the hull form development and resistance performance of small high speed planing craft were studied with experiments of using at-sea model test techniques. This process explains the process of hull form development for principal performance for 3 high speed planing crafts, which are gathering great interests lately. To verify the proposed model test method, resistance measuring or load cell used calibration and it showed ±2.5% error in comparison to circulating water channel resistance result for 5m class rescue boat.
In general, the stepped hull craft has high fuel efficiency thanks to the resistance reduction by a small wetted surface area without corresponding stepped hull craft. But It has a tendency to show bad rolling performance by reduced wetted area in stern. The model tests for 3 planing crafts which the number of step and with & without attached a stern body and with & without air injection in bottom were performed to compare the effect of principal performance using at-sea model test techniques.
In conclusion, this step and air injection in bottom are effective in reducing in wetted surface area of a ship. It was invested that almost 5～10% of the total resistance of model ships at designed speed can be reduced. And the planing craft attached a stern planing body was invested effective to reducing roll angle and pitch angle.