Performance prediction for high speed craft

Abstract

Generally the performance of the high speed craft can be divided into six main components such as resistance and powering, propulsion, dynamic instability, seakeeping and manoeuvring. Performance prediction on high speed craft especially in planing hull is complicated due to complex combination of ship behaviour in rough sea condition. The performance of high speed craft is becoming more important due to their various functions and purposes to marine community which is unable to be predicted using conventional methods. The fundamental of this research is to study the two main components of the vessel i.e. resistance and seakeeping quality by incorporating stern foil at aft portion planing craft (M Hull) that gives significant effect to the performance of the vessel. Theoretically, stern foil has a similar function with transom flap, trim wedges and trim tab which is to reduce the resistance and also as a damping for motion reduction. In the scope of resistance performance for this vessel with stern foil, the Savitsky and two dimensional Methods are used for resistance prediction at different angle of attack. While Computational Methods i.e. SEAKEEPER program was applied to seakeeping prediction in regular wave (head sea). Both result of resistance and seakeeping performance prediction was validated by conducting model test for the model with and without stern foil. The performance of ship model with stern foil gives a positive performance in term of seakeeping quality at constructive resistance. By adapting with stern foil the heave and pitch Response Amplitude Operator (RAO) trim down by 4.0% and 18.91% respectively. Furthermore, the reduction of forward and aft acceleration RAO also occurs concurrently which the decreasing of both acceleration are 21.10% and 6.14%.