Added Resistance of a VLCC in Short Waves

Abstract

In quantifying speed loss due to waves, added resistance in short waves plays an important role, because most of the time a ship travels in small sea states. It is known that added resistance in small sea states is difficult to predict accurately. In order to study improved prediction methods, numerical calculations and experiments on added resistance of a VLCC in head waves have been carried out. This paper explores a radiated energy method, an asymptotic method (Faltinsen 1980) and their combination. In addition, experimental determination of added resistance in short waves is challenging. The paper discusses the sensitivity of the results to the quality of the waves, and it is also discussed how different approaches for measuring and analyzing waves might influence the results. A novel procedure for carrying out and analyzing added resistance test results is described, and the table for the precision error of the experiment is given. Finally the results from experiments and numerical calculations are compared. The results show that the added resistances predicted by th e combined numerical calculation are a bit smaller than the experimental results at lower Froude number, while they are in good agreement at higher Froude number.