The forced rolling model test has been studied for the oil tanker under three rolling amplitudes with rolling period from 0.8 s to 20s by using self-developed equipment and control system of the rolling test. The forced rolling moments and the phase shifts between the rolling moment and the rolling motion is comprehensively studied under the different rolling periods at zero sailing speed. The test results show that the rolling moment firstly decreases with the increase of the rolling period until it reaches to the minimum rolling moment when the test period approaches to the natural rolling period, and then increases gradually. Finally the rolling moment will remain constant when the rolling period becomes very long and the ship rolls slowly. The rolling moment is multiple relation with the rolling amplitude with the same rolling period and the different amplitudes. The added inertia increases linearly with the reduce of the rolling period, but the rolling damping increases nonlinearly with the increase of the rolling amplitude.

With the implementation of IMO Regulation on Minimum Propulsion Power and the revision of the ISO-15016 document concerning the sea trial speed correction method, the study of the added resistance in the waves that arises wide concerns has become one of the hot issues and the difficulties in the current study of the ship sea-keeping performance. Although the added resistance in the head sea conditions has been widely studied internationally, no substantial breakthrough has been made for the prediction of the added resistance in any wave direction, such as in the oblique sea and the following sea, yet. The methods for the numerical calculation and model experiment of the added resistance in any wave direction are firstly introduced. Then the numerical calculation and the model experiment of the added resistance in any wave direction are carried out for the 20 000 TEU very large containership. The numerical prediction method is verified and validated by comparison with the results calculated by the commercial software and the experimental results from Maritime Research Institute Netherlands (MARIN). It shows that the calculation results in the current study are more accurate than the results calculated by the commercial software, and the current model experiment method is feasible. The results can be used in the prediction of the added resistance of the ships in any wave direction, and thus the correction of the sea trial speed as well as the check of the regulation on the minimum propulsion power, which can provide good engineering application value.

The hydrodynamic performances of a contra-rotating propeller and a contra-rotating rudder propeller are predicted by using the improved delay detached-eddy simulation (IDDES) model and sliding mesh method based on the OpenFOAM software. The thrust coefficients are analyzed by the fast Fourier transform (FFT) method. The numerically calculated thrust coefficients, torque coefficients and propulsion efficiencies of the contra-rotating propeller are compared with the model test results with the errors of 3%, 2% and 5%, respectively, indicating the validity of the numerical method. The numerical results of the contra-rotating rudder propeller show that the pressure drag is the main component of the drag of the pod and strut, and there is a reverse flow at the front of the strut. The strut, therefore, can be optimized from the two aspects. The strut and the pod can also reduce the vibration caused by the bearing force.