A reliable investigation that allows an accurate prediction of the total resistance coefficient of a high-speed" deep-V" catamaran in shallow water is obviously required. The Computational Fluid Dynamic simulation proposed approach is aimed to attain this precise outcome, while a hydrodynamic description of the rationale underlying behind the results is explained. Several effects of lateral separation ratios (S/L) and longitudinal staggered position (R/L) against a wide range of Froude numbers (Fr) from 0.5 to 1.0 were considered. The results revealed that the general increase in Fr is proportional to the increase of total resistance. In contrast, the increase of lateral separation ratios dealt with less total resistance coefficient, where the sufficient reduction of C T was about 11% as the Fr increase from 0.5 to 0.6 for S/L=0.3. Regardless of R/L ratios, the results showed the subsequent increase of Fr from 0.5 to 1.0 was also proportional to the total resistance, where the maximum increase of RT was about 21% as the Fr increase from 0.6 to 0.7. In addition, the increase of R/L ratios has led to sufficient increment of C T by 1.5% as the Fr increase from 0.9 to 1.0. Generally, the increase of S/L and R/L ratios have similar effects on the total resistance characteristics. This CFD simulation results are very useful as preliminary data for the ship resistance, which is mainly required for predicting a ship powering accurately.

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Due to the highly complex phenomenon of a ship towing system associated with the presence of a dynamic nonlinear towline tension, a reliable investigation allowing for an accurate prediction of the towed ship's course stability is obviously required. To achieve the objective, a Computational Fluid Dynamic simulation approach is proposed by investigating attainable and precise course stability outcomes, whilst a hydrodynamic description underlying the rationale behind the results is explained. Several towing parameters such as various towline lengths and tow point locations with respect to the centre of gravity of the barge have been taken into account. Here, tug and barge is employed in the simulation as the tow and towed ship, respectively. In addition, a towing velocity is constantly applied on the tug. The results revealed that the course stability of the towed ship increases in the form of more vigorous fishtailing motions as the towline length subsequently increases from 1.0 to 3.0. Meanwhile, the increase of tow point location from 0.5 to 1.0 leads to a significant improvement in the course stability of the towed ship, as indicated by the reduction of the sway and yaw motions by 227% and 328%, respectively. It is concluded that the increase of tow point location is a recommended decision to achieve a better towing course stability for the barge.

Investigation of a ship towing system performance in waves incorporated with an asymmetrical towline configuration is necessarily to be studied to ensure a towing safety of navigation. To achieve the objective, this paper presents the ship towing motion performance in waves using Computational Fluid Dynamic (CFD) approach. Here, the heave and pitch motions of the towed ship so-called barge has been analysed, where several effects of the towing angle and towing speeds have been taken into account. In the calm water condition, the results revealed that the increase of tow angle was proportional with the sufficient reduction of the sway amplitude motion and inversely proportional to her yaw motion. The increase of the asymmetrical tow angle, however, has led to increase her sway motion amplitude in wave condition and conversely reduced the tow speed increased. In addition to the pitch motion characteristic, it subsequently increased by 12.1% as the tow angle raised from 25° to 35°; meanwhile the pitch motion of barge has by 10.2% as the tow speed increased from 0.655 m/s to 0.728 m/s. This CFD simulation is very useful as the preliminary prediction on the heave and pitch motion characteristics ensure a safety navigation of a towed ship in waves.

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