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The total resistance of ship in waves is composed of calm water resistance and added resistance in waves. The added resistance in waves is one of the main causes of an involuntary speed reduction of a ship. It may cause a significant increase in ship resistance and consequently increased fuel consumption and carbon dioxide emission, especially at heavier sea states. Thus, the added resistance is very important from both an economic and environmental point of view. In this paper, an increase in fuel consumption is calculated for container ship on a typical North Atlantic route. The calm water resistance is calculated utilizing Computational Fluid Dynamics based on the viscous flow theory at model scale and the obtained results are extrapolated to full scale. The added resistance in waves is calculated using three-dimensional panel code based on the free surface Green function, for the sake of simplicity. It is calculated at regular waves and the mean value of the added resistance at certain sea states is obtained by means of spectral analysis. Two-parameter Bretschneider wave spectrum recommended for the North Atlantic, defined by significant wave height and zero crossing period, is used in the spectral analysis. The obtained results may provide valuable insight into the important environmental issue of pollution reduction.

The total resistance of ship in waves is composed of calm water resistance and added resistance in waves. The added resistance in waves is one of the main causes of an involuntary speed reduction of a ship. It may cause a significant increase in ship resistance and consequently increased fuel consumption and carbon dioxide emission, especially at heavier sea states. Thus, the added resistance is very important from both an economic and environmental point of view. In this paper, an increase in fuel consumption is calculated for container ship on a typical North Atlantic route. The calm water resistance is calculated utilizing Computational Fluid Dynamics based on the viscous flow theory at model scale and the obtained results are extrapolated to full scale. The added resistance in waves is calculated using three-dimensional panel code based on the free surface Green function, for the sake of simplicity. It is calculated at regular waves and the mean value of the added resistance at certain sea states is obtained by means of spectral analysis. Two-parameter Bretschneider wave spectrum recommended for the North Atlantic, defined by significant wave height and zero crossing period, is used in the spectral analysis. The obtained results may provide valuable insight into the important environmental issue of pollution reduction. [ABSTRACT FROM AUTHOR]

The present study investigates the use of Artificial Neural Networks (ANNs) for the resistance prediction of hullforms designed according to the MARAD Systematic Series. This series comprises 16 full hullforms, specifically designed for use as bulk carriers and tankers. Experimental data for the residual resistance coefficient of these hulls provided by MARAD in a series of diagrams have been used to train and evaluate a series of neural networks aiming to estimate the residual resistance coefficient of ships designed according to the MARAD Series. The adopted procedure along with the obtained results are presented and discussed. [ABSTRACT FROM AUTHOR]

Ships have become the main means of transportation in the world trade. With paying more attention to global warming problems, the Greenhouse Gas (GHG) emission reduction of ships has been extensively studied. Trim optimization is taken as a GHG reduction technology. Considering trim optimization of calm water resistance is energy-saving, but it cannot always be the best state in practice affected by wind and waves. The difficulty on trim optimization in wind and waves is the calculation of added resistance. On account of the high-cost and long-period, the experimental method and Computational Fluid Dynamics (CFD) method are ill-suited for trim optimization. In this paper, high-efficiency and high-accuracy Taylor Expansion Boundary Element Method (TEBEM) and ITTC two-parameter spectrum are used for calculating added resistance in regular and irregular waves respectively. Wind load is estimated by empirical formula. Trim optimization of a 300K-ton VLCC oil tanker on a typical route is studied. Compared with calm water trim optimization, it is found that dynamic trim optimization in wind and waves can save about 949.3 kg fuel and the fuel saving potential is about 0.04%, based on the average sea states over the whole route. Therefore, dynamic trim optimization during navigation is more beneficial. • Taylor Expansion Boundary Element Method is used to solve added resistance of VLCC oil tanker at different trim angles. • The sea states of a typical route of VLCC oil tanker is analyzed statistically. • Dynamic trim optimization of VLCC oil tanker can be more beneficial to reduce CO 2 at different sea states on a typical route. [ABSTRACT FROM AUTHOR]

Results of ship resistance predictions obtained from towing tank experiments are affected by the method used to extrapolate from a model scale to a ship scale. Selection of method to determine a form factor is subjective and the extrapolation method is accurate for typical hull forms. For innovative hull forms the proper method for calculating the form factor is questionable. Moreover, the influence of the extrapolation method can be equally as important as the influence of a redesigned hull form itself. The paper presents novel numerical and experimental methods used to predict ship's total resistance in calm water. The results determined by towing tank experiments, full-scale CFD simulations and ship's sea trial measurements were compared. Depending on the method used, the determined form factor differed by 19%. As a result, the predicted calm water resistance varied from −6% to 11% relatively to sea trials data. For innovative hull forms in particular, full-scale CFD simulations should support the towing tank method. The results calculated by full-scale CFD varied from −10% to 4% relatively to sea trials data depending on the assumptions on hull roughness and turbulence model. The towing tank testing and full-scale CFD simulations can provide similar accuracy. • Ship resistance prediction from CFD shall support towing tank testing. • Extrapolation from model scale to full scale cause high uncertainty. • Form factor calculated by different methods varied by 19%. • Resistance from towing tank varied from −6% to 9% relatively to sea trials data. • Resistance from full-scale CFD varied from −10% to 4% relatively to sea trials data. [ABSTRACT FROM AUTHOR]