Voyage optimization is a practice to select the optimum route for the ship operators to increase energy efficiency and reduce Green House Gas emission in the shipping industry. An accurate prediction of ship operational performance is the prerequisite to achieve these targets. In this paper, a modified Kwon's method was developed to predict the added resistance caused by wave and wind for a specific ship type, and an easy-to-use semi-empirical ship operational performance prediction model is proposed. It can accurately predict the ship's operational performance for a specific commercial ship under different drafts, at varying speeds and in varying encounter angles, and then enables the user to investigate the relation between fuel consumption and the various sea states and directions that the ship may encounter during her voyage. Based on the results from the operational performance prediction model and real time climatological information, different options for the ship's navigation course can be evaluated according to a number of objectives, including: maximising safety and minimising fuel consumption and voyage time. By incorporating this into a decision support tool, the ship's crew are able to make an informed decision about what is the best course to navigate. In this study the Energy Efficiency of Operation (EEO) is defined as an indicator to illustrate the ratio of main engine fuel consumption per unit of transport work. Two case studies are carried out to perform the prediction of ship operational performance for Suezmax and Aframax Oil Tankers, and the results indicate that the semiempirical ship operational performance prediction model provides an extremely quick calculation with very reasonable accuracy, particularly considering the uncertainties related to the parameters of interest for the case study data. Within the case studies, the additional fuel consumption caused by the combined hull and propeller fouling and engine degradation is included in the model as a time-dependent correction factor. The factor may assist the ship owner/operator to determine the hull coating selection, and/or the dry-docking and main engine maintenance strategy
Economic pressures and regulatory requirements have brought about a great interest in improving ship propulsion efficiency. This can be exercised by installing Energy Saving Devices (ESD) such as Propeller Boss Cap Fins (PBCF). This paper demonstrates an approach for optimising PBCF by using Computational Fluid Dynamics (CFD) analysis. The conducted Reynolds-averaged Navier-Stokes (RANS) CFD open water model tests were validated by comparison with experimental data until the simulation was deemed satisfactory within the capabilities and limitations of the model. A design and optimisation procedure was defined to analyse the impact of ESDs on propeller efficiency and then used to evaluate the influence of alternative geometric parameters and locations of the PBCF on the hub. This analysis was done at full scale using high fidelity CFD-based RANS methods. Outcomes of the study include a design and optimisation process that can be used for the analysis of other ESDs on the market. The influences of various PBCF geometry were examined with optimal solutions presented for the analysis case. Results indicated a net energy efficiency improvement of 1.3% contributing to a substantial minimisation of cost and energy consumption. A reduction in the hub vortex was also clearly identified and presented
Energy efficiency improvements in the shipping industry are being driven by economics, compliance and customer requirements. Whilst various technological and operation improvements are known and available, with many being demonstrated to be cost effective and with savings reported in the industry, their take up in the world fleet remains low. This low take-up can be considered due to many different barriers, as explored in various research studies. However the aim of this paper is first to understand how these barriers are created by considering how ship operations function day-to-day within the context of mainstream business practice. A holistic view of operations is required and is presented in this paper, including consideration of business focus areas in parallel with the functions of technical, operational and commercial stakeholders. With this laid-out, gaps within existing operations are discussed in relation to areas for practical improvements. From here, non-prescriptive mechanisms to enable a desired future are proposed; including the integration of mandates, processes and systems. Case studies are given throughout the paper using hull and propeller maintenance as a recurring example of a typical decision making processes and best practices
The articles published by the Annals of Eugenics (1925–1954) have been made available online as an historical archive intended for scholarly use. The work of eugenicists was often pervaded by prejudice against racial, ethnic and disabled groups. The online publication of this material for scholarly research purposes is not an endorsement of those views nor a promotion of eugenics in any way.
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