helps reduce fuel consumption and emissions


Efforts to reduce emissions continue worldwide. The maritime industry too, is pressing on with initiatives to cut back emissions. Undoubtedly,


reducing the basic ship powering need and hence, fuel consumption is one very effective way to reach this goal. A number of design issues that can achieve fuel savings for new or for existing vessels are explored here.


T


he set of related services ranges from fairly standard, basic design practice in modern ship design to more ad-


vanced, developing techniques, either aiming at specific details, novel propulsion applica- tions or an integrated approach leading to effective energy management. The latter approach in particular, requires early client involvement in the hydro-design in order to take into account operational issues right from the start of the concept design. In the end it ensures a design fit that is in line with the new requirements of the upcoming IMO definitions1


concerning the design and operations energy indices.


Early design involvement Basic ship design features a number of steps, which if properly applied, can already contribute to reduced energy demand in the early design stage. - The exchange of the so-called ‘hard’ design points, (maximum length, block coefficient, position of gearboxes etc.), for a design looking to minimise resistance will enhance the ‘green’ character of designs. Often early involvement in the design process enables this optimisation, without giving in too much to pure commercial requirements


Rob Grin,


Tom van Terwisga & Christian Veldhuis r.grin@marin.nl


10 report


- Designing for service facilitates an inte- grated approach towards energy manage- ment on board and hence, lower emissions. This approach requires knowledge of the


expected operational profiles of the vessel and of the available management options


- Designing for different operational condi- tions like speed and draught, often in combination with trim, can lead to lower fuel consumption. Again, the operational profile in terms of expected speed, draught and trim conditions are of key importance


Various hydro-design products can help achieve optimal designs and operational conditions. Some of these products are well- known steps in a hydrodynamic design and are facilitated by CFD tools and a final model testing confirmation. Others are the results of voyage simulation tools and new devel- opments in propulsion, or the integration of knowledge of various energy systems.


Hull design Reduction of the wave and frictional resistance are still the main aspects when it comes to hull design. To minimise wave drag, special attention has to be paid to the design of the bulbous bow, as well as to the fore and aftbody shape. The design of the bulbous bow should lead to optimum interference between the wave pattern of the bulbous bow and the forebody. In the past, the bulbous bow was mainly optimised for the trial speed and design draught but few ships actually sail in this condition. To have an overall improvement, the operational profile of the ship has to be taken into ac-


Integrated design approach


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