Sea Technology

MAR 2018

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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Page 12 of 45 March 2018 | ST 11 Data inputs include the hull, the propellers, the rudders, the general arrangement and the main engines to calcu- late fuel consumption and motions on board the vessel during simulated voyages. Voyages are from port to port, start on a given day at a given time and have a target ar- rival date and time and an initial routing. Realistic conditions are created by using hind-cast en- vironmental data of the wind, waves and currents on the actual route the vessel will follow and using simulations of how the vessel will be operated. That includes deci- sions on the engines that minimize fuel consumption and what route to follow to avoid bad weather. It is easier and more accurate to assess the impact of design changes on fuel consumption and comfort using a single, consistent approach based on the same model and realistic weather conditions and a realistic route than to deal with these issues separately. Considered separately, each type of environmental data has inaccuracies, and there is a risk of inconsistency between analyses and communication failures between different design disciplines. Foreship's initiative relies on es- tablished ship design and construc- tion software, but introducing op- erating data such as voyage route planning at an earlier stage than is customary. Even though we are us- ing well-known software in this application, we are not aware of others doing this sort of study at any stage using any system. There are organizations with voyage simulation software that don't design ships, and there are designers who don't in- clude operational simula- tions. It is also the case that some software packages in use are lim- ited, and simply cannot consider weather routing. Process The effects of design decisions on fuel consumption and comfort on board can be evaluated quick- ly and realistically to give the most accurate picture possible of how the ship will perform before it actually goes into service. From hind-cast data we get the wind, current and wave conditions during the voyage. These are used in the fuel consumption and motion calcula- tions. The engine operating mode and the route the ves- sel follows are optimized for minimum fuel consumption and minimum motions, which would reflect the deci- sions made by the crew on board the vessel to save fuel and keep the vessel safe. With many years of data we can simulate voyages simply by changing the departure date. Using this approach, the full impact of a design change can be considered in a single analysis. If the wid- ening of the hull were being considered, for example, the effects on fuel consumption, speed, engine profile and passenger comfort could be simulated, and the different possibilities for engine configurations investigated very quickly. We could assess any change in the design—for example, the size of fin stabilizers and bilge keels from both the fuel consumption and comfort perspective—but also how best to operate the vessel and how this would change with changes in the vessel design. The bar graphs show typical results comparing vessel performance on different itineraries and the speed pro- file of the vessel.

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