determination of the reference speed at scantling draught and its influence on EEDI values. In the development of the correction factor only energy efficient vessels, with small improvement potential, and reliable reference speeds were included.
Proposal accepted by IMO Following the study the Dutch government proposed the inclusion of three correction factors in the EEDI calculation guidelines for general cargo ships smaller than 20,000 dwt. The proposal was accepted and a final version will be prepared for adoption during MEPC- 65 in May 2013.
EEDI reference line for general cargo ships
by the wide variety of these ship designs because of their varied operational profiles, types of cargo handled and sailing areas.
Solution for small general cargo ships In order to achieve a fairer inclusion of general cargo ships within the EEDI reg- ulatory framework, three correction factors have been developed by Conoship, a design office specialised in Short Sea Vessels, and MARIN to compensate vessels for differences in operational profile, additional class nota- tions and installed loading gear. MARIN used a subset of its speed/power database to determine which parameters have a significant effect on the required power. Although not all EEDI parameters (such as the deadweight) are included in this data- base, it does contain high quality speed- power measurements in a controlled environment in relation to the main dimen- sions of the ships. From a selection of around 90 ships within the deadweight range of the general cargo population, regression analysis found that the volumetric Froude number and block coefficient explained a large part of the variation in the EEDI values.
Following this, partners in the industry project group - consisting of shipowners, builders and designers - supplied detailed and comprehensive data from more than 70 general cargo vessels. The EEDI value was calculated for all these ships. MARIN per- formed a hydrodynamical benchmark on this database in order to qualify the power- ing performance of the ships. For each ship the reference speed in the EEDI condition
report 21
from the database was compared to a set of 10 automatically selected similar vessels from the MARIN database and then they were classed according to their ranking among the 10 ships. Three classes were used depending on the amount of hydrody- namical improvement potential and these were expressed as a percentage of the power at constant speed. Resulting analysis showed the importance of an accurate
Hull form optimisation and testing of the powering performance by means of a combination of CFD and model tests will also continue to play an important role under the EEDI regime, when the required index is reduced over time. Preliminary verification of the EEDI at design stage and final verification at sea trial requires a transparent model basin process.
This project was supported with funding from the Maritime Innovation Programme (MIP)
General Cargo vessels often carry a wide diversity of cargo. Here Wagenborg’s MV Asiaborg with a cargo of iron ingots, nickel concentrate in bulk, containers and casco’s of inland vessels as deck cargo, all at the same time.
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