The International Maritime Organization (IMO) developed new regulations on energy efficiency for new ships, called the Energy Efficiency Design Index (EEDI), which entered in force on 1 January 2013 for main ship types. During the development of this new IMO regulation, some flag state administrations as well as ship owners' associations underlined the need to provide sufficient power to ensure safe manoeuvring in adverse conditions. The concerns of the maritime community regarding possibly underpowered vessels have prompted the International Association of Classification Societies (IACS) to develop a guideline to evaluate whether a ship has sufficient power to safely manoeuvre in adverse conditions. Due to the complexity of the task, IMO implemented - as interim measure - only requirements for oil tankers and bulk carriers. The paper documents that this interim measure is in conflict with the EEDI regulations for smaller ships. Noting the current discussion on the definition of adverse conditions, the paper presents an application of the simplified assessment, following IMO Interim Guidelines and taking into account the ship and propulsion systems particulars to predict forward speed in head waves. The paper also presents the application of a tool to perform the comprehensive assessment and compares the results with the other assessment levels. The Energy Efficiency Design Index will have a considerable influence on future ship designs. The strict requirements for up to 30% less specific CO2 emissions for ships built from 2025 may have unexpected side-effects, however. With the progressively increasing reduction in propulsion power, safe manoeuvring in adverse weather conditions will possibly be jeopardized in future. Here, the demands of environmental protection will collide with the demands of safety. This conflict is already evident in the current IMO guidelines. The examples given in this paper Indicate that the definition of "adverse conditions" will play a decisive role in determining the manoeuvrability. The significant wave heights initially Introduced into the discussion by the industry would most probably make most of the existing ships appear to be unsafe. On the other hand, the values now fixed are only applicable for a maximum HS = 5,5 m, and are thus possibly not strict enough to ensure the future manoeuvrability of ships in actual practice. This results in the following recommendations for further studies or developments: Documentation of waves and wind near the coast; Evaluation of reports on critical manoeuvring situations; Further validation of numerical methods for forecasting the drift forces, including the added; resistance in waves for small ship speeds Systematic calculation of various ship types and sizes. The above-mentioned developments are (to some extent) being carried out in newly initiated R&D projects with public funding; PerSee and SHOPERA. In both cases, consortia have formed to advance the development of numerical methods and their validation for forecasting the manoeuvrability of ships in realistic sea states.
Energy efficiency design index vs. safe manoeuvring in adverse conditions
2014
11 Seiten, Bilder, Tabellen, 19 Quellen
Conference paper
English
Drive and manoeuvring units: How safe is safe enough?
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Drive and manoeuvring units: How safe is safe enough?
Online Contents | 1998
Online Contents | 1998
Online Contents | 1995
Engineering Index Backfile | 1935
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