Manoeuvrability in adverse conditions: Case studies

Abstract

Introduction of the Energy Efficiency Design Index (EEDI) raised concerns that ship designers may simply reduce the installed power to satisfy EEDI requirements. To address the problem by in-depth research, EU-funded project SHOPERA (Energy Efficient Safe SHip OPERAtion) developed criteria and acceptance standards for the assessment of sufficiency of propulsion and steering systems of ships for manoeuvrability in adverse conditions. Here, their impact on ships of all types in the EEDI framework is investigated and compared with the statistics of relevant accidents collected in SHOPERA. The comparison shows that the proposed standards seem appropriate for tankers, RoRo cargo vessels, pure car carriers and gas carriers, whereas for small bulk carriers and small general cargo vessels, stricter standards may be needed if the same safety level is targeted for small ships as for large ones. The results also show that ships of almost all types studied can satisfy the proposed standards together with the EEDI phase 3 requirements, excepting bulk carriers and tankers, which can satisfy the proposed standards and EEDI phase 2 requirements but not those of phase 3. For RoRo passenger ships, satisfying the EEDI phase 3 requirements alone may be problematic because of other limitations concerning design and operation.