Excessive acceleration criterion, developed by the International Maritime Organization within the Second Generation Intact Stability Criteria, deals with lateral accelerations experienced by people onboard. Level 2 criterion considers the ship at zero speed in beam waves, neglects diffraction and gives the expressions for the Froude-Krylov roll moment. In this paper, the Level 2 procedure is generalized for any ship speed and heading by developing the expressions for the Froude-Krylov exciting roll moment as a function of the heading angle and introducing a variance preserving transformation from encounter to wave frequency. The proposed procedure can be easily implemented in a user's code to assess the simplified Operational Guidance without the use of commercial software. The proposed expression is validated comparing the Froude-Krylov roll moment with the one obtained by the 3-D potential code HydroStar®, referring to a barge and a bulk carrier. The bulk carrier is selected as test case to develop the simplified Operational Guidance according to the proposed procedure. A polar diagram representation is chosen to identify safe combinations of ship speeds and heading while a tabular representation is proposed for a given heading to identify the minimum ship speed to avoid large lateral accelerations, for the sea states reported in standard wave scatter table.
Excessive acceleration simplified Operational Guidance / Begovic, Ermina; Boccadamo, Guido; Rinauro, Barbara; Rosano, Gennaro. - In: INTERNATIONAL JOURNAL OF NAVAL ARCHITECTURE AND OCEAN ENGINEERING. - ISSN 2092-6782. - 14:(2022), pp. 100473-100489. [10.1016/j.ijnaoe.2022.100473]
Excessive acceleration simplified Operational Guidance
Begovic, Ermina;Boccadamo, GuidoWriting – Review & Editing
;Rinauro, BarbaraSoftware
;Rosano, Gennaro
Methodology
2022
Abstract
Excessive acceleration criterion, developed by the International Maritime Organization within the Second Generation Intact Stability Criteria, deals with lateral accelerations experienced by people onboard. Level 2 criterion considers the ship at zero speed in beam waves, neglects diffraction and gives the expressions for the Froude-Krylov roll moment. In this paper, the Level 2 procedure is generalized for any ship speed and heading by developing the expressions for the Froude-Krylov exciting roll moment as a function of the heading angle and introducing a variance preserving transformation from encounter to wave frequency. The proposed procedure can be easily implemented in a user's code to assess the simplified Operational Guidance without the use of commercial software. The proposed expression is validated comparing the Froude-Krylov roll moment with the one obtained by the 3-D potential code HydroStar®, referring to a barge and a bulk carrier. The bulk carrier is selected as test case to develop the simplified Operational Guidance according to the proposed procedure. A polar diagram representation is chosen to identify safe combinations of ship speeds and heading while a tabular representation is proposed for a given heading to identify the minimum ship speed to avoid large lateral accelerations, for the sea states reported in standard wave scatter table.File | Dimensione | Formato | |
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