Intact stability of feeder container vessels – Loss-of-stability incidents during cargo operations
Lignell, Antti (2025)
2025
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-2025112429495
https://urn.fi/URN:NBN:fi:amk-2025112429495
Tiivistelmä
Feeder container vessels have recently experienced multiple stability loss events during their cargo operations that have resulted in capsizing the ship. The motivation of this thesis is to perform qualitative and quantitative study to learn what the underlying reasons for these incidents are. The qualitative part is based on the literature analysis of past incidents, and the quantitative part consists of computer simulations of the factors that may lead to loss of stability.
A representative model vessel (907 TEU container feeder) was chosen and various stability threatening cases were modeled by loading computer software of that vessel during simulated cargo operations. The static stability of the vessel was assessed by observing its change of metacentric height (deltaGM) during these perturbations. Different scenarios of loading errors, incorrect container weights and positions, wrong water densities, mistakes during ballast water operations, incorrect bunkering, and effect of deck icing were evaluated.
It was evident that the most prominent factor leading to capsizing this vessel type during cargo operations is a major mistake with water ballast operations. This is solely capable of turning the ship’s stability negative. Serious incorrect loading with wrong container positions and weights can also lead to serious outcome, as is evident with the previously capsized Mv Deneb incident. Delayed bunkering and other studied perturbations are able to turn vessel into negative stability, but only with synergistic fashion.
Human factors, especially poor communication, and incompetence were found to be the evident leading cause for these types of incidents. We also discussed that these incidents typically arise from multiple levels of simultaneous failures.
Current IS Code minimum metacentric height of 0.15 meters was challenged for this vessel type, since even rather minor simulated perturbations were able to turn the model vessel into state of unstable stability with this value. The practical ways how an officer of the watch can detect these situations is discussed together with suggested protocol how they should react when the ship is in danger of capsizing.
A representative model vessel (907 TEU container feeder) was chosen and various stability threatening cases were modeled by loading computer software of that vessel during simulated cargo operations. The static stability of the vessel was assessed by observing its change of metacentric height (deltaGM) during these perturbations. Different scenarios of loading errors, incorrect container weights and positions, wrong water densities, mistakes during ballast water operations, incorrect bunkering, and effect of deck icing were evaluated.
It was evident that the most prominent factor leading to capsizing this vessel type during cargo operations is a major mistake with water ballast operations. This is solely capable of turning the ship’s stability negative. Serious incorrect loading with wrong container positions and weights can also lead to serious outcome, as is evident with the previously capsized Mv Deneb incident. Delayed bunkering and other studied perturbations are able to turn vessel into negative stability, but only with synergistic fashion.
Human factors, especially poor communication, and incompetence were found to be the evident leading cause for these types of incidents. We also discussed that these incidents typically arise from multiple levels of simultaneous failures.
Current IS Code minimum metacentric height of 0.15 meters was challenged for this vessel type, since even rather minor simulated perturbations were able to turn the model vessel into state of unstable stability with this value. The practical ways how an officer of the watch can detect these situations is discussed together with suggested protocol how they should react when the ship is in danger of capsizing.