Since industrialization, steam-powered ships were introduced, expanding the sphere of human activities globally. The propulsion system on a vessel plays the most crucial role, and the current marine propulsion system is generated from the main engine.
According to 「2020 Statistics of Marine Accidents」, the proportion of engine accidents in cargo ships, oil tankers, and tugboats were relatively high. During the period 2016-2020, a total of 1,495 marine accidents occurred on general cargo ships, oil tankers, and tugboats, of which 162 were engine accidents, accounting for a high proportion of 10.8%. Although the engine failure is only one of various maritime accidents, including collision and fire, it is considered a serious problem as it involves a risk of causing enormous personal and property damage. Suppose the main engine fails under an extreme sea state and loses the propulsion power. Prompt action is required since the vessel may lose stability due to waves and winds or sink due to flooding. However, there is a limit to the ship's ability to repair and restore the engine on its own due to a lack of resources, spare parts, and repair equipment on site. Therefore, it is important to identify hazards and reduce the risk to prevent engine-related accidents during navigation.
This study aims to identify hazards and suggest plans to improve by analyzing main engine failure cases that can cause considerable human and property damage during the navigation of both domestic and foreign cargo ships. We first identified the maritime laws related to maritime accidents and analyzed the Korea Maritime Safety Tribunal. In addition, we identified areas necessary for theoretical application in this study through the analysis of the literature of previous studies. We then collected the Marine Accident investigation reports from January 1st, 1988, to December 31st, 2020. This study identified 70 main engine failure accident cases among the collected reports to identify the occurrence frequency and damage strength (total loss/ partial loss/ minor loss/ undamaged) based on the main engine types.
Additionally, while recognizing that the risk factors of coastal and ocean-going vessels may vary depending on external factors, such as the operating environment of the main engine and the level of ground support, this paper aims to test the hypothesis on whether the different navigation areas cause the difference in the occurrence frequency. The hypothesis was tested by applying the chi-square test analysis method to confirm the correlation of categorical variables. The test confirmed that the p-value for the difference in the frequency of main engine system failure of groups with different navigation areas fell below the set ɑ value of 0.05 (5%). This paper rejects the null hypothesis that there is no difference in the occurrence frequency between different types of the main engine of coastal and ocean-going vessels. Instead, the alternative hypothesis that there is a difference between different groups is adopted.
According to the adopted alternative hypothesis, the main engine failure of cargo ships was classified into coastal and ocean-going cargo ships, and risk assessment was conducted for each group. The risk factors, such as damage strength and occurrence frequency, were quantified and addition using the set formula was used to estimate the degree of risk. Through this numerical approach, this paper attempts to derive the high-risk hazard that requires prioritization to reduce risks by scoring and grading the risk levels for each main engine system of coastal and ocean-going cargo ships.
Based on the hazard class matrix set by the researchers, the risk level according to hazard for each main engine system was divided into levels I, II and III. In the case of coastal cargo ships, three among 13 main engine system-hazard factor combinations were classified as risk level II or higher (≥6 points). On the other hand, in the case of ocean-going cargo ships, four out of ten main engine system-hazard factor combinations were classified as risk level II or higher (≥6 points). This paper suggests engineering and administrative measures to reduce high-risk hazards by main engine system of the seven identified cases of risk level II or higher (≥6 points).
The researchers hope that the findings of this paper on high-risk hazards for each main engine system of coastal and ocean-going cargo ships and the measures presented to reduce the risks can contribute to the policy decisions of the government to prevent maritime accidents and the establishment of voluntary safety measure of shipping companies.