To combat climate change, efforts to reduce greenhouse gas (GHG) emissions are being made in all industries. The shipping sector is also one of the industries that emits GHG, including carbon. One way to reduce GHG emissions in the shipping sector is to use shore power (SP) rather than auxiliary engines during berthing. Port authorities are actively expanding SP facilities because it is possible to achieve the long-term goals of environmental benefits and green ports. However, the low economic feasibility of SP is a stumbling block for ship operators. Therefore, in this study, an economic analysis of SP use was conducted by container-ship size from the perspective of ship operators in consideration of benefits from differences in fuel oil and electricity prices, benefits through carbon emission reduction, and incentives from the port authorities. The result of the analysis showed that the benefit from the price of oil as well as the converted benefit from carbon emission reduction increased according to the size of the vessels. The economic analysis of a single port confirmed that small ships providing feeder services presented economic feasibility due to low installation costs and increased number of calls, while insufficient economic feasibility was presented for large ships above the old Panamax class due to the increased costs for installation. However, economic feasibility differs widely depending on whether port incentives are provided, and it was estimated that even large ships will be able to secure the economic feasibility of using SP if additional calls are made to ports that provide similar policy advantages.

When analyzing ship accidents, there may be doubts whether appropriate countermeasures had been taken to prevent known types of accidents. This study aimed to suggest possible solutions by investigating the status and issues associated with the implementation of countermeasures using importance–performance analysis (IPA), Borich’s needs assessment, and locus for focus models based on previously identified causes of the ship accidents. As a result, firstly, we confirmed that there is a need to enhance education and training on specific knowledge, understanding, and proficiency (KUP) regarding ship stability, emergency response, and type specific training. Secondly, we confirmed that there is a need for a system of monitoring a seafarer’s KUP even while onboard a vessel—that is, after completion of identified training. Additionally, it is necessary to improve the seafarers’ working environment, which is subject to regulations. Thirdly, difficulties in solving wrong practice parts of safety and efficiency, such as the costs associated with implementation of safety regulations, were identified as the main reasons for the causes of the “not amended yet” sector after accidents. Lastly, the tools that were employed in this analysis can be used to confirm the implementation status of the actions to be taken after a ship accident.