In 2016, an accident in the United Kingdom in which people wearing lifejackets were found in face-down positions in water led to an investigation into the influence of clothing on the righting performance of lifejackets on board ships. The results showed that the righting performance is reduced when lifejackets are worn over clothing. In addition, the reproducibility of the righting test was poor when the subject was wearing clothing. Therefore, developing a highly reproducible righting test method for lifejackets considering the influence of clothing is required.

In this study, we present a reproducible righting test method for lifejackets using almost impermeable buoyancy material instead of clothing. The purpose of using buoyancy material is to simulate the observed effect where clothing diminishes the righting performance of the lifejacket. The size and arrangement of the buoyancy material in this study were determined using a numerical evaluation method for the righting performance of the lifejacket, considering the influence of clothing, as proposed by the authors. The accuracy and reproducibility of the proposed righting test method were confirmed by comparing the results of the lifejacket righting tests performed by human test subjects wearing clothing and buoyancy materials.

Many studies have been conducted on optimal ship routing to evaluate zero emissions for advancing marine transportation. At the same time, the persistent challenge of condensation within loaded containers remains unresolved. This study introduces a novel perspective by considering the minimization of condensation risk as a key factor in evaluating containerized transport conditions. To achieve this, we conducted onboard weather parameters measurements on a 20,000 TEU container ship to determine the spatiotemporal variations of air conditions and condensation probabilities during a voyage between Far East Asia and Europe. First, the accuracy of the measured results was compared with the European Center for Medium-Range Weather Forecasts Reanalysis v5 (ERA5) for each season and sea region. Second, the condensation probabilities were compared for each voyage. Results revealed that the error in ERA5 increased in narrow channels, and solar radiation exhibited some differences in each season and sea region. ERA5 overestimated the condensation probability by 9—28% compared with the measured results owing to the error in solar radiation. Thus, solar radiation is the key factor affecting the condensation inside containers.