Empirical Analysis of the Relationship Between Ship Management System Quality and Port State Control Detention Rates for Nigerian-Flagged Vessels

Port state control detention rates serve as a measurable proxy for ship management system quality, and understanding this relationship carries implications for Nigerian maritime policy and flag state administration. This study empirically analyses the association between safety management system certification quality and port state control detention outcomes for Nigerian-flagged vessels inspected at regional ports between 2018 and 2023. Drawing on a mixed-methods research design, the study combines quantitative analysis of port state control deficiency and detention data obtained from the Paris, Tokyo, and Abuja Memorandums of Understanding with qualitative data from semi-structured interviews with twenty ship managers, five port state control officers, and three flag state administration officials. A logistic regression model was developed to identify predictors of detention, controlling for vessel age, type, and gross tonnage. Findings demonstrate a statistically significant inverse relationship between ISM Code audit frequency and detention probability, suggesting that companies with more active internal auditing programmes achieve better port state control outcomes. Vessel age remains a significant predictor, but its effect is substantially moderated by management system quality. The study contributes an empirical model to the literature that is specific to the Nigerian flag context and fills a notable gap in regional maritime safety research. Recommendations for the flag administration include mandating a minimum internal audit frequency and introducing a vessel risk profiling system that targets inspection resources on low-audit, older vessels. Keywords: port state control, ISM Code, Nigerian flag, detention rate, ship management