Dynamic Effects of Port State Control on Ship Risk Profiles

Port state control (PSC) is crucial for vessel safety and environmental standards, especially under the International Maritime Organization’s New Inspection Regime. Despite the necessity of PSC inspections, multiple inspections by memoranda of understanding (MoUs) raise concerns about resource allocation and inspection efficiency. This study examines PSC dynamics and their impact on ship risk profiles (SRPs) using data from 191,667 inspections of 30,386 vessels under the Tokyo MoU between 2017 and 2023, aiming to evaluate the effectiveness of repeated inspections in mitigating maritime risks. A dynamic Bayesian network framework is developed with two models: a rolled model to capture the dynamic evolution of inspection outcomes and an unrolled model to reveal structural dependencies among inspection, ship characteristics, and risk outcomes. The findings show that 83.16% of ships were inspected at least twice, and 54.22% were inspected more than five times. Sensitivity and influence analysis reveal that SRPs from the fourth and fifth inspections exert the strongest influence on current SRP classification, highlighting the compounding effect of prior inspections. These results confirm that iterative inspections not only refine ship risk profiles but also significantly enhance the predictability and management of maritime safety risks, reinforcing the strategic importance of sustained PSC monitoring.