What does the detention ratio calculate?

The detention ratio is a specific metric used in maritime safety and compliance assessments, particularly in the context of Port State Control. It is calculated by taking the number of detentions and dividing it by the number of vessel arrivals at a port. This ratio is essential because it provides insight into the prevalence of non-compliance issues among vessels, as well as the effectiveness of port authorities and inspectors in identifying and addressing safety concerns.

When the detention ratio is high, it indicates that a significant portion of vessels arriving at a port are found to be in violation of regulations, making the port a focus area for improvements in compliance. On the other hand, a low ratio may suggest better compliance levels among vessels and effective inspections.

The other options do not accurately reflect the definition or purpose of the detention ratio. For example, measuring the number of inspections against total vessels or defects does not directly relate to how many vessels are detained for non-compliance. Understanding the detention ratio helps in evaluating maritime safety standards and the overall effectiveness of inspection regimes.