For DP Class 2 and 3 operations, why should at least three Position Reference Systems not be based on the same principle?

In dynamic positioning (DP) operations, particularly for Class 2 and Class 3 systems, it is essential to minimize the risk of a common mode failure. This concept refers to a situation where multiple systems or components fail simultaneously due to a shared vulnerability or dependency, which can lead to a significant compromise in safety and accuracy.

By ensuring that at least three position reference systems are not based on the same principle, operators can maintain greater reliability and redundancy. For instance, if all reference systems were reliant on similar technology or methodologies, a single failure could impact all systems simultaneously, resulting in a complete loss of positioning capability. By diversifying the principles behind the reference systems—such as using a combination of GPS, radar, and acoustic positioning—each system can function independently, thus reducing the overall risk in the event of an issue with one technology.

This approach helps to assure continuous operational integrity and strengthens the safety margins required for DP Class 2 and 3 operations, which are expected to handle more demanding scenarios and protect against potential failures. Consequently, this strategy is foundational in safeguarding against disruptions that could endanger the vessel and its operations.