Which class of DP vessels is required to have both thruster and power redundancy?

Class 2 DP vessels are required to have both thruster and power redundancy to enhance safety and operational resilience. The rationale behind this requirement stems from the operational scenarios in which Class 2 vessels are typically utilized, such as offshore construction, diving support, and other applications where the vessel's position must be maintained with high accuracy and reliability.

In Class 2 systems, the regulations stipulate that the loss of a single thruster or power source should not result in the vessel losing the ability to maintain its position. This redundancy ensures that should any single failure occur, there are backup systems in place to prevent a loss of dynamic positioning capability, thus minimizing risk to both the vessel and the operations being conducted.

Other classes, such as Class 1, do not require the same level of redundancy and can operate with less backup since they are not typically engaged in the same high-risk or complex operations. Class 3 vessels have even stricter requirements as they must maintain their position even in the event of a complete power failure, leading to a different set of operational criteria. By understanding the specific requirements tied to each class, one can appreciate why Class 2 emphasizes both thruster and power redundancy.