Push / force off

The event in focus is a push-off incident, where the vessel collided with the platform during a pause in operations.

The incident occurred while the vessel was engaged in the transfer of cargo. During this process, the vessel was operating under fully automatic Dynamic Positioning (DP) Mode. Given the smooth progress of operations, the vessel was instructed to maintain a standby position for approximately one hour, positioned marginally upwind of the platform.

The Dynamic Positioning Operator (DPO) made the decision to deselect the automatic Surge function on the DP system, opting instead to manually control the surge axis using a joystick. 

This decision became critical as weather conditions began to deteriorate progressively. In response to the changing weather, the DPO manoeuvered the vessel’s bow into the wind and waves to maintain position effectively.

However, when the vessel was approximately 20 metres from the platform, it encountered a sudden and significant escalation in environmental forces. The rapid onset of these conditions exceeded the DPO’s capacity to react promptly, resulting in the vessel being pushed into the platform, culminating in a collision.

In retrospect, given the knowledge of a minimum one-hour standby period, it would have been more judicious for the vessel to reposition to a safer blowoff position. This strategic relocation could have potentially mitigated the risks associated with environmental forces.

A critical aspect for analysis is the decision to deactivate the automatic surge functionality of the DP system. This action necessitated manual intervention by the DPO to apply appropriate forward thrust via the joystick, counteracting environmental forces acting on the vessel. The reliance on manual control in dynamically changing weather conditions presents a significant risk factor that warrants further examination.

The lessons learned from this incident emphasise the importance of anticipatory positioning in response to known operational pauses, especially in environments prone to rapid weather changes. Additionally, the reliance on manual controls over automated systems in critical situations should be carefully evaluated to ensure optimal response capabilities under adverse conditions.

By deselecting the surge, the vessel cannot be qualified as being on DP but under manual control, which means that the Operator needs to be in attendance at all times.

Gain of the Joystick will have to be adjusted as per weather condition.

Stand by rules, which exist with most of the charterer need to be fully understood by the DPO and reflected in Master DP standing orders. Vessels needs to be set up as per charter rules, in particular within the 500m zone.