As IMCA informs a vessel collided with the working platform on a wind turbine Transition Piece. The incident happened during inclement weather conditions. When the vessel turned to independent joystick control, it was left without drive 120m from the Transition Piece.
A vessel collided with the working platform on a wind turbine Transition Piece. The incident took place during worsening weather conditions. The vessel was on DP, when it was decided to pull off. While moving away from the tower, it switched to independent joystick control. After that, the thrusters returned to zero pitch, leaving the vessel without drive, about 120m from the Transition Piece.
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The wind at that time was 28 knots. The weather and sea had already started to turn the vessel back towards the Transition Piece. The crewmembers attempted to regain control of the vessel using the joystick. They managed to regain control of the vessel but did not prevent two collisions.
The first happened between the Transition Piece external working platform and the upper bulkhead of the vessel, and the second between the vessel’s crane platform and the Transition Piece external working platform.
After the incident the vessel’s DP systems, joystick systems and manual control systems were tested. An additional failure mode and effects analysis (FMEA) test was carried out. All systems were found in good working order without any technical defects.
Probable cause
Following this incident, IMCA informed that the following played a direct role in the accident:
- Poor judgement of situation by the vessel Master;
- The vessel was already moving against an increasing wind and was still within the wind farm boundary;
- Insufficient awareness of DP system handover procedures and the adverse effects in the actual situation;
- The officer of the watch handover procedure was unclear to those involved;
- The decision to change over in a position in close proximity to the Transition Piece was inconsiderate;
- The Master misjudged how the systems would perform during the transition from DP to independent control.
Lessons learned
As a result of the accident, IMCA suggested the following as key consideration points, in order to prevent similar incidents:
- Full understanding on changeover procedures and relationship between (DP) systems;
- Full understanding of vessels DP systems and verification thereof (no DP system is the same despite naming);
- Bridge resource planning, especially transiting between work areas should be improved.
Namely, the ship operators, did the following as a response to the accident:
- Revision of DP operations manual to fully cover changeover procedures;
- Revision of DP familiarisation process to include better verification;
- Introduction of a recordable in field passage planning.
