The Transportation Safety Board of Canada released its investigation report into the collision of the dredger FRPD 309 with the loaded barge Evco 60, on 5 December 2017, in the Fraser River.
The incident
On 04 December 2017, the dredger FRPD 309 departed a shipyard in Delta, BC, to begin dredging in the Fraser River. The vessel is a conventional trailing arm suction dredger, with the bridge and accommodation located forward and machinery space located aft. Before departure, the crew had carried out pre-departure checks, a safety meeting, and emergency drills.
After arriving at the dredging location, the vessel started dredging sand and sediment from the river bed into the hopper using the 2 trailing arms and a dredging pump. When the hopper was filled, the sand and sediment was pumped ashore via a pipeline. The master left the bridge, handing over the command of the vessel to the officer of the watch (OOW). Two engineers, 2 deckhands, and a pipe operator were also on duty.
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As the vessel was turning and the pipe operator was raising the trailing arms to the deck level, the vessel experienced a blackout. Approximately 2 to 5 seconds elapsed before the power management system restored electrical power to the vessel. Because the power management system was in semi-automatic mode, the second engineer started the third generator and brought it online so that load could be increased to operational levels. Once power returned, the bridge team reset the electronic equipment that had tripped as a result of the blackout.
2 minutes after the blackout, the OOW resumed the turn to port and the vessel continued towards the discharge pipeline location. However, at this time, the 2 engineers in the engine room were still resetting numerous alarms and both essential and non-essential circuit breakers, including some located in the fore part of the vessel, and they did not have enough time to restore the vessel to normal status before it continued the voyage. During this time, the bridge team contacted the engine room to request resetting the shaft generators, hydraulic pumps, and the winches.
During the blackout, the control air compressor and service air compressor had tripped and had to be reset locally.
The control air receiver, which supplies compressed air to keep the main engine clutches engaged, is maintained at 7.5 bar. The system is fitted with 2 alarms. However, they went unnoticed by the engineers, who continued to be occupied with resetting tripped breakers and alarms.
As the vessel was proceeding to the discharge pipeline location, it lost propulsion. The main engine clutches had automatically become disengaged after the control air pressure fell below 5 bar. The loss of propulsion alarm activated on the bridge and in the engine room. As well, on the bridge, the indicators for the shaft generators and the propeller pitch went to zero. One of the thrusters, which was powered by the shaft generators, also became unavailable. The OOW attempted to clutch in the propulsion, but there was no response. A little later, the OOW called the master and informed him that the vessel had lost propulsion.
Meanwhile, the FRPD 309 continued proceeding ahead under its own momentum and was now on a collision course with the tug Storm Wave, which was towing the loaded barge Evco 60. The OOW on the FRPD 309 applied the rudder to starboard to steer the dredger away from the tug and tow.
The OOW notified the Storm Wave that the FRPD 309 had lost propulsion and requested that the tug keep out of the way. The general alarm was also sounded, and the deckhand on the bridge was instructed to go forward and let go the anchor.
Moments later, the OOW made an announcement on the PA system warning the crew of the imminent collision. Because the main engines were still running, the engineers did not know about the propulsion failure until the general alarm was sounded and the OOW made the announcement. One of the engineers had restarted both air compressors, but this was done too late to avoid the main engine clutches from disengaging. The dredger collided with the Evco 60 while making way at approximately 4.5 knots.
The investigation could not determine the cause of the blackout.
Damage
The FRPD 309 sustained damage to the shell plating and forepeak tank forward of the collision bulkhead. In addition, the port anchor was disconnected from its housing and became wedged in the Evco 60’s hull. The Evco 60 also sustained structural damage due to the impact of the collision (Figure 4).
Safety actions
After the collision, the company took the following measures:
- Revised the safety management system documentation related to emergency checklists and loss of propulsion;
- Revised familiarization and training and briefed the crew on these changes;
- Implemented training for all deck and engine room crew concerning safe parameters for air clutches and air telegraph;
- Conducted emergency drills related to failure and maintenance of the control air systems;
- Fitted a control air compressor with auto-start capability;
- The company is working on enhancing its training as well as developing a competency evaluation program.
Recommendations
According to the Transportation Safety Board of Canada, in this case, once power was restored to the bridge following the blackout, the vessel resumed manoeuvring towards the discharge pipeline location almost immediately, without allowing the engine room crew time to reset all the alarms and breakers and verify the operational status of the vessel’s systems and equipment.
The bridge team did not confirm with the engine room that they had completed restoring the vessel’s systems, nor did the engine room communicate to the bridge team that more time was needed to do so.
This incident shows the importance of taking the time to make sure a vessel is fully restored to operational status following a blackout. Using comprehensive blackout recovery checklists and carrying out meaningful drills are tools that can help make a crew’s response to a blackout more effective.
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