202308 - Car carrier stability less than required
In the early morning hours, a car carrier departed port in a partially loaded condition. As the vessel progressed out to sea in a river channel, a 68° starboard turn in the channel was required. The pilot ordered 10° of starboard rudder.
As edited from NTSB (USA) report NTSB/MAR-21/03
There was no indication from anyone on the bridge that there were any concerns with the vessel, and no alarms sounded on the bridge. Shortly after, the pilot ordered 20° starboard rudder. Seconds later he ordered the rudder returned to midships. But within seconds, the vessel started to heel significantly to port. The pilot ordered the helmsman to move the rudder to port to counter the increasing heel but this action did not arrest the heel. The vessel reached a heel of 60° to port in less than a minute before grounding on the shallow area outside the channel.
Responders were initially able to rescue the pilot and 19 of the 23 crewmembers on board. Four engineering crewmembers remained trapped in the engine room until the following day when responders cut into the vessel’s hull to rescue them. Thankfully, no fatalities were incurred during this accident, and only two serious injuries were suffered. Monetary cost including the total loss of the vessel, cargo and salvage costs was estimated at more than 450 million USD.
The official investigation found, among other things that; The car carrier’s GM at the time of the heeling was not more than 1.8 metres, well below the 2.45 metre GM reportedly calculated in the stability computer. The investigation postulates that the chief officer had entered the data for the ballast tanks into the stability computer manually, and in doing so had made a data entry error. This in turn led to an incorrect determination of the vessel’s stability. At a higher level, the investigation found that the vessel operator did not have a method in place (training and auditing) to ensure that the chief officer, although experienced, was proficient in using the shipboard stability computer.
Lessons learned
When only one person is responsible for a safety-critical task without a backup to help identify possible errors, single point failure can occur. Had the Master taken a more active role in reviewing aspects of the vessel’s stability and the chief officer’s stability calculations, he may have been able to identify the error.
Given the critical nature of stability calculations on car carriers, it is of utmost importance that operators ensure officers are well trained in the use of the loading computers on board, and that they have adequate procedures in place to guide crew in ballasting practice and sequencing.
Editor’s note: Other ‘stability hiccups’ on car carriers can be found in MARS reports 202041 and 202043. Notably, an investigation into a similar accident involving a car carrier in 2016 uncovered evidence that suggests sailing without a finalised and accurately calculated GM is a practice that extends to the car carrier sector in general. Without proper training it is likely that unsafe practices will become the norm. When unsafe practices become the norm, it is only a matter of time before an accident re-occurs.