The UK MAIB in the first case of its latest edition of the Safety Digest provided a sobering example of the power that can be generated when gale force winds oppose strong tidal streams; a small laden cargo vessel was overwhelmed and capsized when the ship entered an extremely hazardous channel at the very worst time possible. Sadly, none of the ship’s crew survived.
The incident
A small, laden cement carrier capsized while on passage through a coastal channel that was notorious for its powerful tidal races and associated extreme sea conditions. As the vessel approached the channel, the weather deteriorated and gale force winds were opposing the strong tidal stream; this was creating treacherous conditions that were dangerous for small vessels.
On entering the channel, it is evident from AIS evidence that the bridge team slowed the vessel down, almost certainly to reduce the risk of pounding or ploughing as they headed into the dreadful sea conditions. Due to the direction of the tidal stream, it is also evident that course alterations were required to maintain a safe navigational track over the ground. However, these course changes had the effect of placing the large sea increasingly on the vessel’s beam.
When close to the area of worst sea conditions, the vessel capsized and remained afloat upside down for a considerable period of time; none of the crew survived. The alarm was not raised until about 25 hours later when the upturned hull was spotted by a passing ferry. The accident had gone unnoticed because: the capsize was so rapid that there was insufficient time for the crew to call a “Mayday”, the EPIRB almost certainly became trapped and did not float free, and the AIS transmissions ceasing was not observed ashore.
The hazards presented by the tidal races were well publicised and the channel was impassable to small vessels during certain tidal conditions. The ship and its master had passed through the channel many times before and the master had previously taken action, normally by altering course, to avoid entering the channel at the dangerous times. About 3 months prior to the accident, the master had altered course across the sea in the approaches to the channel in order to avoid the extreme tidal races; however, this caused the vessel’s cement cargo to shift and resulted in a dangerous stability situation.
Lessons Learned
1. Passage planning is critical for every voyage; it needs to take into account all potential hazards and should include abort plans where necessary. In this case the ship entered the extremely hazardous channel at the very worst time of maximum opposing wind and current, creating the fatal sea conditions. Options were available to seek shelter or avoid the area.
However, the decision to press ahead with the voyage resulted from poor passage planning, a likely under-estimation of the environmental conditions, overconfidence in the vessel’s sea-keeping capability and an unwillingness to alter across the sea after the recent experience of a dangerous cargo shift.
2. Other factors were likely to have played a part in the decision making on board. The master and chief officer were in a 6-on / 6-off routine at sea and both also had duties to fulfil in harbour. Such a routine can be exhausting in the short sea-trading routes that the vessel was undertaking; this situation can be made worse by poor weather and constant ship movement, disrupting crew rest.
3. Safety at sea must always be a priority ahead of commercial pressures. The crew had experienced some difficulties loading the vessel and this had caused a delay in departure. The delay in sailing might have created additional pressure on the crew to press ahead with the voyage in an attempt to regain the lost time.
4. It is important to understand your vessel’s stability condition and, for bulk carriers, the cargo bulk density value is critical. The vessel’s stability condition was not accurately determined after the accident; however, it was established that the assumed bulk density value for the cargo was greater than reality, which could potentially have generated a false impression of stability.
This created a situation where the vessel was potentially more vulnerable to capsize than the stability calculations would have indicated
Source & Image credit: UK MAIB
